Why is Quorum not sufficient for Linearization?
Cassandra in general can't provide guarantee any ordering of the executed queries, since nodes may fail or rejoin the in arbitrary points in time. But why can't it provide ordering for queries run at at least the quorum level? Given that none of the updates get lost, why would order still an issue? Can you maybe illustrate a scenario which shows how/where the order would get lost if writes and reads always occurred with quorum consistency?
Semantics of Triggers ( their future)
Information on triggers seems a bit scarce so far. The blog entry on http://www.datastax.com/dev/blog/whats-new-in-cassandra-2-0-prototype-triggers-support mentions them as being usable for maintaining materialized views, since they'll be handled similarly to logged/atomic batches - is that enough to ensure that values in materialized views remain accurate? Or does atomic in this context really mean atomic, isolated and linearized per node - much like updates of indexed columns are handled too? (indexed here being secondary indices.) Also, the document mentions triggers being partition-level. Does this mean trigger code (or rather the generated mutations of a trigger) cannot manipulate more than one partition (and thus also cannot manipulate more than one columnfamily)? How can materialized views be maintained without being able to write to 2 columnfamilies (the cf with the actual values, and the cf with the pre-aggregated ones)? Finally, one more question about the future of triggers: Since it is planned for 3.0 to have user defined functions (UDFs) in some PL/SQL-like language, will it (eventually) be possible to write triggers in this language too? Or will triggers always have to be directly loaded into the JVM processes of the Cassandra instances? It would be great if there was some way to be able to load trigger code from the client-side without having to manipulate the code and/or libraries on the server-side for scenarios where Cassandra is being used as a hosted service (PaaS). I realize that triggers are still experimental, but this looks like an exciting new feature.
Not-Equals (!=) in Where Clause
Looking through the CQL 3.1 grammar for Cassandra 2.1, I noticed that the not-equals operator (!=) is in the grammar definition, but I can't seem to find any legal way to use it. Is != supported as part of the where clause in Cassandra? Or is it the grammar for some other purpose?
Named Parameters in Prepared Statement
Looking through the CQL 3.1 grammar in Cassandra, I found a ':' ident alternative in the value rule (line 961). Is this for binding named parameters in prepared statements? Is this currently supported by any of the drivers or in Cassandra (2.1) itself? Looking at the docs and the current Java driver it doesn't seem that way.
Cassandra Java Client
Hi, is the DataStax Java Driver for Apache Cassandra ( https://github.com/datastax/java-driver) the official/recommended Java Client to use for accessing Cassandra from Java? Does Cassandra itself (i.e. the apache-cassandra-* jars) not contain any CQL clients? Thanks!
Cassandra Version History
Hi, is there a history/list showing which major (as in x.y) versions of Cassandra were released on which date? Or is the list on Wikipedia complete? Did 2.0 come after 1.2? Thanks!
Cassandra 2.0.5 Configuration
Hi, when building and running Cassandra 2.0.5 from the git repository, the log is full of lines like these 00:01:42.286 [CompactionExecutor:1] DEBUG o.a.c.d.compaction.CompactionManager - Checking system.local When building and running 2.1.0/trunk the log settings are however fine. Is there any way I can lower the log setting in 2.0.5? I already tried setting log4j.rootLogger=ERROR,stdout,R it in conf/log4j-server.properties, but that did not seem to have any effect. Thanks!
