querying them would be inefficient (impossible?
Impossible. In the case of multi-column partition key all of them must be
restricted in WHERE clause:
CREATE TABLE data.table (id1 int, id2 int, primary KEY ((id1,id2)));
SELECT * FROM data.table WHERE id1 = 0;
InvalidRequest: Error from server:
No the employees would end up in arbitrary partitions, and querying them would
be inefficient (impossible? - I am levels back on C* so don’t know if ALLOW
FILTERING even works for this).
I would be tempted to use organization_id only or organization_Id and maybe a
few shard bits (if you are
Yes, look at this example. But you need to add 'fake' partition with the same
value for all rows, that will cause them to be stored on the same nodes.
Best regards, Vladimir Yudovin,
Winguzone - Hosted Cloud Cassandra on Azure and SoftLayer.
Launch your cluster in minutes.
On Sat, 08
In the case of PRIMARY KEY((organization_id, employee_id)), could I still
do a query like Select ... where organization_id = x, to get all employees
in a particular organization?
And, this will put all those employees in the same node, right?
On Sun, Oct 9, 2016 at 9:17 AM, Graham Sanderson
Nomenclature is tricky, but PRIMARY KEY((organization_id, employee_id)) will
make organization_id, employee_id the partition key which equates roughly to
your latter sentence (I’m not sure about the 4 billion limit - that may be the
new actual limit, but probably not a good idea).
> On Oct 8,
I was using the term “touch” loosely to hopefully mean pre-fetch, though I
suspect (I think intel has been de-emphasizing) you can still do a sensible
prefetch instruction in native code. Even if not you are still better blocking
in JNI code - I haven’t looked at the link to see if the correct
Hi,
This is starting to get into dev list territory.
Interesting idea to touch every 4K page you are going to read.
You could use this to minimize the cost.
http://stackoverflow.com/questions/36298111/is-it-possible-to-use-sun-misc-unsafe-to-call-c-functions-without-jni/36309652#36309652
Maybe
the last '4 billion rows' should say '4 billion columns / cells'
On Sun, Oct 9, 2016 at 6:34 AM, Ali Akhtar wrote:
> Say I have the following primary key:
> PRIMARY KEY((organization_id, employee_id))
>
> Will this create 1 row whose primary key is the organization id, but
Say I have the following primary key:
PRIMARY KEY((organization_id, employee_id))
Will this create 1 row whose primary key is the organization id, but it has
a 4 billion column / cell limit?
Or will this create 1 row for each employee in the same organization, so if
i have 5 employees, they will
I haven’t studied the read path that carefully, but there might be a spot at
the C* level rather than JVM level where you could effectively do a JNI touch
of the mmap region you’re going to need next.
> On Oct 8, 2016, at 7:17 PM, Graham Sanderson wrote:
>
> We don’t use
We don’t use Azul’s Zing, but it does have the nice feature that all threads
don’t have to reach safepoints at the same time. That said we make heavy use of
Cassandra (with off heap memtables - not directly related but allows us a lot
more GC headroom) and SOLR where we switched to mmap because
Is it possible to have multiple clustering keys in cassandra, or some other
way to order by multiple columns?
For example, say I have a table of songs, and each song has a rating and a
date.
I want to sort songs by rating first, and then with newer songs on top.
So if two songs have 5 rating,
Hi Vladamir,
Thanks for the response. I assume then that it is safe to remove the
directories that are not current as per the system_schema.tables table. I have
dozens of the same table and haven't dropped and added nearly that many times.
Do any of the nodetool or other commands clean up these
Linux automatically uses free memory as cache. It's not swap.
http://www.tldp.org/LDP/lki/lki-4.html
On Sat, Oct 8, 2016 at 11:12 AM Vladimir Yudovin
wrote:
> Sorry, I don't catch something. What page (memory) cache can exist if
> there is no swap file.
> Where are those
Hi,
Nope I mean page cache. Linux doesn't call the cache it maintains using
free memory a file cache. It uses free (and some of the time not so
free!) memory to buffer writes and to cache recently written/read data.
http://www.tldp.org/LDP/lki/lki-4.html
When Linux decides it needs free memory
Each table has unique id (suffix). If you drop and then recreate table with the
same name it gets new id.
Try
SELECT keyspace_name, table_name, id FROM system_schema.tables ;
to determinate actual ID.
You can limit request to specific keyspace or table.
Best regards, Vladimir Yudovin,
Page cache is data pending flush to disk and data cached from disk.
Do you mean file cache?
Best regards, Vladimir Yudovin,
Winguzone - Hosted Cloud Cassandra on Azure and SoftLayer.
Launch your cluster in minutes.
On Sat, 08 Oct 2016 13:40:19 -0400 Ariel Weisberg
ar...@weisberg.ws
Hello,
I am using Cassandra 3.0.9 and I have encountered an issue where the nodes in
my 3 node cluster have vastly different amounts of data even though they should
be roughly the same. When I looked through the data directory for my database
on two of the nodes, I see a number of directories
Hi,
Page cache is in use even if you disable swap. Swap is anonymous memory,
and whatever else the Linux kernel supports paging out. Page cache is
data pending flush to disk and data cached from disk.
Given how bad the GC pauses are in C* I think it's not the high pole in
the tent. Until key
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