Hi Michael,
Yes, something along those lines. Although I'd probably have the public
constructor take a `boolean` and have a private constructor for the
`Boolean` (this way, we can retire the config at some point without
affecting the API exposed by the class). Also, I would just hardcode it in
`send` instead of using an interceptor.
It would be interesting to get some thoughts on whether people think this
is OK given the constraints.
A note: message format version bumps are relatively disruptive for users
(and they impose a non-trivial maintenance cost). So, as Jun said, it would
be good to avoid bumping it many times in rapid succession. The last bump
happened in 0.10.0.0, which was released in May 2016. My personal
preference would be to wait until the May 2017 release for the next message
format bump.
We have a number of KIPs currently being discussed that require a message
format bump: KIP-82, KIP-87, KIP-98 and KIP-101. Given that a lot of people
are going to be on holiday soon and taking into account the complexity of
the mentioned KIPs, it seems that we could, at best, get one of them in for
the January release. And it seems suboptimal to bump the message format
version for just one KIP when we know we have three others lined up. I hope
that explains my reasoning. Does it make sense at all?
Ismael
On Fri, Dec 16, 2016 at 1:53 PM, Michael Pearce <michael.pea...@ig.com>
wrote:
> Hi Ismael
>
>
> So I understand what is being suggested, is we allow on the ProducerRecord
> at time of construction to be nullable aka big B, Boolean, where old
> constructors set it to null.
>
>
> /**
> * Creates a record with a specified timestamp to be sent to a
> specified topic and partition
> *
> * @param topic The topic the record will be appended to
> * @param partition The partition to which the record should be sent
> * @param tombstone if the record is a tombstone marker.
> * @param timestamp The timestamp of the record
> * @param key The key that will be included in the record
> * @param value The record contents
> */
> public ProducerRecord(String topic, Integer partition, Boolean
> tombstone, Long timestamp, K key, V value) {
> if (topic == null)
> throw new IllegalArgumentException("Topic cannot be null");
> if (timestamp != null && timestamp < 0)
> throw new IllegalArgumentException("Invalid timestamp " +
> timestamp);
> this.topic = topic;
> this.partition = partition;
> this.tombstone = tombstone;
> this.key = key;
> this.value = value;
> this.timestamp = timestamp;
> }
>
> public ProducerRecord(String topic, Integer partition, Long timestamp,
> K key, V value)
> {
> this(topic, partition, null, timestamp, key, value);
> }
>
>
> Then within the KafkaProducer an enforced/defaulter interceptor or simply
> hardcoded in the on send if it detects the tombstone is null, it sets the
> tombstone to true or false based on a configuration property of the
> KafkaProducer?
>
> Aka in this method, or by adding a default interceptor ->
>
> @Override
> public Future<RecordMetadata> send(ProducerRecord<K, V> record,
> Callback callback) {
> // intercept the record, which can be potentially modified; this
> method does not throw exceptions
> ProducerRecord<K, V> interceptedRecord = this.interceptors == null
> ? record : this.interceptors.onSend(record);
> return doSend(interceptedRecord, callback);
> }
>
> e.g sample default interceptor method we can either just add this to the
> interceptors by default or code this same logic in the send/doSend logic.
>
> public class TombstoneInterceptor implements ProducerInterceptor
> {
> boolean defaultNullValueTombstoneMarker;
>
> @Override
> public void configure(Map<String, ?> configs)
> {
> defaultNullValueTombstoneMarker = (Boolean)configs.get("
> tombstone.default.null.value");
> }
>
> @Override
> public ProducerRecord onSend(ProducerRecord record)
> {
> if (record.tombstone() == null){
> boolean tombstone = false;
> if (record.value() == null){
> tombstone = defaultNullValueTombstoneMarker;
> }
> return new ProducerRecord(record.topic(), record.partition(),
> tombstone, record.timestamp(), record.key(), record.value());
> }
> return record;
> }
>
> @Override
> public void onAcknowledgement(RecordMetadata metadata, Exception
> exception)
> {
>
> }
>
> @Override
> public void close()
> {
>
> }
> }
>
> Is this a correct understanding?
>
> Cheers
> Mike
>
> On 16/12/2016, 21:16, "isma...@gmail.com on behalf of Ismael Juma" <
> isma...@gmail.com on behalf of ism...@juma.me.uk> wrote:
>
> Hi Michael,
>
> I am not sure about using a new policy. One other option (suggested by
> Gwen) is that the behaviour of the producer with regards to tombstones
> when
> you pass a `null` value and don't use the constructor that takes a
> tombstone can be influenced by a producer config. Not ideal, but would
> limit the complexity of maintaining compatibility while providing a
> path
> for the (what I think) are the right semantics.
>
> Ismael
>
> On Tue, Dec 13, 2016 at 8:32 AM, Michael Pearce <michael.pea...@ig.com
> >
> wrote:
>
> > Hi Ismael
> >
> > Did you see our email this morning, what's your thoughts on this
> approach
> > to instead we simply have a brand new policy?
> >
> > Cheers
> > Mike
> >
> >
> > Sent using OWA for iPhone
> > ________________________________________
> > From: isma...@gmail.com <isma...@gmail.com> on behalf of Ismael
> Juma <
> > ism...@juma.me.uk>
> > Sent: Tuesday, December 13, 2016 11:30:05 AM
> > To: dev@kafka.apache.org
> > Subject: Re: [VOTE] KIP-87 - Add Compaction Tombstone Flag
> >
> > Yes, this is actually tricky to do in a way where we both have the
> desired
> > semantics and maintain compatibility. When someone creates a
> > `ProducerRecord` with a `null` value today, the producer doesn't
> know if
> > it's meant to be a tombstone or not. For V3 messages, it's easy when
> the
> > constructor that takes a tombstone is used. However, if any other
> > constructor is used, it's not clear. A couple of options I can think
> of,
> > none of them particularly nice:
> >
> > 1. Have a third state where tombstone = unknown and the broker would
> set
> > the tombstone bit if the value was null and the topic was compacted.
> People
> > that wanted to pass a non-null value for the tombstone would have to
> use
> > the constructor that takes a tombstone. The drawbacks: third state
> for
> > tombstone in message format, message conversion at the broker for a
> common
> > case.
> >
> > 2. Extend MetadataResponse to optionally include topic configs,
> which would
> > make it possible for the producer to be smarter about setting the
> > tombstone. It would only do it if a tombstone was not passed
> explicitly,
> > the value was null and the topic was compacted. The main drawback is
> that
> > the producer would be getting a bit more data for each topic even
> though it
> > probably won't use it most of the time. Extending MetadataResponse to
> > return topic configs would be useful for other reasons as well, so
> that
> > part seems OK.
> >
> > In addition, for both proposals, we could consider adding warnings
> to the
> > documentation that the behaviour of the constructors that don't take
> a
> > tombstone would change in the next major release so that tombstone =
> false.
> > Not sure if this would be worth it though.
> >
> > Ismael
> >
> > On Sun, Dec 11, 2016 at 11:15 PM, Ewen Cheslack-Postava <
> e...@confluent.io
> > >
> > wrote:
> >
> > > Michael,
> > >
> > > It kind of depends on how you want to interpret the tombstone
> flag. If
> > it's
> > > purely a producer-facing Kafka-level thing that we treat as
> internal to
> > the
> > > broker and log cleaner once the record is sent, then your approach
> makes
> > > sense. You're just moving copying the null-indicates-delete
> behavior of
> > the
> > > old constructor into the tombstone flag.
> > >
> > > However, if you want this change to more generally decouple the
> idea of
> > > deletion and null values, then you are sometimes converting what
> might
> > be a
> > > completely valid null value that doesn't indicate deletion into a
> > > tombstone. Downstream applications could potentially handle these
> cases
> > > differently given the separation of deletion from value.
> > >
> > > I guess the question is if we want to try to support the latter
> even for
> > > topics where we have older produce requests. An example where this
> could
> > > come up is in something like a CDC Connector. If we try to support
> the
> > > semantic difference, a connector might write changes to Kafka
> using the
> > > tombstone flag to indicate when a row was truly deleted (vs an
> update
> > that
> > > sets it to null but still present; this probably makes more sense
> for CDC
> > > from document stores or extracting single columns). There are
> various
> > > reasons we might want to maintain the full log and not turn
> compaction on
> > > (or just use a time-based retention policy), but downstream
> applications
> > > might care to know the difference between a delete and a null
> value. In
> > > fact both versions of the same log (compacted and time-retention)
> could
> > be
> > > useful and I don't think it'll be uncommon to maintain both or use
> KIP-71
> > > to maintain a hybrid compacted/retention topic.
> > >
> > > -Ewen
> > >
> > > On Sun, Dec 11, 2016 at 1:18 PM, Michael Pearce <
> michael.pea...@ig.com>
> > > wrote:
> > >
> > > > Hi Jay,
> > > >
> > > > Why wouldn't that work, the tombstone value is only looked at by
> the
> > > > broker, on a topic configured for compaction as such is benign
> on non
> > > > compacted topics. This is as much as sending a null value
> currently
> > > >
> > > >
> > > > Regards
> > > > Mike
> > > >
> > > >
> > > >
> > > > Sent using OWA for iPhone
> > > > ________________________________________
> > > > From: Jay Kreps <j...@confluent.io>
> > > > Sent: Sunday, December 11, 2016 8:58:53 PM
> > > > To: dev@kafka.apache.org
> > > > Subject: Re: [VOTE] KIP-87 - Add Compaction Tombstone Flag
> > > >
> > > > Hey Michael,
> > > >
> > > > I'm not quite sure that works as that would translate ALL null
> values
> > to
> > > > tombstones, even for non-compacted topics that use null as an
> > acceptable
> > > > value sent by the producer and expected by the consumer.
> > > >
> > > > -Jay
> > > >
> > > > On Sun, Dec 11, 2016 at 3:26 AM, Michael Pearce <
> michael.pea...@ig.com
> > >
> > > > wrote:
> > > >
> > > > > Hi Ewen,
> > > > >
> > > > > I think the easiest way to show this is with code.
> > > > >
> > > > > As you can see we keep the existing behaviour for code/binaries
> > calling
> > > > > the pre-existing constructors, whereby if the value is null the
> > > tombstone
> > > > > is set to true.
> > > > >
> > > > > Regards
> > > > > Mike
> > > > >
> > > > >
> > > > >
> > > > > /**
> > > > > * Creates a record with a specified timestamp to be sent
> to a
> > > > > specified topic and partition
> > > > > *
> > > > > * @param topic The topic the record will be appended to
> > > > > * @param partition The partition to which the record
> should be
> > > sent
> > > > > * @param timestamp The timestamp of the record
> > > > > * @param tombstone if the record should be treated as a
> > tombstone
> > > if
> > > > > the topic is compacted
> > > > > * @param key The key that will be included in the record
> > > > > * @param value The record contents
> > > > > */
> > > > > public ProducerRecord(String topic, Integer partition,
> Boolean
> > > > > tombstone, Long timestamp, K key, V value) {
> > > > > if (topic == null)
> > > > > throw new IllegalArgumentException("Topic cannot
> be
> > > null.");
> > > > > if (timestamp != null && timestamp < 0)
> > > > > throw new IllegalArgumentException(
> > > > > String.format("Invalid timestamp: %d.
> Timestamp
> > > > should
> > > > > always be non-negative or null.", timestamp));
> > > > > if (partition != null && partition < 0)
> > > > > throw new IllegalArgumentException(
> > > > > String.format("Invalid partition: %d.