Re: Looking for a good Ruby client
@Mat Brown: (while still retaining compatibility with CQL2 structures). Do you mean by exceeding what Cassandra itself provides in terms of CQL2/3 interoperability? I'm looking into something similar currently (however in Java not in Ruby) and would be interested in your experiences, if you follow through with the plan. Do you have a blog? Thanks! 2012/11/20 Alain RODRIGUEZ arodr...@gmail.com @Mat Well I guess you could add your Ruby client to this list since there is not a lot of them yet. http://wiki.apache.org/cassandra/ClientOptions Alain 2012/11/20 Mat Brown m...@brewster.com As the author of Cequel, I can assure you it is excellent ; ) We use it in production at Brewster and it is quite stable. If you try it out and find any bugs, we'll fix 'em quickly. I'm planning a big overhaul of the model layer over the holidays to expose all the new data modeling goodness in CQL3 (while still retaining compatibility with CQL2 structures). On Thu, Nov 15, 2012 at 3:42 PM, Harry Wilkinson hwilkin...@mdsol.com wrote: Update on this: someone just pointed me towards the Cequel gem: https://github.com/brewster/cequel The way it's described in the readme it looks like exactly what I was looking for - a modern, CQL-based gem that is in active development and also follows the ActiveModel pattern. I'd be very interested to hear if anybody has used this, whether it's stable/reliable, etc. Thanks. Harry On 2 August 2012 00:31, Thorsten von Eicken t...@rightscale.com wrote: Harry, we're in a similar situation and are starting to work out our own ruby client. The biggest issue is that it doesn't make much sense to build a higher level abstraction on anything other than CQL3, given where things are headed. At least this is our opinion. At the same time, CQL3 is just barely becoming usable and still seems rather deficient in wide-row usage. The tricky part is that with the current CQL3 you have to construct quite complex iterators to retrieve a large result set. Which means that you end up having to either parse CQL3 coming in to insert the iteration stuff, or you have to pass CQL3 fragments in and compose them together with iterator clauses. Not fun stuff either way. The only good solution I see is to switch to a streaming protocol (or build some form of continue on top of thrift) such that the client can ask for a huge result set and the cassandra coordinator can break it into sub-queries as it sees fit and return results chunk-by-chunk. If this is really the path forward then all abstractions built above CQL3 before that will either have a good piece of complex code that can be deleted or worse, will have an interface that is no longer best practice. Good luck! Thorsten On 8/1/2012 1:47 PM, Harry Wilkinson wrote: Hi, I'm looking for a Ruby client for Cassandra that is pretty high-level. I am really hoping to find a Ruby gem of high quality that allows a developer to create models like you would with ActiveModel. So far I have figured out that the canonical Ruby client for Cassandra is Twitter's Cassandra gem of the same name. It looks great - mature, still in active development, etc. No stated support for Ruby 1.9.3 that I can see, but I can probably live with that for now. What I'm looking for is a higher-level gem built on that gem that works like ActiveModel in that you just include a module in your model class and that gives you methods to declare your model's serialized attributes and also the usual ActiveModel methods like 'save!', 'valid?', 'find', etc. I've been trying out some different NoSQL databases recently, and for example there is an official Ruby client for Riak with a domain model that is close to Riak's, but then there's also a gem called 'Ripple' that uses a domain model that is closer to what most Ruby developers are used to. So it looks like Twitter's Cassandra gem is the one that stays close to the domain model of Cassandra, and what I'm looking for is a gem that's a Cassandra equivalent of RIpple. From some searching I found cassandra_object, which has been inactive for a couple of years, but there's a fork that looks like it's being maintained, but I have not found any kind of information to suggest the maintained fork is in general use yet. I have found quite a lot of gems of a similar style that people have started and then not really got very far with. So, does anybody know of a suitable gem? Would you recommend it? Or perhaps you would recommend not using such a gem and sticking with the lower-level client gem? Thanks in advance for your advice. Harry
Re: Looking for a good Ruby client