> Partition
> > > > number
> > > > > should always be non-negative or null.", partition));
> > > > > if (!tombstone && value == null){
> > > > > throw new IllegalArgumentException(
> > > > > String.format("Tombstone must be true if
> null
> > > > value"));
> > > > > }
> > > > > this.topic = topic;
> > > > > this.partition = partition;
> > > > > this.tombstone = tombstone;
> > > > > this.key = key;
> > > > > this.value = value;
> > > > > this.timestamp = timestamp;
> > > > > }
> > > > >
> > > > > public ProducerRecord(String topic, Integer partition, Long
> > > > timestamp,
> > > > > K key, V value) {
> > > > > this(topic, partition, value == null, timestamp, key,
> value);
> > > > > }
> > > > > ________________________________________
> > > > > From: Ewen Cheslack-Postava <e...@confluent.io>
> > > > > Sent: Sunday, December 11, 2016 5:45 AM
> > > > > To: dev@kafka.apache.org
> > > > > Subject: Re: [VOTE] KIP-87 - Add Compaction Tombstone Flag
> > > > >
> > > > > It seemed like this was addressed in the migration section,
> wasn't
> > it?
> > > > The
> > > > > V2 vs V3 requests and the fact that the broker will downgrade
> the
> > > message
> > > > > format (losing zero copy) if you issues a V2 request to a
> broker
> > using
> > > V3
> > > > > format handles compatibility, does it not? The existing
> consumers
> > won't
> > > > see
> > > > > the extra metadata in the value, but they will get a null
> instead and
> > > > treat
> > > > > it as a tombstone. Certainly there is a performance impact,
> but it
> > > seemed
> > > > > compatible.
> > > > >
> > > > > I'm worried about this though:
> > > > >
> > > > >
> > > > > - *NOTE *: With the new version of producer client using
> > > > ProduceRequest
> > > > > V3 (magic byte = 2), a non tombstone (tombstone bit not
> set) and
> > > null
> > > > > value
> > > > > should not be allowed as the older version of consumer using
> > > > > FetchRequest
> > > > > V2 will think of this as a tombstone when its actually not.
> > > > >
> > > > >
> > > > > Unless I'm misunderstanding, this ends up breaking binary
> > compatibility
> > > > for
> > > > > the Java API. It sounds like this suggests that passing a null
> value
> > to
> > > > the
> > > > > existing ProducerRecord constructors would generate an
> exception
> > since
> > > > you
> > > > > didn't explicitly enable the tombstone (via whatever new
> constructor
> > is
> > > > > provided). But that means you can't swap in a newer client jar
> > without
> > > > > recompiling and get the same behavior if your app deletes keys
> using
> > > the
> > > > > current approach because your app will start throwing
> exceptions.
> > Maybe
> > > > > this is a tradeoff we're ok with, but we've tried pretty hard
> to
> > avoid
> > > > > breaking compatibility like this so far -- it makes picking up
> bug
> > > fixes
> > > > in
> > > > > the clients harder for users of frameworks that have to pin to
> > earlier
> > > > > default versions for compatibility.
> > > > >
> > > > > But then later the KIP says:
> > > > >
> > > > >
> > > > > - The old constructors for ProducerRecord without this
> parameter
> > > will
> > > > be
> > > > > kept but updated so that their default behaviour if setting
> null
> > > value
> > > > > will
> > > > > be the tombstone will be set to true to keep existing
> behaviour.
> > > > >
> > > > >
> > > > > So maybe I am misinterpreting something.
> > > > >
> > > > > And just a nit re: motivation section, item 6 would be clearer
> for a
> > > > union
> > > > > schema with null (or optional schemas in other formats), e.g.
> [null,
> > > > > string], in which case losing the schema truly is losing
> information
> > > > > (whereas null is already the only valid value for a pure null
> > schema).
> > > > >
> > > > > -Ewen
> > > > >
> > > > >
> > > > > On Sat, Dec 10, 2016 at 9:24 PM, Michael Pearce <
> > michael.pea...@ig.com
> > > >
> > > > > wrote:
> > > > >
> > > > > > Hi Jay,
> > > > > >
> > > > > > Good point this detail is missing in the KIP write up. Ive
> added
> > this
> > > > > now.
> > > > > >
> > > > > > Essentially simply just upgrading the clients we do not
> expect any
> > > > client
> > > > > > app code change needed.
> > > > > >
> > > > > > Cheers
> > > > > > Mike
> > > > > > ________________________________________
> > > > > > From: Jay Kreps <j...@confluent.io>
> > > > > > Sent: Saturday, December 10, 2016 10:51 PM
> > > > > > To: dev@kafka.apache.org
> > > > > > Subject: Re: [VOTE] KIP-87 - Add Compaction Tombstone Flag
> > > > > >
> > > > > > Michael,
> > > > > >
> > > > > > The compatibility section goes through the migration path,
> but
> > isn't
> > > > the
> > > > > > bigger compatibility issue with existing apps? There are many
> > > (probably
> > > > > > thousands) of apps in production that use this feature and
> send
> > null
> > > to
> > > > > > mean delete. It seems like this would break compatibility
> with
> > them,
> > > > and
> > > > > > they would have to be rewritten to right?
> > > > > >
> > > > > > -Jay
> > > > > >
> > > > > > On Thu, Dec 8, 2016 at 12:12 AM, Michael Pearce <
> > > michael.pea...@ig.com
> > > > >
> > > > > > wrote:
> > > > > >
> > > > > > > Hi Jun,
> > > > > > >
> > > > > > > 4) On v3 we honour the tombstone. As such we expect it to
> be set
> > > > > > correctly
> > > > > > > as per the KIP.
> > > > > > >
> > > > > > > 4.1) why would we want to produce an error when its v3?
> This is
> > the
> > > > > exact
> > > > > > > purpose to support non-null tombstone’s
> > > > > > > 4.2) again here im unclear on the question on the v3,
> produce
> > > request
> > > > > we
> > > > > > > expect the tombstone flag to be set correctly.
> > > > > > >
> > > > > > > 4.4) compaction only occurs on compacted topics, the bit
> makes no
> > > > > > > difference and not looked at on un-compacted (time/size
> based
> > > > > eviction).
> > > > > > >
> > > > > > >
> > > > > > > On 06/12/2016, 20:08, "Jun Rao" <j...@confluent.io> wrote:
> > > > > > >
> > > > > > > Hi, Michael,
> > > > > > >
> > > > > > > 4. Then, I think I misunderstood this point. Could you
> > document
> > > > the
> > > > > > > following points in the wiki?
> > > > > > > 4.1 If producer V3 sets tombstone, but provides a
> non-null
> > > value,
> > > > > > does
> > > > > > > the
> > > > > > > send() get an error or does the producer automatically
> set
> > the
> > > > > value
> > > > > > to
> > > > > > > null?
> > > > > > > 4.2 If producer V3 doesn't set tombstone, but provides
> a null
> > > > > value,
> > > > > > > does
> > > > > > > the send() get an error or does the producer
> automatically
> > sets
> > > > the
> > > > > > > tombstone?
> > > > > > > 4.3 Does the broker only expect messages that (a) have
> no
> > > > tombstone
> > > > > > and
> > > > > > > non-null value; (b) have tombstone and null value and
> reject
> > > the
> > > > > > > messages
> > > > > > > with an error code otherwise?
> > > > > > > 4.4 Do 4.1, 4.2, 4.3 depend on whether the topic is
> > compacted
> > > on
> > > > > > not?
> > > > > > >
> > > > > > > Thanks,
> > > > > > >
> > > > > > > Jun
> > > > > > >
> > > > > > > On Tue, Dec 6, 2016 at 10:35 AM, Michael Pearce <
> > > > > > michael.pea...@ig.com
> > > > > > > >
> > > > > > > wrote:
> > > > > > >
> > > > > > > > Not at all. This only acts on compacted topics just
> as
> > what
> > > > > occurs
> > > > > > > today
> > > > > > > >
> > > > > > > > Sent using OWA for iPhone
> > > > > > > > ________________________________________
> > > > > > > > From: Jun Rao <j...@confluent.io>
> > > > > > > > Sent: Tuesday, December 6, 2016 6:25:28 PM
> > > > > > > > To: dev@kafka.apache.org
> > > > > > > > Subject: Re: [VOTE] KIP-87 - Add Compaction
> Tombstone Flag
> > > > > > > >
> > > > > > > > Hi, Michael,
> > > > > > > >
> > > > > > > > 4. Hmm, does that mean the new client library can
> never
> > send
> > > a
> > > > > null
> > > > > > > message
> > > > > > > > even to a regular topic? This seems like a change of
> the
> > > > existing
> > > > > > > behavior.
> > > > > > > >
> > > > > > > > Thanks,
> > > > > > > >
> > > > > > > > Jun
> > > > > > > >
> > > > > > > > On Tue, Dec 6, 2016 at 9:51 AM, Michael Pearce <
> > > > > > > michael.pea...@ig.com>
> > > > > > > > wrote:
> > > > > > > >
> > > > > > > > > Hi Jun,
> > > > > > > > >
> > > > > > > > > Re 4) That's because we expect the tombstone value
> to be
> > > set
> > > > > > > correctly if
> > > > > > > > > message bit is 2, as such if an older client sends
> in on
> > > old
> > > > > > > message the
> > > > > > > > > message is upcast and the bit is set correctly.
> And such
> > no
> > > > > > longer
> > > > > > > need
> > > > > > > > to
> > > > > > > > > check the value. Mayuresh can you confirm my
> thinking and
> > > > > > > understanding
> > > > > > > > of
> > > > > > > > > what we've discussed?
> > > > > > > > >
> > > > > > > > > The second point I understand what you're getting
> at now
> > my
> > > > > > > apologies.
> > > > > > > > Yes
> > > > > > > > > this makes sense to save on touching the message,
> if
> > we're
> > > > the
> > > > > > > only kip
> > > > > > > > > going in, in this release.
> > > > > > > > >
> > > > > > > > > Cheers
> > > > > > > > > Mike
> > > > > > > > >
> > > > > > > > > Sent using OWA for iPhone
> > > > > > > > > ________________________________________
> > > > > > > > > From: Jun Rao <j...@confluent.io>
> > > > > > > > > Sent: Tuesday, December 6, 2016 5:22:13 PM
> > > > > > > > > To: dev@kafka.apache.org
> > > > > > > > > Subject: Re: [VOTE] KIP-87 - Add Compaction
> Tombstone
> > Flag
> > > > > > > > >
> > > > > > > > > Hi, Michael,
> > > > > > > > >
> > > > > > > > > 4. Is this updated in the wiki? The text "If the
> magic
> > byte
> > > > on
> > > > > > > message is
> > > > > > > > > 2, the broker should use the tombstone bit for log
> > > > compaction."
> > > > > > > doesn't
> > > > > > > > > seem to have changed.
> > > > > > > > >
> > > > > > > > > 2. My point is that if we change the message
> format just
> > > for
> > > > > this
> > > > > > > KIP, we
> > > > > > > > > should consider whether it's worth optimizing the
> down
> > > > > conversion
> > > > > > > path
> > > > > > > > > (i.e., decide whether a conversion is needed by
> just
> > > looking
> > > > at
> > > > > > the
> > > > > > > > > tombstone bit in the wrapper message) since
> tombstone
> > will
> > > be
> > > > > > used
> > > > > > > > rarely.
> > > > > > > > > However, if the message format change here is
> combined
> > with
> > > > > other
> > > > > > > KIPs,
> > > > > > > > > then this optimization likely won't be needed. The
> latter
> > > > > > probably
> > > > > > > makes
> > > > > > > > > the code simpler. Jiangjie, Mayuresh, what do you
> think?
> > > > > > > > >
> > > > > > > > > Other than those, +1 from me,
> > > > > > > > >
> > > > > > > > > Thanks,
> > > > > > > > >
> > > > > > > > > Jun
> > > > > > > > >
> > > > > > > > > On Tue, Dec 6, 2016 at 8:54 AM, Michael Pearce <
> > > > > > > michael.pea...@ig.com>
> > > > > > > > > wrote:
> > > > > > > > >
> > > > > > > > > > Hi Jun
> > > > > > > > > >
> > > > > > > > > > do we have your vote on this now?
> > > > > > > > > >
> > > > > > > > > > Any other concerns?
> > > > > > > > > >
> > > > > > > > > > Cheers
> > > > > > > > > > Mike
> > > > > > > > > >
> > > > > > > > > > Sent using OWA for iPhone
> > > > > > > > > > ________________________________________
> > > > > > > > > > From: Michael Pearce <michael.pea...@ig.com>
> > > > > > > > > > Sent: Saturday, December 3, 2016 1:37:45 AM
> > > > > > > > > > To: dev@kafka.apache.org
> > > > > > > > > > Subject: Re: [VOTE] KIP-87 - Add Compaction
> Tombstone
> > > Flag
> > > > > > > > > >
> > > > > > > > > > Hi Jun,
> > > > > > > > > >
> > > > > > > > > > Have updated. Thanks again for the feedback.
> > > > > > > > > >
> > > > > > > > > > Agree yes we should align up when it gets to
> that, I
> > > assume
> > > > > > > you’ve
> > > > > > > > > flagged
> > > > > > > > > > the same in the other KIP?
> > > > > > > > > >
> > > > > > > > > > I think for now let’s get this KIP approved,
> then we
> > can
> > > > > start
> > > > > > > the work
> > > > > > > > > to
> > > > > > > > > > get an initial PR, then we can discuss how to
> align the
> > > two
> > > > > if
> > > > > > > needed.
> > > > > > > > > >
> > > > > > > > > > Cheers,
> > > > > > > > > > Mike
> > > > > > > > > >
> > > > > > > > > > On 02/12/2016, 18:26, "Jun Rao" <
> j...@confluent.io>
> > > wrote:
> > > > > > > > > >
> > > > > > > > > > Hi, Michael,
> > > > > > > > > >
> > > > > > > > > > For 2), this is fine. Could you update the
> KIP wiki
> > > to
> > > > > make
> > > > > > > this
> > > > > > > > and
> > > > > > > > > > other
> > > > > > > > > > points clearer? Other than that, the KIP
> looks good
> > > to
> > > > > me.
> > > > > > > > > >
> > > > > > > > > > An orthogonal thing is that there are other
> KIPs
> > such
> > > > as
> > > > > > > KIP-98
> > > > > > > > that
> > > > > > > > > > also
> > > > > > > > > > intend to change the message format. If they
> all
> > get
> > > > > > > approved, we
> > > > > > > > > > should
> > > > > > > > > > think about whether it's better to just bump
> up the
> > > > magic
> > > > > > > byte once
> > > > > > > > > to
> > > > > > > > > > incorporate multiple format changes like we
> did in
> > > > > > > KIP-31/KIP-32.
> > > > > > > > > >
> > > > > > > > > > Thanks,
> > > > > > > > > >
> > > > > > > > > > Jun
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > On Fri, Dec 2, 2016 at 3:19 AM, Michael
> Pearce <
> > > > > > > > > michael.pea...@ig.com>
> > > > > > > > > > wrote:
> > > > > > > > > >
> > > > > > > > > > > Hi Jao
> > > > > > > > > > >
> > > > > > > > > > > Thanks for the response. Sorry for slow
> reply,
> > both
> > > > > with
> > > > > > > personal
> > > > > > > > > > sickness
> > > > > > > > > > > and also battling some critical issues
> > encountered
> > > > > since
> > > > > > > > upgrading
> > > > > > > > > to
> > > > > > > > > > > 0.10.1.0
> > > > > > > > > > >
> > > > > > > > > > > 1) Thans for spotting, Document error
> where we
> > > > branched
> > > > > > > this KIP
> > > > > > > > > from
> > > > > > > > > > > KIP-82, will get that removed.
> > > > > > > > > > > 2) Intent is to do this just at the record
> > message
> > > > > level.
> > > > > > > > > > > 3) Thanks for spotting, Will ensure this is
> > > > corrected.
> > > > > > > > > > > 4) As per discussion thread we will support
> > > > tombstone +
> > > > > > > null
> > > > > > > > value,
> > > > > > > > > > > tombstone + non null value, no tombstone +
> null
> > > > value.
> > > > > > > > > > > 5) I believe this was in the discussion
> thread,
> > > > > @Mayuresh
> > > > > > > is this
> > > > > > > > > > > something we’ve overlooked? I thought we
> would
> > down
> > > > > > > convert and
> > > > > > > > > > remove the
> > > > > > > > > > > value so the old consumer had existing
> behavior,
> > or
> > > > is
> > > > > > > there
> > > > > > > > > > something we
> > > > > > > > > > > haven’t thought about?
> > > > > > > > > > >
> > > > > > > > > > > Cheers
> > > > > > > > > > > Mike
> > > > > > > > > > >
> > > > > > > > > > > On 30/11/2016, 18:12, "Jun Rao" <
> > j...@confluent.io>
> > > > > > wrote:
> > > > > > > > > > >
> > > > > > > > > > > Hi, Michael,
> > > > > > > > > > >
> > > > > > > > > > > Thanks for the KIP. A few comments
> below.
> > > > > > > > > > >
> > > > > > > > > > > 1. The message format change contains
> > > > > "HeadersLength
> > > > > > > > Headers".
> > > > > > > > > > Is that
> > > > > > > > > > > intended?
> > > > > > > > > > >
> > > > > > > > > > > 2. For compressed messageset, is the
> > tombstone
> > > > bit
> > > > > > > only set
> > > > > > > > at
> > > > > > > > > > the
> > > > > > > > > > > shallow
> > > > > > > > > > > level? Do we always leave that bit in
> the
> > > wrapper
> > > > > > > message
> > > > > > > > > unset?
> > > > > > > > > > An
> > > > > > > > > > > alternative is to set the tombstone
> bit in
> > the
> > > > > > wrapper
> > > > > > > if at
> > > > > > > > > > least one
> > > > > > > > > > > inner message has the tombstone bit
> set. This
> > > > makes
> > > > > > > things a
> > > > > > > > > bit
> > > > > > > > > > more
> > > > > > > > > > > complicated, but we could potentially
> exploit
> > > > that
> > > > > > for
> > > > > > > > > > optimizing down
> > > > > > > > > > > conversion. For example, we only need
> to
> > > convert
> > > > > > > messages
> > > > > > > > with
> > > > > > > > > > magic 2
> > > > > > > > > > > to
> > > > > > > > > > > magic 1 if the wrapper's tombstone bit
> is set
> > > > > > > (conversion is
> > > > > > > > > > always
> > > > > > > > > > > needed
> > > > > > > > > > > from magic 2 to magic 0). Not sure if
> the
> > > > > > optimization
> > > > > > > is
> > > > > > > > worth
> > > > > > > > > > the
> > > > > > > > > > > complexity though.
> > > > > > > > > > >
> > > > > > > > > > > 3. The referencing of the new version
> of
> > > > > > > > > > ProducerRequest/FetchRequest
> > > > > > > > > > > is
> > > > > > > > > > > inconsistent (v4 vs v3). Since our
> convention
> > > > > starts
> > > > > > at
> > > > > > > > version
> > > > > > > > > > at 0, I
> > > > > > > > > > > think the new version would be 3.
> > > > > > > > > > >
> > > > > > > > > > > 4. "If the magic byte on message is 2,
> the
> > > broker
> > > > > > > should use
> > > > > > > > > the
> > > > > > > > > > > tombstone
> > > > > > > > > > > bit for log compaction." What about
> null
> > value?
> > > > My
> > > > > > > > > understanding
> > > > > > > > > > is
> > > > > > > > > > > that
> > > > > > > > > > > null value will be treated the same as
> > setting
> > > > the
> > > > > > > tombstone
> > > > > > > > > bit.
> > > > > > > > > > >
> > > > > > > > > > > 5. For the migration path, it would be
> useful
> > > to
> > > > > > > describe the
> > > > > > > > > > down
> > > > > > > > > > > conversion path to consumers (i.e.,
> brokers
> > on
> > > > > > message
> > > > > > > format
> > > > > > > > > > 0.10.2
> > > > > > > > > > > and
> > > > > > > > > > > consumers on older version).
> > > > > > > > > > >
> > > > > > > > > > > Thanks,
> > > > > > > > > > >
> > > > > > > > > > > Jun
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > On Tue, Nov 29, 2016 at 3:18 AM,
> Michael
> > > Pearce <
> > > > > > > > > > michael.pea...@ig.com
> > > > > > > > > > > >
> > > > > > > > > > > wrote:
> > > > > > > > > > >
> > > > > > > > > > > > Hi All,
> > > > > > > > > > > >
> > > > > > > > > > > > We have been discussing in the below
> thread
> > > and
> > > > > > final
> > > > > > > > changes
> > > > > > > > > > have
> > > > > > > > > > > been
> > > > > > > > > > > > made to the KIP wiki based on these
> > > > discussions.
> > > > > > > > > > > >
> > > > > > > > > > > > We would now like to put to the vote
> the
> > > > > following
> > > > > > > KIP:
> > > > > > > > > > > > https://cwiki.apache.org/
> > > > > > > confluence/display/KAFKA/KIP-
> > > > > > > > 87+-+
> > > > > > > > > > > > Add+Compaction+Tombstone+Flag
> > > > > > > > > > > >
> > > > > > > > > > > > This kip is for having a distinct
> > compaction
> > > > > > > attribute
> > > > > > > > > > “tombstone”
> > > > > > > > > > > flag
> > > > > > > > > > > > instead of relying on null value,
> allowing
> > > > > non-null
> > > > > > > value
> > > > > > > > > > delete
> > > > > > > > > > > messages.
> > > > > > > > > > > >
> > > > > > > > > > > > Many thanks,
> > > > > > > > > > > > Michael
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > On 22/11/2016, 15:52, "Michael
> Pearce" <
> > > > > > > > > michael.pea...@ig.com>
> > > > > > > > > > > wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > Hi Mayuresh,
> > > > > > > > > > > >
> > > > > > > > > > > > LGTM. Ive just made one small
> > adjustment
> > > > > > > updating the
> > > > > > > > > wire
> > > > > > > > > > > protocol to
> > > > > > > > > > > > show the magic byte bump.
> > > > > > > > > > > >
> > > > > > > > > > > > Do we think we’re good to put to
> a
> > vote?
> > > Is
> > > > > > > there any
> > > > > > > > > > other bits
> > > > > > > > > > > > needing discussion?
> > > > > > > > > > > >
> > > > > > > > > > > > Cheers
> > > > > > > > > > > > Mike
> > > > > > > > > > > >
> > > > > > > > > > > > On 21/11/2016, 18:26, "Mayuresh
> > Gharat" <
> > > > > > > > > > > gharatmayures...@gmail.com>
> > > > > > > > > > > > wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > Hi Michael,
> > > > > > > > > > > >
> > > > > > > > > > > > I have updated the migration
> > section
> > > of
> > > > > the
> > > > > > > KIP.