Thanks Mat! I thought you were going to expose the internals of CQL3 features like (wide rows with) complex keys and collections to CQL2 clients (which is something that should generally be possible, if Datastax' blog posts are accurate, i.e. an actual description of how things were implemented and not just a conceptual one). I'm still negotiating with my project lead on what features will ultimately be implemented, so I'm not sure whether CQL2/3 interoperability will actually make it into the final 'product' .. but it isn't very high up on the priority list, so it will most likely be implemented towards the end, and thus I guess it'll also kind of depend on how much CQL2 support will be provided by Cassandra itself when the time comes. 2012/11/20 Mat Brown m...@brewster.com Hi Timmy, I haven't done a lot of playing with CQL3 yet, mostly just reading the blog posts, so the following is subject to change : ) Right now, the Cequel model layer has a skinny row model (which is designed to follow common patterns of Ruby ORMs) and a wide row model (which is designed to behave more or less like a Hash, the equivalent of Java's HashMap). The two don't integrate with each other in any meaningful way, but as far as I understand it, they do pretty much cover the data modeling possibilities in CQL2. The big idea I've got for the overhaul of Cequel for CQL3 is to allow building a rich, nested data model by integrating different flavors of CQL3 table, most notably multi-column primary keys, as well as collections. The core data types I have in mind are: 1) Skinny row with simple primary key (e.g. blogs, with blog_id key) 2) Skinny row with complex primary key (e.g. blog_posts, with (blog_id, post_id) key) 3) Wide row with simple primary key (e.g. blog_languages -- kind of a weak example but i can't think of anything better for a blog : ) 4) Wide row with complex primary key (e.g. blog_post_tags) My goal is to make it easy to model one-one relationships via a shared primary key, and one-many via a shared prefix of the primary key. So, for instance, blogs and blog_languages rows would be one-one (both with a blog_id primary key) and blogs and blog_posts would be one-many (sharing the blog_id prefix in the primary key). From what I've read, it seems fairly clear that the actual CQL used to interact with #1 will be the same for CQL2 column families and CQL3 tables, so no explicit backward compatibility would be needed. #2 and #4 are, of course, CQL3-only, so backward compatibility isn't an issue there either. What I'm not entirely clear on is #3 -- this is straightforward in CQL2, and presumably a CQL3 table with compact storage would behave in the same way. However, my understanding so far is that a non-compact CQL3 table would treat this structure differently, in that both the key and value of the map would correspond to columns in a CQL3 table. It may make more sense to just target compact storage tables with this data structure, but I'm going to need to play around with it more to figure that out. Otherwise, Cequel will need to provide two flavors of that structure. There's also some tension between CQL3 collections and just using traditional wide-row structures to achieve the same thing. For instance, blog_tags could also just be a tags collection in the blogs table. My plan at this point is to offer both options, since each has its advantages (collections don't require the creation of a separate table; but a separate table gives you access to slices of the collection). Anyway, that's probably a lot more of an answer than you needed, but hopefully the context helps. Definitely interested to hear about the direction you take your client in as well. Finally, regarding a blog, we've got one set up, but it's not live yet. I'll ping you with a link when it is; I'll certainly be posting on the development of the next Cequel release. Cheers, Mat On Tue, Nov 20, 2012 at 9:23 AM, Timmy Turner timm.t...@gmail.com wrote: @Mat Brown: (while still retaining compatibility with CQL2 structures). Do you mean by exceeding what Cassandra itself provides in terms of CQL2/3 interoperability? I'm looking into something similar currently (however in Java not in Ruby) and would be interested in your experiences, if you follow through with the plan. Do you have a blog? Thanks! 2012/11/20 Alain RODRIGUEZ arodr...@gmail.com @Mat Well I guess you could add your Ruby client to this list since there is not a lot of them yet. http://wiki.apache.org/cassandra/ClientOptions Alain 2012/11/20 Mat Brown m...@brewster.com As the author of Cequel, I can assure you it is excellent ; ) We use it in production at Brewster and it is quite stable. If you try it out and find any bugs, we'll fix 'em quickly. I'm planning a big overhaul of the model layer over the holidays to expose all the new data modeling goodness
Re: Datatype Conversion in CQL-Client?