> > > > > > > > Can
> > > > > > > > > > you
> > > > > > > > > > > please
> > > > > > > > > > > > take a look?
> > > > > > > > > > > >
> > > > > > > > > > > > Thanks,
> > > > > > > > > > > >
> > > > > > > > > > > > Mayuresh
> > > > > > > > > > > >
> > > > > > > > > > > > On Fri, Nov 18, 2016 at 9:07
> AM,
> > > > Mayuresh
> > > > > > > Gharat <
> > > > > > > > > > > > gharatmayures...@gmail.com
> > > > > > > > > > > > > wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > > Hi Michael,
> > > > > > > > > > > > >
> > > > > > > > > > > > > That whilst sending
> tombstone and
> > > non
> > > > > > null
> > > > > > > value,
> > > > > > > > > the
> > > > > > > > > > > consumer
> > > > > > > > > > > > can expect
> > > > > > > > > > > > > only to receive the
> non-null
> > > message
> > > > > only
> > > > > > > in step
> > > > > > > > > > (3) is
> > > > > > > > > > > this
> > > > > > > > > > > > correct?
> > > > > > > > > > > > > ---> I do agree with you
> here.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Becket, Ismael : can you
> guys
> > > review
> > > > > the
> > > > > > > > migration
> > > > > > > > > > plan
> > > > > > > > > > > listed
> > > > > > > > > > > > above using
> > > > > > > > > > > > > magic byte?
> > > > > > > > > > > > >
> > > > > > > > > > > > > Thanks,
> > > > > > > > > > > > >
> > > > > > > > > > > > > Mayuresh
> > > > > > > > > > > > >
> > > > > > > > > > > > > On Fri, Nov 18, 2016 at
> 8:58 AM,
> > > > > Michael
> > > > > > > Pearce <
> > > > > > > > > > > > michael.pea...@ig.com>
> > > > > > > > > > > > > wrote:
> > > > > > > > > > > > >
> > > > > > > > > > > > >> Many thanks for this
> Mayuresh. I
> > > > don't
> > > > > > > have any
> > > > > > > > > > > objections.
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> I assume we should state:
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> That whilst sending
> tombstone
> > and
> > > > non
> > > > > > null
> > > > > > > > value,
> > > > > > > > > > the
> > > > > > > > > > > consumer
> > > > > > > > > > > > can expect
> > > > > > > > > > > > >> only to receive the
> non-null
> > > message
> > > > > > only
> > > > > > > in
> > > > > > > > step
> > > > > > > > > > (3) is
> > > > > > > > > > > this
> > > > > > > > > > > > correct?
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> Cheers
> > > > > > > > > > > > >> Mike
> > > > > > > > > > > > >>
> > > > > > > > > > > > >>
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> Sent using OWA for iPhone
> > > > > > > > > > > > >>
> ______________________________
> > > > > > __________
> > > > > > > > > > > > >> From: Mayuresh Gharat <
> > > > > > > > gharatmayures...@gmail.com
> > > > > > > > > >
> > > > > > > > > > > > >> Sent: Thursday, November
> 17,
> > 2016
> > > > > > 5:18:41
> > > > > > > PM
> > > > > > > > > > > > >> To: dev@kafka.apache.org
> > > > > > > > > > > > >> Subject: Re: [DISCUSS]
> KIP-87 -
> > > Add
> > > > > > > Compaction
> > > > > > > > > > Tombstone
> > > > > > > > > > > Flag
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> Hi Ismael,
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> Thanks for the
> explanation.
> > > > > > > > > > > > >> Specially I like this
> part where
> > > in
> > > > > you
> > > > > > > > mentioned
> > > > > > > > > > we can
> > > > > > > > > > > get
> > > > > > > > > > > > rid of the
> > > > > > > > > > > > >> older null value support
> for log
> > > > > > > compaction
> > > > > > > > later
> > > > > > > > > > on,
> > > > > > > > > > > here :
> > > > > > > > > > > > >> We can't change semantics
> of the
> > > > > message
> > > > > > > format
> > > > > > > > > > without
> > > > > > > > > > > having
> > > > > > > > > > > > a long
> > > > > > > > > > > > >> transition period. And we
> can't
> > > rely
> > > > > > > > > > > > >> on people reading
> documentation
> > or
> > > > > > acting
> > > > > > > on a
> > > > > > > > > > warning for
> > > > > > > > > > > > something so
> > > > > > > > > > > > >> fundamental. As such, my
> take is
> > > > that
> > > > > we
> > > > > > > need to
> > > > > > > > > > bump the
> > > > > > > > > > > magic
> > > > > > > > > > > > byte. The
> > > > > > > > > > > > >> good news is
> > > > > > > > > > > > >> that we don't have to
> support
> > all
> > > > > > versions
> > > > > > > > > forever.
> > > > > > > > > > We
> > > > > > > > > > > have
> > > > > > > > > > > > said that we
> > > > > > > > > > > > >> will support direct
> upgrades
> > for 2
> > > > > > years.
> > > > > > > That
> > > > > > > > > > means that
> > > > > > > > > > > > message format
> > > > > > > > > > > > >> version n could, in
> theory, be
> > > > > removed 2
> > > > > > > years
> > > > > > > > > > after the
> > > > > > > > > > > it's
> > > > > > > > > > > > introduced.
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> Just a heads up, I would
> like to
> > > > > mention
> > > > > > > that
> > > > > > > > even
> > > > > > > > > > without
> > > > > > > > > > > > bumping magic
> > > > > > > > > > > > >> byte, we will *NOT* loose
> zero
> > > copy
> > > > as
> > > > > > in
> > > > > > > the
> > > > > > > > > > client(x+1)
> > > > > > > > > > > in my
> > > > > > > > > > > > >> explanation
> > > > > > > > > > > > >> above will convert
> internally a
> > > null
> > > > > > > value to
> > > > > > > > > have a
> > > > > > > > > > > tombstone
> > > > > > > > > > > > bit set and
> > > > > > > > > > > > >> a tombstone bit set to
> have a
> > null
> > > > > value
> > > > > > > > > > automatically
> > > > > > > > > > > > internally and by
> > > > > > > > > > > > >> the time we move to
> version
> > (x+2),
> > > > the
> > > > > > > clients
> > > > > > > > > > would have
> > > > > > > > > > > > upgraded.
> > > > > > > > > > > > >> Obviously if we support a
> > request
> > > > from
> > > > > > > > > consumer(x),
> > > > > > > > > > we
> > > > > > > > > > > will
> > > > > > > > > > > > loose zero
> > > > > > > > > > > > >> copy
> > > > > > > > > > > > >> but that is the same case
> with
> > > magic
> > > > > > byte.
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> But if magic byte bump
> makes
> > life
> > > > > easier
> > > > > > > for
> > > > > > > > > > transition
> > > > > > > > > > > for the
> > > > > > > > > > > > above
> > > > > > > > > > > > >> reasons that you
> explained, I am
> > > OK
> > > > > with
> > > > > > > it
> > > > > > > > since
> > > > > > > > > > we are
> > > > > > > > > > > going
> > > > > > > > > > > > to meet the
> > > > > > > > > > > > >> end goal down the road :)
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> On a side note can we
> update the
> > > doc
> > > > > > here
> > > > > > > on
> > > > > > > > magic
> > > > > > > > > > byte
> > > > > > > > > > > to say
> > > > > > > > > > > > that "*it
> > > > > > > > > > > > >> should be bumped whenever
> the
> > > > message
> > > > > > > format is
> > > > > > > > > > changed
> > > > > > > > > > > or the
> > > > > > > > > > > > >> interpretation of message
> format
> > > > > (usage
> > > > > > > of the
> > > > > > > > > > reserved
> > > > > > > > > > > bits as
> > > > > > > > > > > > well) is
> > > > > > > > > > > > >> changed*".
> > > > > > > > > > > > >>
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> Hi Michael,
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> Here is the update plan
> that we
> > > > > > discussed
> > > > > > > > offline
> > > > > > > > > > > yesterday :
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> Currently the magic-byte
> which
> > > > > > > corresponds to
> > > > > > > > the
> > > > > > > > > > > > "message.format.version"
> > > > > > > > > > > > >> is set to 1.
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> 1) On broker it will be
> set to 1
> > > > > > > initially.
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> 2) When a producer client
> sends
> > a
> > > > > > message
> > > > > > > with
> > > > > > > > > > magic-byte
> > > > > > > > > > > = 2,
> > > > > > > > > > > > since the
> > > > > > > > > > > > >> broker is on magic-byte =
> 1, we
> > > will
> > > > > > down
> > > > > > > > convert
> > > > > > > > > > it,
> > > > > > > > > > > which
> > > > > > > > > > > > means if the
> > > > > > > > > > > > >> tombstone bit is set, the
> value
> > > will
> > > > > be
> > > > > > > set to
> > > > > > > > > > null. A
> > > > > > > > > > > consumer
> > > > > > > > > > > > >> understanding magic-byte
> = 1,
> > will
> > > > > still
> > > > > > > work
> > > > > > > > with
> > > > > > > > > > this. A
> > > > > > > > > > > > consumer
> > > > > > > > > > > > >> working
> > > > > > > > > > > > >> with magic-byte =2 will
> also be
> > > able
> > > > > to
> > > > > > > > understand
> > > > > > > > > > this,
> > > > > > > > > > > since
> > > > > > > > > > > > it
> > > > > > > > > > > > >> understands the tombstone.
> > > > > > > > > > > > >> Now there is still the
> question
> > of
> > > > > > > supporting a
> > > > > > > > > > > non-tombstone
> > > > > > > > > > > > and null
> > > > > > > > > > > > >> value from producer
> client with
> > > > > > > magic-byte = 2.*
> > > > > > > > > (I
> > > > > > > > > > am
> > > > > > > > > > > not sure
> > > > > > > > > > > > if we
> > > > > > > > > > > > >> should support this.
> > Ismael/Becket
> > > > can
> > > > > > > comment
> > > > > > > > > > here)*
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> 3) When almost all the
> clients
> > > have
> > > > > > > upgraded,
> > > > > > > > the
> > > > > > > > > > > > message.format.version
> > > > > > > > > > > > >> on
> > > > > > > > > > > > >> the broker can be changed
> to 2,
> > > > where
> > > > > in
> > > > > > > the
> > > > > > > > down
> > > > > > > > > > > conversion in
> > > > > > > > > > > > the above
> > > > > > > > > > > > >> step will not happen. If
> at this
> > > > point
> > > > > > we
> > > > > > > get a
> > > > > > > > > > consumer
> > > > > > > > > > > > request from a
> > > > > > > > > > > > >> older consumer, we might
> have to
> > > > down
> > > > > > > convert
> > > > > > > > > where
> > > > > > > > > > in we
> > > > > > > > > > > loose
> > > > > > > > > > > > zero copy,
> > > > > > > > > > > > >> but these cases should be
> rare.
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> Becket can you review
> this plan
> > > and
> > > > > add
> > > > > > > more
> > > > > > > > > > details if I
> > > > > > > > > > > have
> > > > > > > > > > > > >> missed/wronged something,
> before
> > > we
> > > > > put
> > > > > > > it on
> > > > > > > > KIP.
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> Thanks,
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> Mayuresh
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> On Wed, Nov 16, 2016 at
> 11:07
> > PM,
> > > > > > Michael
> > > > > > > > Pearce <
> > > > > > > > > > > > michael.pea...@ig.com>
> > > > > > > > > > > > >> wrote:
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> > Thanks guys, for
> discussing
> > this
> > > > > > > offline and
> > > > > > > > > > getting
> > > > > > > > > > > some
> > > > > > > > > > > > consensus.
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > So its clear for myself
> and
> > > others
> > > > > > what
> > > > > > > is
> > > > > > > > > > proposed now
> > > > > > > > > > > (i
> > > > > > > > > > > > think i
> > > > > > > > > > > > >> > understand, but want to
> make
> > > sure)
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > Could i ask either
> directly
> > > update
> > > > > the
> > > > > > > kip to
> > > > > > > > > > detail the
> > > > > > > > > > > > migration
> > > > > > > > > > > > >> > strategy, or (re-)state
> your
> > > > offline
> > > > > > > discussed
> > > > > > > > > and
> > > > > > > > > > > agreed
> > > > > > > > > > > > migration
> > > > > > > > > > > > >> > strategy based on a
> magic byte
> > > is
> > > > in
> > > > > > > this
> > > > > > > > > thread.
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > The main original
> driver for
> > the
> > > > KIP
> > > > > > > was to
> > > > > > > > > > support
> > > > > > > > > > > > compaction where
> > > > > > > > > > > > >> value
> > > > > > > > > > > > >> > isn't null, based off
> the
> > > > > discussions
> > > > > > on
> > > > > > > > KIP-82
> > > > > > > > > > thread.
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > We should be able to
> support
> > > > > > > non-tombstone +
> > > > > > > > > null
> > > > > > > > > > value
> > > > > > > > > > > by the
> > > > > > > > > > > > >> completion
> > > > > > > > > > > > >> > of the KIP, as we noted
> when
> > > > > > discussing
> > > > > > > this
> > > > > > > > > kip,
> > > > > > > > > > having
> > > > > > > > > > > > logic based on
> > > > > > > > > > > > >> a
> > > > > > > > > > > > >> > null value isn't very
> clean
> > and
> > > > also
> > > > > > > separates
> > > > > > > > > the
> > > > > > > > > > > concerns.
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > As discussed already
> though we
> > > can
> > > > > > > split this
> > > > > > > > > into
> > > > > > > > > > > KIP-87a
> > > > > > > > > > > > and KIP-87b
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > Where we look to deliver
> > KIP-87a
> > > > on
> > > > > a
> > > > > > > > compacted
> > > > > > > > > > topic
> > > > > > > > > > > (to
> > > > > > > > > > > > address the
> > > > > > > > > > > > >> > immediate issues)
> > > > > > > > > > > > >> > * tombstone + null value
> > > > > > > > > > > > >> > * tombstone + non-null
> value
> > > > > > > > > > > > >> > * non-tombstone +
> non-null
> > value
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > Then we can discuss once
> > KIP-87a
> > > > is
> > > > > > > completed
> > > > > > > > > > options
> > > > > > > > > > > later
> > > > > > > > > > > > and how we
> > > > > > > > > > > > >> > support the second part
> > KIP-87b
> > > to
> > > > > > > deliver:
> > > > > > > > > > > > >> > * non-tombstone + null
> value
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > Cheers
> > > > > > > > > > > > >> > Mike
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> >
> ______________________________
> > > > > > > __________
> > > > > > > > > > > > >> > From: Becket Qin <
> > > > > > becket....@gmail.com>
> > > > > > > > > > > > >> > Sent: Thursday,
> November 17,
> > > 2016
> > > > > 1:43
> > > > > > > AM
> > > > > > > > > > > > >> > To:
> dev@kafka.apache.org
> > > > > > > > > > > > >> > Subject: Re: [DISCUSS]
> KIP-87
> > -
> > > > Add
> > > > > > > Compaction
> > > > > > > > > > > Tombstone Flag
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > Renu, Mayuresh and I
> had an
> > > > offline
> > > > > > > > discussion,
> > > > > > > > > > and
> > > > > > > > > > > following
> > > > > > > > > > > > is a brief
> > > > > > > > > > > > >> > summary.
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > 1. We agreed that not
> bumping
> > up
> > > > > magic
> > > > > > > value
> > > > > > > > may
> > > > > > > > > > result
> > > > > > > > > > > in
> > > > > > > > > > > > losing zero
> > > > > > > > > > > > >> copy
> > > > > > > > > > > > >> > during migration.
> > > > > > > > > > > > >> > 2. Given that bumping
> up magic
> > > > value
> > > > > > is
> > > > > > > almost
> > > > > > > > > > free and
> > > > > > > > > > > has
> > > > > > > > > > > > benefit of
> > > > > > > > > > > > >> > avoiding potential
> performance
> > > > > issue.
> > > > > > > It is
> > > > > > > > > > probably
> > > > > > > > > > > worth
> > > > > > > > > > > > doing.
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > One issue we still need
> to
> > think
> > > > > about
> > > > > > > is
> > > > > > > > > whether
> > > > > > > > > > we
> > > > > > > > > > > want to
> > > > > > > > > > > > support a
> > > > > > > > > > > > >> > non-tombstone message
> with
> > null
> > > > > value.
> > > > > > > > > > > > >> > Currently it is not
> supported
> > by
> > > > > > Kafka.
> > > > > > > If we
> > > > > > > > > > allow a
> > > > > > > > > > > > non-tombstone null
> > > > > > > > > > > > >> > value message to exist
> after
> > > > KIP-87.
> > > > > > The
> > > > > > > > problem
> > > > > > > > > > is
> > > > > > > > > > > that such
> > > > > > > > > > > > message
> > > > > > > > > > > > >> will
> > > > > > > > > > > > >> > not be supported by the
> > > consumers
> > > > > > prior
> > > > > > > to
> > > > > > > > > KIP-87.
> > > > > > > > > > > Because a
> > > > > > > > > > > > null value
> > > > > > > > > > > > >> > will always be
> interpreted to
> > a
> > > > > > > tombstone.
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > One option is that we
> keep the
> > > > > current
> > > > > > > way,
> > > > > > > > i.e.
> > > > > > > > > > do not
> > > > > > > > > > > > support such
> > > > > > > > > > > > >> > message. It would be
> good to
> > > know
> > > > if
> > > > > > > there is
> > > > > > > > a
> > > > > > > > > > > concrete use
> > > > > > > > > > > > case for
> > > > > > > > > > > > >> such
> > > > > > > > > > > > >> > message. If there is
> not, we
> > can
> > > > > > > probably just
> > > > > > > > > not
> > > > > > > > > > > support it.
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > Thanks,
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > JIangjie (Becket) Qin
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > On Wed, Nov 16, 2016 at
> 1:28
> > PM,
> > > > > > > Mayuresh
> > > > > > > > > Gharat <
> > > > > > > > > > > > >> >
> gharatmayures...@gmail.com
> > > > > > > > > > > > >> > > wrote:
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >> > > Hi Ismael,
> > > > > > > > > > > > >> > >
> > > > > > > > > > > > >> > > This is something I
> can
> > think
> > > of
> > > > > for
> > > > > > > > migration
> > > > > > > > > > plan:
> > > > > > > > > > > > >> > > So the migration plan
> can
> > look
> > > > > > > something
> > > > > > > > like
> > > > > > > > > > this,
> > > > > > > > > > > with up
> > > > > > > > > > > > >> conversion :
> > > > > > > > > > > > >> > >
> > > > > > > > > > > > >> > > 1) Currently lets say
> we
> > have
> > > > > Broker
> > > > > > > at
> > > > > > > > > version
> > > > > > > > > > x.
> > > > > > > > > > > > >> > > 2) Currently we have
> clients
> > > at
> > > > > > > version x.
> > > > > > > > > > > > >> > > 3) a) We move the
> version to
> > > > > > > Broker(x+1) :
> > > > > > > > > > supports
> > > > > > > > > > > both
> > > > > > > > > > > > tombstone and
> > > > > > > > > > > > >> > null
> > > > > > > > > > > > >> > > for log compaction.
> > > > > > > > > > > > >> > > b) We upgrade the
> client
> > > to
> > > > > > > version
> > > > > > > > > > client(x+1) :
> > > > > > > > > > > if in
> > > > > > > > > > > > the
> > > > > > > > > > > > >> producer
> > > > > > > > > > > > >> > > client(x+1) the value
> is set
> > > to
> > > > > > null,
> > > > > > > we
> > > > > > > > will
> > > > > > > > > > > automatically
> > > > > > > > > > > > set the
> > > > > > > > > > > > >> > > Tombstone bit
> internally. If
> > > the
> > > > > > > producer
> > > > > > > > > > client(x+1)
> > > > > > > > > > > sets
> > > > > > > > > > > > the
> > > > > > > > > > > > >> tombstone
> > > > > > > > > > > > >> > > itself, well and
> good. For
> > > > > producer
> > > > > > > > client(x),
> > > > > > > > > > the
> > > > > > > > > > > broker
> > > > > > > > > > > > will up
> > > > > > > > > > > > >> convert
> > > > > > > > > > > > >> > > to have the tombstone
> bit.
> > > > > > > Broker(x+1) is
> > > > > > > > > > supporting
> > > > > > > > > > > both.
> > > > > > > > > > > > Consumer
> > > > > > > > > > > > >> > > client(x+1) will be
> aware of
> > > > this
> > > > > > and
> > > > > > > should
> > > > > > > > > be
> > > > > > > > > > able
> > > > > > > > > > > to
> > > > > > > > > > > > handle this.
> > > > > > > > > > > > >> For
> > > > > > > > > > > > >> > > consumer client(x) we
> will
> > > down
> > > > > > > convert the
> > > > > > > > > > message
> > > > > > > > > > > on the
> > > > > > > > > > > > broker
> > > > > > > > > > > > >> side.
> > > > > > > > > > > > >> > > c) At this point
> we will
> > > > have
> > > > > to
> > > > > > > > specify a
> > > > > > > > > > > warning or
> > > > > > > > > > > > clearly
> > > > > > > > > > > > >> specify
> > > > > > > > > > > > >> > > in docs that this
> behavior
> > is
> > > > > about
> > > > > > > to be
> > > > > > > > > > changed for
> > > > > > > > > > > log
> > > > > > > > > > > > compaction.
> > > > > > > > > > > > >> > > 4) a) In next release
> of the
> > > > > > > Broker(x+2), we
> > > > > > > > > > say that
> > > > > > > > > > > only
> > > > > > > > > > > > Tombstone
> > > > > > > > > > > > >> is
> > > > > > > > > > > > >> > > used for log
> compaction on
> > the
> > > > > > Broker
> > > > > > > side.
> > > > > > > > > > > Clients(x+1)
> > > > > > > > > > > > still is
> > > > > > > > > > > > >> > > supported.
> > > > > > > > > > > > >> > > b) We upgrade the
> client
> > > to
> > > > > > > version
> > > > > > > > > > client(x+2) :
> > > > > > > > > > > if
> > > > > > > > > > > > value is set
> > > > > > > > > > > > >> to
> > > > > > > > > > > > >> > > null, tombstone will
> not be
> > > set
> > > > > > > > automatically.
> > > > > > > > > > The
> > > > > > > > > > > client
> > > > > > > > > > > > will have to
> > > > > > > > > > > > >> > call
> > > > > > > > > > > > >> > > setTombstone() to
> actually
> > set
> > > > the
> > > > > > > > tombstone.