What I meant was the method that the Cassandra-jars give you when you include them in your project: TTransport tr = new TFramedTransport(new TSocket(localhost, 9160)); TProtocol proto = new TBinaryProtocol(tr); Cassandra.Client client = new Cassandra.Client(proto); tr.open(); client.execute_cql_query(ByteBuffer.wrap(cql.getBytes()), Compression.NONE); 2012/11/19 Brian O'Neill b...@alumni.brown.edu I don't think Michael and/or Jonathan have published the CQL java driver yet. (CCing them) Hopefully they'll find a public home for it soon, I hope to include it in the Webinar in December. (http://www.datastax.com/resources/webinars/collegecredit) -brian --- Brian O'Neill Lead Architect, Software Development *Health Market Science* *The Science of Better Results* 2700 Horizon Drive • King of Prussia, PA • 19406 M: 215.588.6024 • @boneill42 http://www.twitter.com/boneill42 • healthmarketscience.com This information transmitted in this email message is for the intended recipient only and may contain confidential and/or privileged material. If you received this email in error and are not the intended recipient, or the person responsible to deliver it to the intended recipient, please contact the sender at the email above and delete this email and any attachments and destroy any copies thereof. Any review, retransmission, dissemination, copying or other use of, or taking any action in reliance upon, this information by persons or entities other than the intended recipient is strictly prohibited. ** ** From: Tommi Laukkanen tlaukka...@gmail.com Reply-To: user@cassandra.apache.org Date: Monday, November 19, 2012 2:36 AM To: user@cassandra.apache.org Subject: Re: Datatype Conversion in CQL-Client? I think Timmy might be referring to the upcoming native CQL Java driver that might be coming with 1.2 - It was mentioned here: http://www.datastax.com/wp-content/uploads/2012/08/7_Datastax_Upcoming_Changes_in_Drivers.pdf I would also be interested on testing that but I can't find it from repositories. Any hints? Regards, Tommi L. *From:* Brian O'Neill [mailto:boneil...@gmail.com] *On Behalf Of *Brian O'Neill *Sent:* 18. marraskuuta 2012 17:47 *To:* user@cassandra.apache.org *Subject:* Re: Datatype Conversion in CQL-Client? *Importance:* Low ** ** ** ** If you are talking about the CQL-client that comes with Cassandra (cqlsh), it is actually written in Python: https://github.com/apache/cassandra/blob/trunk/bin/cqlsh ** ** For information on datatypes (and conversion) take a look at the CQL definition: http://www.datastax.com/docs/1.0/references/cql/index (Look at the CQL Data Types section) ** ** If that's not the client you are referencing, let us know which one you mean: http://brianoneill.blogspot.com/2012/08/cassandra-apis-laundry-list.html* *** ** ** -brian ** ** On Nov 17, 2012, at 9:54 PM, Timmy Turner wrote: Thanks for the links, however I'm interested in the functionality that the official Cassandra client/API (which is in Java) offers. ** ** 2012/11/17 aaron morton aa...@thelastpickle.com Does the official/built-in Cassandra CQL client (in 1.2) What language ? ** ** Check the Java http://code.google.com/a/apache-extras.org/p/cassandra-jdbc/ and python http://code.google.com/a/apache-extras.org/p/cassandra-dbapi2/ drivers.** ** ** ** Cheers ** ** ** ** - Aaron Morton Freelance Cassandra Developer New Zealand ** ** @aaronmorton http://www.thelastpickle.com ** ** On 16/11/2012, at 11:21 AM, Timmy Turner timm.t...@gmail.com wrote: Does the official/built-in Cassandra CQL client (in 1.2) offer any built-in option to get direct values/objects when reading a field, instead of just a byte array? ** ** ** ** ** ** -- Brian ONeill Lead Architect, Health Market Science (http://healthmarketscience.com) mobile:215.588.6024 blog: http://weblogs.java.net/blog/boneill42/ blog: http://brianoneill.blogspot.com/ ** **
Re: Datatype Conversion in CQL-Client?
Do these other clients use the thrift API internaly? 2012/11/19 John Sanda john.sa...@gmail.com You might want to take look a org.apache.cassandra.transport.SimpleClient and org.apache.cassandra.transport.messages.ResultMessage. On Mon, Nov 19, 2012 at 9:48 AM, Timmy Turner timm.t...@gmail.com wrote: What I meant was the method that the Cassandra-jars give you when you include them in your project: TTransport tr = new TFramedTransport(new TSocket(localhost, 9160)); TProtocol proto = new TBinaryProtocol(tr); Cassandra.Client client = new Cassandra.Client(proto); tr.open(); client.execute_cql_query(ByteBuffer.wrap(cql.getBytes()), Compression.NONE); 2012/11/19 Brian O'Neill b...