> > > > > > > > > > > > >> > >
> > > > > > > > > > > > >> > > We should compare this
> > > migration
> > > > > > plan
> > > > > > > with
> > > > > > > > the
> > > > > > > > > > > migration
> > > > > > > > > > > > plan for
> > > > > > > > > > > > >> magic
> > > > > > > > > > > > >> > > byte bump and do
> whatever
> > > looks
> > > > > > good.
> > > > > > > > > > > > >> > > I am just worried
> that if we
> > > go
> > > > > down
> > > > > > > magic
> > > > > > > > > byte
> > > > > > > > > > route,
> > > > > > > > > > > > unless I am
> > > > > > > > > > > > >> > missing
> > > > > > > > > > > > >> > > something, it sounds
> like
> > > kafka
> > > > > will
> > > > > > > be
> > > > > > > > stuck
> > > > > > > > > > with
> > > > > > > > > > > > supporting both
> > > > > > > > > > > > >> null
> > > > > > > > > > > > >> > > value and tombstone
> bit for
> > > log
> > > > > > > compaction
> > > > > > > > for
> > > > > > > > > > life
> > > > > > > > > > > long,
> > > > > > > > > > > > which does
> > > > > > > > > > > > >> not
> > > > > > > > > > > > >> > > look like a good end
> state.
> > > > > > > > > > > > >> > >
> > > > > > > > > > > > >> > > Thanks,
> > > > > > > > > > > > >> > >
> > > > > > > > > > > > >> > > Mayuresh
> > > > > > > > > > > > >> > >
> > > > > > > > > > > > >> > >
> > > > > > > > > > > > >> > >
> > > > > > > > > > > > >> > >
> > > > > > > > > > > > >> > > On Wed, Nov 16, 2016
> at 9:32
> > > AM,
> > > > > > > Mayuresh
> > > > > > > > > > Gharat <
> > > > > > > > > > > > >> > >
> gharatmayures...@gmail.com
> > > > > > > > > > > > >> > > > wrote:
> > > > > > > > > > > > >> > >
> > > > > > > > > > > > >> > > > Hi Ismael,
> > > > > > > > > > > > >> > > >
> > > > > > > > > > > > >> > > > That's a very good
> point
> > > > which I
> > > > > > > might
> > > > > > > > have
> > > > > > > > > > not
> > > > > > > > > > > > considered earlier.
> > > > > > > > > > > > >> > > >
> > > > > > > > > > > > >> > > > Here is a plan that
> I can
> > > > think
> > > > > > of:
> > > > > > > > > > > > >> > > >
> > > > > > > > > > > > >> > > > Stage 1) The broker
> from
> > now
> > > > on,
> > > > > > up
> > > > > > > > converts
> > > > > > > > > > the
> > > > > > > > > > > message
> > > > > > > > > > > > to have the
> > > > > > > > > > > > >> > > > tombstone marker.
> The log
> > > > > > compaction
> > > > > > > > thread
> > > > > > > > > > does log
> > > > > > > > > > > > compaction
> > > > > > > > > > > > >> based
> > > > > > > > > > > > >> > on
> > > > > > > > > > > > >> > > > both null and
> tombstone
> > > > marker.
> > > > > > > This is
> > > > > > > > our
> > > > > > > > > > > transition
> > > > > > > > > > > > period.
> > > > > > > > > > > > >> > > > Stage 2) The next
> release
> > we
> > > > > only
> > > > > > > say that
> > > > > > > > > log
> > > > > > > > > > > compaction
> > > > > > > > > > > > is based
> > > > > > > > > > > > >> on
> > > > > > > > > > > > >> > > > tombstone marker.
> (Open
> > > source
> > > > > > > kafka makes
> > > > > > > > > > this as a
> > > > > > > > > > > > policy). By
> > > > > > > > > > > > >> this
> > > > > > > > > > > > >> > > time,
> > > > > > > > > > > > >> > > > the organization
> which is
> > > > moving
> > > > > > to
> > > > > > > this
> > > > > > > > > > release
> > > > > > > > > > > will be
> > > > > > > > > > > > sure that
> > > > > > > > > > > > >> they
> > > > > > > > > > > > >> > > > have gone through
> the
> > entire
> > > > > > > transition
> > > > > > > > > > period.
> > > > > > > > > > > > >> > > >
> > > > > > > > > > > > >> > > > My only goal of
> doing this
> > > is
> > > > > that
> > > > > > > Kafka
> > > > > > > > > > clearly
> > > > > > > > > > > > specifies the end
> > > > > > > > > > > > >> > state
> > > > > > > > > > > > >> > > > about what log
> compaction
> > > > means
> > > > > > (is
> > > > > > > it
> > > > > > > > null
> > > > > > > > > > value
> > > > > > > > > > > or a
> > > > > > > > > > > > tombstone
> > > > > > > > > > > > >> > marker,
> > > > > > > > > > > > >> > > > but not both).
> > > > > > > > > > > > >> > > >
> > > > > > > > > > > > >> > > > What do you think?
> > > > > > > > > > > > >> > > >
> > > > > > > > > > > > >> > > > Thanks,
> > > > > > > > > > > > >> > > >
> > > > > > > > > > > > >> > > > Mayuresh
> > > > > > > > > > > > >> > > > .
> > > > > > > > > > > > >> > > >
> > > > > > > > > > > > >> > > > On Wed, Nov 16,
> 2016 at
> > 9:17
> > > > AM,
> > > > > > > Ismael
> > > > > > > > > Juma <
> > > > > > > > > > > > ism...@juma.me.uk>
> > > > > > > > > > > > >> > wrote:
> > > > > > > > > > > > >> > > >
> > > > > > > > > > > > >> > > >> One comment below.
> > > > > > > > > > > > >> > > >>
> > > > > > > > > > > > >> > > >> On Wed, Nov 16,
> 2016 at
> > > 5:08
> > > > > PM,
> > > > > > > Mayuresh
> > > > > > > > > > Gharat <
> > > > > > > > > > > > >> > > >>
> > gharatmayures...@gmail.com
> > > > > > > > > > > > >> > > >> > wrote:
> > > > > > > > > > > > >> > > >>
> > > > > > > > > > > > >> > > >> > - If we don't
> bump
> > up
> > > > the
> > > > > > > magic
> > > > > > > > byte,
> > > > > > > > > > on the
> > > > > > > > > > > broker
> > > > > > > > > > > > side, the
> > > > > > > > > > > > >> > > broker
> > > > > > > > > > > > >> > > >> > will always
> have to
> > > look
> > > > > at
> > > > > > > both
> > > > > > > > > > tombstone
> > > > > > > > > > > bit and
> > > > > > > > > > > > the value
> > > > > > > > > > > > >> when
> > > > > > > > > > > > >> > > do
> > > > > > > > > > > > >> > > >> the
> > > > > > > > > > > > >> > > >> > compaction.
> Assuming
> > > we
> > > > do
> > > > > > > not bump
> > > > > > > > up
> > > > > > > > > > the
> > > > > > > > > > > magic
> > > > > > > > > > > > byte,
> > > > > > > > > > > > >> > > >> > imagine the
> broker
> > > sees
> > > > a
> > > > > > > message
> > > > > > > > > which
> > > > > > > > > > does
> > > > > > > > > > > not
> > > > > > > > > > > > have a
> > > > > > > > > > > > >> tombstone
> > > > > > > > > > > > >> > > bit
> > > > > > > > > > > > >> > > >> > set. The
> broker does
> > > not
> > > > > > know
> > > > > > > when
> > > > > > > > the
> > > > > > > > > > > message was
> > > > > > > > > > > > produced
> > > > > > > > > > > > >> (i.e.
> > > > > > > > > > > > >> > > >> > whether
> > > > > > > > > > > > >> > > >> > the message
> has been
> > > up
> > > > > > > converted or
> > > > > > > > > > not), it
> > > > > > > > > > > has
> > > > > > > > > > > > to take a
> > > > > > > > > > > > >> > further
> > > > > > > > > > > > >> > > >> > look at
> > > > > > > > > > > > >> > > >> > the value to
> see if
> > it
> > > > is
> > > > > > > null or
> > > > > > > > not
> > > > > > > > > in
> > > > > > > > > > > order to
> > > > > > > > > > > > determine
> > > > > > > > > > > > >> if it
> > > > > > > > > > > > >> > > is
> > > > > > > > > > > > >> > > >> a
> > > > > > > > > > > > >> > > >> > tombstone.
> The same
> > > > logic
> > > > > > has
> > > > > > > to be
> > > > > > > > > put
> > > > > > > > > > on the
> > > > > > > > > > > > consumer as
> > > > > > > > > > > > >> well
> > > > > > > > > > > > >> > > >> because
> > > > > > > > > > > > >> > > >> > the
> > > > > > > > > > > > >> > > >> > consumer does
> not
> > know
> > > > if
> > > > > > the
> > > > > > > > message
> > > > > > > > > > has
> > > > > > > > > > > been up
> > > > > > > > > > > > converted or
> > > > > > > > > > > > >> > not.
> > > > > > > > > > > > >> > > >> > - If we
> upconvert
> > > > while
> > > > > > > > appending,
> > > > > > > > > > this is
> > > > > > > > > > > not
> > > > > > > > > > > > the case,
> > > > > > > > > > > > >> > right?
> > > > > > > > > > > > >> > > >>
> > > > > > > > > > > > >> > > >>
> > > > > > > > > > > > >> > > >> If I understand you
> > > > correctly,
> > > > > > > this is
> > > > > > > > not
> > > > > > > > > > > sufficient
> > > > > > > > > > > > because the
> > > > > > > > > > > > >> log
> > > > > > > > > > > > >> > > may
> > > > > > > > > > > > >> > > >> have messages
> appended
> > > before
> > > > > it
> > > > > > > was
> > > > > > > > > > upgraded to
> > > > > > > > > > > include
> > > > > > > > > > > > KIP-87.
> > > > > > > > > > > > >> > > >>
> > > > > > > > > > > > >> > > >> Ismael
> > > > > > > > > > > > >> > > >>
> > > > > > > > > > > > >> > > >
> > > > > > > > > > > > >> > > >
> > > > > > > > > > > > >> > > >
> > > > > > > > > > > > >> > > > --
> > > > > > > > > > > > >> > > > -Regards,
> > > > > > > > > > > > >> > > > Mayuresh R. Gharat
> > > > > > > > > > > > >> > > > (862) 250-7125
> > > > > > > > > > > > >> > > >
> > > > > > > > > > > > >> > >
> > > > > > > > > > > > >> > >
> > > > > > > > > > > > >> > >
> > > > > > > > > > > > >> > > --
> > > > > > > > > > > > >> > > -Regards,
> > > > > > > > > > > > >> > > Mayuresh R. Gharat
> > > > > > > > > > > > >> > > (862) 250-7125
> > > > > > > > > > > > >> > >
> > > > > > > > > > > > >> > The information
> contained in
> > > this
> > > > > > email
> > > > > > > is
> > > > > > > > > > strictly
> > > > > > > > > > > > confidential and for
> > > > > > > > > > > > >> > the use of the
> addressee only,
> > > > > unless
> > > > > > > > otherwise
> > > > > > > > > > > indicated. If
> > > > > > > > > > > > you are
> > > > > > > > > > > > >> not
> > > > > > > > > > > > >> > the intended recipient,
> please
> > > do
> > > > > not
> > > > > > > read,
> > > > > > > > > copy,
> > > > > > > > > > use or
> > > > > > > > > > > > disclose to
> > > > > > > > > > > > >> others
> > > > > > > > > > > > >> > this message or any
> > attachment.