@alumni.brown.edu I don't think Michael and/or Jonathan have published the CQL java driver yet. (CCing them) Hopefully they'll find a public home for it soon, I hope to include it in the Webinar in December. (http://www.datastax.com/resources/webinars/collegecredit) -brian --- Brian O'Neill Lead Architect, Software Development *Health Market Science* *The Science of Better Results* 2700 Horizon Drive • King of Prussia, PA • 19406 M: 215.588.6024 • @boneill42 http://www.twitter.com/boneill42 • healthmarketscience.com This information transmitted in this email message is for the intended recipient only and may contain confidential and/or privileged material. If you received this email in error and are not the intended recipient, or the person responsible to deliver it to the intended recipient, please contact the sender at the email above and delete this email and any attachments and destroy any copies thereof. Any review, retransmission, dissemination, copying or other use of, or taking any action in reliance upon, this information by persons or entities other than the intended recipient is strictly prohibited. ** ** From: Tommi Laukkanen tlaukka...@gmail.com Reply-To: user@cassandra.apache.org Date: Monday, November 19, 2012 2:36 AM To: user@cassandra.apache.org Subject: Re: Datatype Conversion in CQL-Client? I think Timmy might be referring to the upcoming native CQL Java driver that might be coming with 1.2 - It was mentioned here: http://www.datastax.com/wp-content/uploads/2012/08/7_Datastax_Upcoming_Changes_in_Drivers.pdf I would also be interested on testing that but I can't find it from repositories. Any hints? Regards, Tommi L. *From:* Brian O'Neill [mailto:boneil...@gmail.com] *On Behalf Of *Brian O'Neill *Sent:* 18. marraskuuta 2012 17:47 *To:* user@cassandra.apache.org *Subject:* Re: Datatype Conversion in CQL-Client? *Importance:* Low ** ** ** ** If you are talking about the CQL-client that comes with Cassandra (cqlsh), it is actually written in Python: https://github.com/apache/cassandra/blob/trunk/bin/cqlsh ** ** For information on datatypes (and conversion) take a look at the CQL definition: http://www.datastax.com/docs/1.0/references/cql/index (Look at the CQL Data Types section) ** ** If that's not the client you are referencing, let us know which one you mean: http://brianoneill.blogspot.com/2012/08/cassandra-apis-laundry-list.html ** ** -brian ** ** On Nov 17, 2012, at 9:54 PM, Timmy Turner wrote: Thanks for the links, however I'm interested in the functionality that the official Cassandra client/API (which is in Java) offers. ** ** 2012/11/17 aaron morton aa...@thelastpickle.com Does the official/built-in Cassandra CQL client (in 1.2) What language ? ** ** Check the Java http://code.google.com/a/apache-extras.org/p/cassandra-jdbc/ and python http://code.google.com/a/apache-extras.org/p/cassandra-dbapi2/ drivers. ** ** Cheers ** ** ** ** - Aaron Morton Freelance Cassandra Developer New Zealand ** ** @aaronmorton http://www.thelastpickle.com ** ** On 16/11/2012, at 11:21 AM, Timmy Turner timm.t...@gmail.com wrote:** ** Does the official/built-in Cassandra CQL client (in 1.2) offer any built-in option to get direct values/objects when reading a field, instead of just a byte array? ** ** ** ** ** ** -- Brian ONeill Lead Architect, Health Market Science (http://healthmarketscience.com) mobile:215.588.6024 blog: http://weblogs.java.net/blog/boneill42/ blog: http://brianoneill.blogspot.com/ ** ** -- - John
Re: Datastax Java Driver
Why is this being released as a separate project, instead of being bundled up with Cassandra? Is it not a part of Cassandra? 2012/11/19 John Sanda john.sa...@gmail.com Fantastic! As for the object mapping API, has there been any discussion/consideration of http://www.hibernate.org/subprojects/ogm.html? On Mon, Nov 19, 2012 at 1:50 PM, Sylvain Lebresne sylv...@datastax.comwrote: Everyone, We've just open-sourced a new Java driver we have been working on here at DataStax. This driver is CQL3 only and is built to use the new binary protocol that will be introduced with Cassandra 1.2. It will thus only work with Cassandra 1.2 onwards. Currently, it means that testing it requires 1.2.0-beta2. This is also alpha software at this point. You are welcome to try and play with it and we would very much welcome feedback, but be sure that break, it will. The driver is accessible at: http://github.com/datastax/java-driver Today we're open-sourcing the core part of this driver. This main goal of this core module is to handle connections to the Cassandra cluster with all the features that one would expect. The currently supported features are: - Asynchronous: the driver uses the new CQL binary protocol asynchronous capabilities. - Nodes discovery. - Configurable load balancing/routing. - Transparent fail-over. - C* tracing handling. - Convenient schema access. - Configurable retry policy. This core module provides a simple low-level API (that works directly with query strings). We plan to release a higher-level, thin object mapping API based on top of this core shortly. Please refer to the project README for more information. -- The DataStax Team -- - John
Re: Datatype Conversion in CQL-Client?