> > > > > Please
> > > > > > > also
> > > > > > > > > > notify the
> > > > > > > > > > > sender
> > > > > > > > > > > > by
> > > > > > > > > > > > >> replying
> > > > > > > > > > > > >> > to this email or by
> telephone
> > > > > (+44(020
> > > > > > > 7896
> > > > > > > > > 0011)
> > > > > > > > > > and
> > > > > > > > > > > then
> > > > > > > > > > > > delete the
> > > > > > > > > > > > >> email
> > > > > > > > > > > > >> > and any copies of it.
> > Opinions,
> > > > > > > conclusion
> > > > > > > > (etc)
> > > > > > > > > > that
> > > > > > > > > > > do not
> > > > > > > > > > > > relate to
> > > > > > > > > > > > >> the
> > > > > > > > > > > > >> > official business of
> this
> > > company
> > > > > > shall
> > > > > > > be
> > > > > > > > > > understood as
> > > > > > > > > > > > neither given
> > > > > > > > > > > > >> nor
> > > > > > > > > > > > >> > endorsed by it. IG is a
> > trading
> > > > name
> > > > > > of
> > > > > > > IG
> > > > > > > > > Markets
> > > > > > > > > > > Limited (a
> > > > > > > > > > > > company
> > > > > > > > > > > > >> > registered in England
> and
> > Wales,
> > > > > > company
> > > > > > > > number
> > > > > > > > > > > 04008957) and
> > > > > > > > > > > > IG Index
> > > > > > > > > > > > >> > Limited (a company
> registered
> > in
> > > > > > > England and
> > > > > > > > > > Wales,
> > > > > > > > > > > company
> > > > > > > > > > > > number
> > > > > > > > > > > > >> > 01190902). Registered
> address
> > at
> > > > > > Cannon
> > > > > > > Bridge
> > > > > > > > > > House, 25
> > > > > > > > > > > > Dowgate Hill,
> > > > > > > > > > > > >> > London EC4R 2YA. Both IG
> > Markets
> > > > > > Limited
> > > > > > > > > (register
> > > > > > > > > > > number
> > > > > > > > > > > > 195355) and IG
> > > > > > > > > > > > >> > Index Limited (register
> number
> > > > > 114059)
> > > > > > > are
> > > > > > > > > > authorised
> > > > > > > > > > > and
> > > > > > > > > > > > regulated by
> > > > > > > > > > > > >> the
> > > > > > > > > > > > >> > Financial Conduct
> Authority.
> > > > > > > > > > > > >> >
> > > > > > > > > > > > >>
> > > > > > > > > > > > >>
> > > > > > > > > > > > >>
> > > > > > > > > > > > >> --
> > > > > > > > > > > > >> -Regards,
> > > > > > > > > > > > >> Mayuresh R. Gharat
> > > > > > > > > > > > >> (862) 250-7125
> > > > > > > > > > > > >> The information contained
> in
> > this
> > > > > email
> > > > > > is
> > > > > > > > > strictly
> > > > > > > > > > > > confidential and for
> > > > > > > > > > > > >> the use of the addressee
> only,
> > > > unless
> > > > > > > otherwise
> > > > > > > > > > > indicated. If
> > > > > > > > > > > > you are not
> > > > > > > > > > > > >> the intended recipient,
> please
> > do
> > > > not
> > > > > > > read,
> > > > > > > > copy,
> > > > > > > > > > use or
> > > > > > > > > > > > disclose to others
> > > > > > > > > > > > >> this message or any
> attachment.
> > > > Please
> > > > > > > also
> > > > > > > > notify
> > > > > > > > > > the
> > > > > > > > > > > sender
> > > > > > > > > > > > by replying
> > > > > > > > > > > > >> to this email or by
> telephone
> > > > (+44(020
> > > > > > > 7896
> > > > > > > > 0011)
> > > > > > > > > > and then
> > > > > > > > > > > > delete the email
> > > > > > > > > > > > >> and any copies of it.
> Opinions,
> > > > > > > conclusion (etc)
> > > > > > > > > > that do
> > > > > > > > > > > not
> > > > > > > > > > > > relate to the
> > > > > > > > > > > > >> official business of this
> > company
> > > > > shall
> > > > > > be
> > > > > > > > > > understood as
> > > > > > > > > > > > neither given nor
> > > > > > > > > > > > >> endorsed by it. IG is a
> trading
> > > name
> > > > > of
> > > > > > IG
> > > > > > > > Markets
> > > > > > > > > > > Limited (a
> > > > > > > > > > > > company
> > > > > > > > > > > > >> registered in England and
> Wales,
> > > > > company
> > > > > > > number
> > > > > > > > > > 04008957)
> > > > > > > > > > > and
> > > > > > > > > > > > IG Index
> > > > > > > > > > > > >> Limited (a company
> registered in
> > > > > England
> > > > > > > and
> > > > > > > > > Wales,
> > > > > > > > > > > company
> > > > > > > > > > > > number
> > > > > > > > > > > > >> 01190902). Registered
> address at
> > > > > Cannon
> > > > > > > Bridge
> > > > > > > > > > House, 25
> > > > > > > > > > > > Dowgate Hill,
> > > > > > > > > > > > >> London EC4R 2YA. Both IG
> Markets
> > > > > Limited
> > > > > > > > (register
> > > > > > > > > > number
> > > > > > > > > > > > 195355) and IG
> > > > > > > > > > > > >> Index Limited (register
> number
> > > > 114059)
> > > > > > are
> > > > > > > > > > authorised and
> > > > > > > > > > > > regulated by the
> > > > > > > > > > > > >> Financial Conduct
> Authority.
> > > > > > > > > > > > >>
> > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > > --
> > > > > > > > > > > > > -Regards,
> > > > > > > > > > > > > Mayuresh R. Gharat
> > > > > > > > > > > > > (862) 250-7125
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > --
> > > > > > > > > > > > -Regards,
> > > > > > > > > > > > Mayuresh R. Gharat
> > > > > > > > > > > > (862) 250-7125
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > The information contained in
> this email
> > > is
> > > > > > > strictly
> > > > > > > > > > confidential
> > > > > > > > > > > and
> > > > > > > > > > > > for the use of the addressee only,
> unless
> > > > > otherwise
> > > > > > > > > indicated.
> > > > > > > > > > If
> > > > > > > > > > > you are
> > > > > > > > > > > > not the intended recipient, please
> do not
> > > read,
> > > > > > > copy, use
> > > > > > > > or
> > > > > > > > > > > disclose to
> > > > > > > > > > > > others this message or any
> attachment.
> > Please
> > > > > also
> > > > > > > notify
> > > > > > > > the
> > > > > > > > > > sender
> > > > > > > > > > > by
> > > > > > > > > > > > replying to this email or by
> telephone
> > > (+44(020
> > > > > > 7896
> > > > > > > 0011)
> > > > > > > > > and
> > > > > > > > > > then
> > > > > > > > > > > delete
> > > > > > > > > > > > the email and any copies of it.
> Opinions,
> > > > > > conclusion
> > > > > > > (etc)
> > > > > > > > > > that do
> > > > > > > > > > > not
> > > > > > > > > > > > relate to the official business of
> this
> > > company
> > > > > > > shall be
> > > > > > > > > > understood
> > > > > > > > > > > as
> > > > > > > > > > > > neither given nor endorsed by it. IG
> is a
> > > > trading
> > > > > > > name of
> > > > > > > > IG
> > > > > > > > > > Markets
> > > > > > > > > > > > Limited (a company registered in
> England
> > and
> > > > > Wales,
> > > > > > > company
> > > > > > > > > > number
> > > > > > > > > > > > 04008957) and IG Index Limited (a
> company
> > > > > > registered
> > > > > > > in
> > > > > > > > > > England and
> > > > > > > > > > > Wales,
> > > > > > > > > > > > company number 01190902). Registered
> > address
> > > at
> > > > > > > Cannon
> > > > > > > > Bridge
> > > > > > > > > > House,
> > > > > > > > > > > 25
> > > > > > > > > > > > Dowgate Hill, London EC4R 2YA. Both
> IG
> > > Markets
> > > > > > > Limited
> > > > > > > > > > (register
> > > > > > > > > > > number
> > > > > > > > > > > > 195355) and IG Index Limited
> (register
> > number
> > > > > > > 114059) are
> > > > > > > > > > authorised
> > > > > > > > > > > and
> > > > > > > > > > > > regulated by the Financial Conduct
> > Authority.
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > The information contained in this email is
> > strictly
> > > > > > > confidential
> > > > > > > > > and
> > > > > > > > > > for
> > > > > > > > > > > the use of the addressee only, unless
> otherwise
> > > > > > indicated.
> > > > > > > If you
> > > > > > > > > > are not
> > > > > > > > > > > the intended recipient, please do not
> read, copy,
> > > use
> > > > > or
> > > > > > > disclose
> > > > > > > > > to
> > > > > > > > > > others
> > > > > > > > > > > this message or any attachment. Please also
> > notify
> > > > the
> > > > > > > sender by
> > > > > > > > > > replying
> > > > > > > > > > > to this email or by telephone (+44(020
> 7896 0011
> > > <020%207896%200011>) and
> > > > > > then
> > > > > > > delete
> > > > > > > > > > the email
> > > > > > > > > > > and any copies of it. Opinions, conclusion
> (etc)
> > > that
> > > > > do
> > > > > > > not
> > > > > > > > relate
> > > > > > > > > > to the
> > > > > > > > > > > official business of this company shall be
> > > understood
> > > > > as
> > > > > > > neither
> > > > > > > > > > given nor
> > > > > > > > > > > endorsed by it. IG is a trading name of IG
> > Markets
> > > > > > Limited
> > > > > > > (a
> > > > > > > > > company
> > > > > > > > > > > registered in England and Wales, company
> number
> > > > > 04008957)
> > > > > > > and IG
> > > > > > > > > > Index
> > > > > > > > > > > Limited (a company registered in England
> and
> > Wales,
> > > > > > company
> > > > > > > > number
> > > > > > > > > > > 01190902). Registered address at Cannon
> Bridge
> > > House,
> > > > > 25
> > > > > > > Dowgate
> > > > > > > > > > Hill,
> > > > > > > > > > > London EC4R 2YA. Both IG Markets Limited
> > (register
> > > > > number
> > > > > > > 195355)
> > > > > > > > > > and IG
> > > > > > > > > > > Index Limited (register number 114059) are
> > > authorised
> > > > > and
> > > > > > > > regulated
> > > > > > > > > > by the
> > > > > > > > > > > Financial Conduct Authority.
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > The information contained in this email is
> strictly
> > > > > > confidential
> > > > > > > and
> > > > > > > > for
> > > > > > > > > > the use of the addressee only, unless otherwise
> > > indicated.
> > > > If
> > > > > > > you are
> > > > > > > > not
> > > > > > > > > > the intended recipient, please do not read,
> copy, use
> > or
> > > > > > > disclose to
> > > > > > > > > others
> > > > > > > > > > this message or any attachment. Please also
> notify the
> > > > sender
> > > > > > by
> > > > > > > > replying
> > > > > > > > > > to this email or by telephone (+44(020 7896 0011
> > > <020%207896%200011>) and then
> > > > > > > delete the
> > > > > > > > > email
> > > > > > > > > > and any copies of it. Opinions, conclusion (etc)
> that
> > do
> > > > not
> > > > > > > relate to
> > > > > > > > > the
> > > > > > > > > > official business of this company shall be
> understood
> > as
> > > > > > neither
> > > > > > > given
> > > > > > > > > nor
> > > > > > > > > > endorsed by it. IG is a trading name of IG
> Markets
> > > Limited
> > > > (a
> > > > > > > company
> > > > > > > > > > registered in England and Wales, company number
> > 04008957)
> > > > and
> > > > > > IG
> > > > > > > Index
> > > > > > > > > > Limited (a company registered in England and
> Wales,
> > > company
> > > > > > > number
> > > > > > > > > > 01190902). Registered address at Cannon Bridge
> House,
> > 25
> > > > > > Dowgate
> > > > > > > Hill,
> > > > > > > > > > London EC4R 2YA. Both IG Markets Limited
> (register
> > number
> > > > > > > 195355) and
> > > > > > > > IG
> > > > > > > > > > Index Limited (register number 114059) are
> authorised
> > and
> > > > > > > regulated by
> > > > > > > > > the
> > > > > > > > > > Financial Conduct Authority.
> > > > > > > > > >
> > > > > > > > > The information contained in this email is strictly
> > > > > confidential
> > > > > > > and for
> > > > > > > > > the use of the addressee only, unless otherwise
> > indicated.
> > > If
> > > > > you
> > > > > > > are not
> > > > > > > > > the intended recipient, please do not read, copy,
> use or
> > > > > disclose
> > > > > > > to
> > > > > > > > others
> > > > > > > > > this message or any attachment. Please also notify
> the
> > > sender
> > > > > by
> > > > > > > replying
> > > > > > > > > to this email or by telephone (+44(020 7896 0011
> > > <020%207896%200011>) and then
> > > > > delete
> > > > > > > the
> > > > > > > > email
> > > > > > > > > and any copies of it. Opinions, conclusion (etc)
> that do
> > > not
> > > > > > > relate to
> > > > > > > > the
> > > > > > > > > official business of this company shall be
> understood as
> > > > > neither
> > > > > > > given
> > > > > > > > nor
> > > > > > > > > endorsed by it. IG is a trading name of IG Markets
> > Limited
> > > (a
> > > > > > > company
> > > > > > > > > registered in England and Wales, company number
> 04008957)
> > > and
> > > > > IG
> > > > > > > Index
> > > > > > > > > Limited (a company registered in England and Wales,
> > company
> > > > > > number
> > > > > > > > > 01190902). Registered address at Cannon Bridge
> House, 25
> > > > > Dowgate
> > > > > > > Hill,
> > > > > > > > > London EC4R 2YA. Both IG Markets Limited (register
> number
> > > > > 195355)
> > > > > > > and IG
> > > > > > > > > Index Limited (register number 114059) are
> authorised and
> > > > > > > regulated by
> > > > > > > > the
> > > > > > > > > Financial Conduct Authority.
> > > > > > > > >
> > > > > > > > >
> > > > > > > > The information contained in this email is strictly
> > > > confidential
> > > > > > and
> > > > > > > for
> > > > > > > > the use of the addressee only, unless otherwise
> indicated.
> > If
> > > > you
> > > > > > > are not
> > > > > > > > the intended recipient, please do not read, copy,
> use or
> > > > disclose
> > > > > > to
> > > > > > > others
> > > > > > > > this message or any attachment. Please also notify
> the
> > sender
> > > > by
> > > > > > > replying
> > > > > > > > to this email or by telephone (+44(020 7896 0011
> > > <020%207896%200011>) and then
> > > > delete
> > > > > > > the email
> > > > > > > > and any copies of it. Opinions, conclusion (etc)
> that do
> > not
> > > > > relate
> > > > > > > to the
> > > > > > > > official business of this company shall be
> understood as
> > > > neither
> > > > > > > given nor
> > > > > > > > endorsed by it. IG is a trading name of IG Markets
> Limited
> > (a
> > > > > > company
> > > > > > > > registered in England and Wales, company number
> 04008957)
> > and
> > > > IG
> > > > > > > Index
> > > > > > > > Limited (a company registered in England and Wales,
> company
> > > > > number
> > > > > > > > 01190902). Registered address at Cannon Bridge
> House, 25
> > > > Dowgate
> > > > > > > Hill,
> > > > > > > > London EC4R 2YA. Both IG Markets Limited (register
> number
> > > > 195355)
> > > > > > > and IG
> > > > > > > > Index Limited (register number 114059) are
> authorised and
> > > > > regulated
> > > > > > > by the
> > > > > > > > Financial Conduct Authority.
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > The information contained in this email is strictly
> confidential
> > > and
> > > > > for
> > > > > > > the use of the addressee only, unless otherwise indicated.
> If you
> > > are
> > > > > not
> > > > > > > the intended recipient, please do not read, copy, use or
> disclose
> > > to
> > > > > > others
> > > > > > > this message or any attachment. Please also notify the
> sender by
> > > > > replying
> > > > > > > to this email or by telephone (+44(020 7896 0011
> > > <020%207896%200011>) and then delete the
> > > > > > email
> > > > > > > and any copies of it. Opinions, conclusion (etc) that do
> not
> > relate
> > > > to
> > > > > > the
> > > > > > > official business of this company shall be understood as
> neither
> > > > given
> > > > > > nor
> > > > > > > endorsed by it. IG is a trading name of IG Markets Limited
> (a
> > > company
> > > > > > > registered in England and Wales, company number 04008957)
> and IG
> > > > Index
> > > > > > > Limited (a company registered in England and Wales, company
> > number
> > > > > > > 01190902). Registered address at Cannon Bridge House, 25
> Dowgate
> > > > Hill,
> > > > > > > London EC4R 2YA. Both IG Markets Limited (register number
> 195355)
> > > and
> > > > > IG
> > > > > > > Index Limited (register number 114059) are authorised and
> > regulated
> > > > by
> > > > > > the
> > > > > > > Financial Conduct Authority.
> > > > > > >
> > > > > > The information contained in this email is strictly
> confidential
> > and
> > > > for
> > > > > > the use of the addressee only, unless otherwise indicated.
> If you
> > are
> > > > not
> > > > > > the intended recipient, please do not read, copy, use or
> disclose
> > to
> > > > > others
> > > > > > this message or any attachment. Please also notify the
> sender by
> > > > replying
> > > > > > to this email or by telephone (+44(020 7896 0011
> > <020%207896%200011>)
> > > and then delete the
> > > > > email
> > > > > > and any copies of it. Opinions, conclusion (etc) that do not
> relate
> > > to
> > > > > the
> > > > > > official business of this company shall be understood as
> neither
> > > given
> > > > > nor
> > > > > > endorsed by it. IG is a trading name of IG Markets Limited (a
> > company
> > > > > > registered in England and Wales, company number 04008957)
> and IG
> > > Index
> > > > > > Limited (a company registered in England and Wales, company
> number
> > > > > > 01190902). Registered address at Cannon Bridge House, 25
> Dowgate
> > > Hill,
> > > > > > London EC4R 2YA. Both IG Markets Limited (register number
> 195355)
> > and
> > > > IG
> > > > > > Index Limited (register number 114059) are authorised and
> regulated
> > > by
> > > > > the
> > > > > > Financial Conduct Authority.
> > > > > >
> > > > > The information contained in this email is strictly
> confidential and
> > > for
> > > > > the use of the addressee only, unless otherwise indicated. If
> you are
> > > not
> > > > > the intended recipient, please do not read, copy, use or
> disclose to
> > > > others
> > > > > this message or any attachment. Please also notify the sender
> by
> > > replying
> > > > > to this email or by telephone (+44(020 7896 0011
> <020%207896%200011>)
> > > and then delete the
> > > > email
> > > > > and any copies of it. Opinions, conclusion (etc) that do not
> relate
> > to
> > > > the
> > > > > official business of this company shall be understood as
> neither
> > given
> > > > nor
> > > > > endorsed by it. IG is a trading name of IG Markets Limited (a
> company
> > > > > registered in England and Wales, company number 04008957) and
> IG
> > Index
> > > > > Limited (a company registered in England and Wales, company
> number
> > > > > 01190902). Registered address at Cannon Bridge House, 25
> Dowgate
> > Hill,
> > > > > London EC4R 2YA. Both IG Markets Limited (register number
> 195355) and
> > > IG
> > > > > Index Limited (register number 114059) are authorised and
> regulated
> > by
> > > > the
> > > > > Financial Conduct Authority.
> > > > >
> > > > The information contained in this email is strictly confidential
> and
> > for
> > > > the use of the addressee only, unless otherwise indicated. If
> you are
> > not
> > > > the intended recipient, please do not read, copy, use or
> disclose to
> > > others
> > > > this message or any attachment. Please also notify the sender by
> > replying
> > > > to this email or by telephone (+44(020 7896 0011
> <020%207896%200011>)
> > > and then delete the email
> > > > and any copies of it. Opinions, conclusion (etc) that do not
> relate to
> > > the
> > > > official business of this company shall be understood as neither
> given
> > > nor
> > > > endorsed by it. IG is a trading name of IG Markets Limited (a
> company
> > > > registered in England and Wales, company number 04008957) and IG
> Index
> > > > Limited (a company registered in England and Wales, company
> number
> > > > 01190902). Registered address at Cannon Bridge House, 25 Dowgate
> Hill,
> > > > London EC4R 2YA. Both IG Markets Limited (register number
> 195355) and
> > IG
> > > > Index Limited (register number 114059) are authorised and
> regulated by
> > > the
> > > > Financial Conduct Authority.
> > > >
> > >
> > The information contained in this email is strictly confidential and
> for
> > the use of the addressee only, unless otherwise indicated. If you
> are not
> > the intended recipient, please do not read, copy, use or disclose to
> others
> > this message or any attachment. Please also notify the sender by
> replying
> > to this email or by telephone (+44(020 7896 0011) and then delete
> the email
> > and any copies of it. Opinions, conclusion (etc) that do not relate
> to the
> > official business of this company shall be understood as neither
> given nor
> > endorsed by it. IG is a trading name of IG Markets Limited (a company
> > registered in England and Wales, company number 04008957) and IG
> Index
> > Limited (a company registered in England and Wales, company number
> > 01190902). Registered address at Cannon Bridge House, 25 Dowgate
> Hill,
> > London EC4R 2YA. Both IG Markets Limited (register number 195355)
> and IG
> > Index Limited (register number 114059) are authorised and regulated
> by the
> > Financial Conduct Authority.
> >
>
>
> The information contained in this email is strictly confidential and for
> the use of the addressee only, unless otherwise indicated. If you are not
> the intended recipient, please do not read, copy, use or disclose to others
> this message or any attachment. Please also notify the sender by replying
> to this email or by telephone (+44(020 7896 0011) and then delete the email
> and any copies of it. Opinions, conclusion (etc) that do not relate to the
> official business of this company shall be understood as neither given nor
> endorsed by it. IG is a trading name of IG Markets Limited (a company
> registered in England and Wales, company number 04008957) and IG Index
> Limited (a company registered in England and Wales, company number
> 01190902). Registered address at Cannon Bridge House, 25 Dowgate Hill,
> London EC4R 2YA. Both IG Markets Limited (register number 195355) and IG
> Index Limited (register number 114059) are authorised and regulated by the
> Financial Conduct Authority.
>