Thanks for the links, however I'm interested in the functionality that the official Cassandra client/API (which is in Java) offers. 2012/11/17 aaron morton aa...@thelastpickle.com Does the official/built-in Cassandra CQL client (in 1.2) What language ? Check the Java http://code.google.com/a/apache-extras.org/p/cassandra-jdbc/ and python http://code.google.com/a/apache-extras.org/p/cassandra-dbapi2/ drivers. Cheers - Aaron Morton Freelance Cassandra Developer New Zealand @aaronmorton http://www.thelastpickle.com On 16/11/2012, at 11:21 AM, Timmy Turner timm.t...@gmail.com wrote: Does the official/built-in Cassandra CQL client (in 1.2) offer any built-in option to get direct values/objects when reading a field, instead of just a byte array?
Datatype Conversion in CQL-Client?
Does the official/built-in Cassandra CQL client (in 1.2) offer any built-in option to get direct values/objects when reading a field, instead of just a byte array?
Re: Admin for cassandra?
I think an eclipse plugin would be the wrong way to go here. Most people probably just want to browse through the columnfamilies and see whether their queries work out or not. This functionality is imho best implemented as some form of a light-weight editor, not a full blown IDE. I do have something of this kind scheduled as small part of a larger project (seeing as how there is currently no properly working tool that provides this functionality), but concrete results are probably still a few months out.. 2012/11/16 Edward Capriolo edlinuxg...@gmail.com We should build an eclipse plugin named Eclipsandra or something. On Thu, Nov 15, 2012 at 9:45 PM, Wz1975 wz1...@yahoo.com wrote: Cqlsh is probably the closest you will get. Or pay big bucks to hire someone to develop one for you:) Thanks. -Wei Sent from my Samsung smartphone on ATT Original message Subject: Admin for cassandra? From: Kevin Burton rkevinbur...@charter.net To: user@cassandra.apache.org CC: Is there an IDE for a Cassandra database? Similar to the SQL Server Management Studio for SQL server. I mainly want to execute queries and see the results. Preferably that runs under a Windows OS. Thank you.
describe columnfamilies?
Using a describe columnfamilies/tables query, Cassandra only gives me empty in 1.2.0-beta1 and the error mentioned in https://issues.apache.org/jira/browse/CASSANDRA-4946 in 1.2.0-beta2, despite there actually being columnfamilies in the currently selected/used keyspace. Selecting/updating the columnfamilies and describe columnfamily statements work fine. Is this a bug that will eventually be fixed, or does describe columnfamilies only list the columnfamilies after certain conditions (e.g. only after they've been flushed to the disk) have been met? If so, what are these conditions, and is there any way to force Cassandra to execute the necessary steps to meet these conditions?
Re: CQL3: Unknown property 'comparator'?
CQL 3 is not locked, the more feedback the better. I'm pretty sure that my use case is not relevant enough to consider special cases for it in Cassandra/CQL. In fact it's quite the other way around - it's my job to determine how well my tool fits Cassandra an other databases. Can you provide details on the use case? Basically what I tried to do was some sort of transparent client-side encryption, for those few that want to run their database in the cloud, but are too paranoid to do so - i.e. hook the Cassandra (CQL) library, parse the query myself (using a parser generated by Cassandra's own grammar definition), extract the values the user said he wanted encrypted (he did so in a configuration file), encrypt them, replace the original values with the encrypted ones in the query string, and hand it over to the actual CQL client library. If a result set came back, then I decrypted it before ultimately handing it over to the user. I also had the option to encrypt column names with individual keys per tuple, so they wouldn't result in the same ciphertext across tuples (for those ultra-paranoid users). Other than severely limiting the functionality of Cassandra (i.e. a user couldn't select specific columns any more, if more than one tuple was to be queried from the database; but queries for one specific tuple would still work without any kind of limitation), this worked fine in CQL2. In CQL3 this, obviously, isn't possible any more, if the users won't settle for using composite keys instead of columns. AFAIK to be schema free you use the row-column-value model. While this looks like many rows it is a single store engine row. I know. CQL3 is still a superset of CQL2's features, so in theory it can still do everything CQL2 could - but the real question is how Cassandra users will end up using it, and what kind of usage patterns the current data model encourages. 2012/10/30 aaron morton aa...@thelastpickle.com: My use case relied on mangling the column names for various Can you provide details on the use case? CQL 3 is not locked, the more feedback the better. That's not a problem, but I still needed a definitive statement that schema-free tables (not column families obviously) are now impossible within CQL, that I can document in the project as the reason for the changes. AFAIK to be schema free you use the row-column-value model. While this looks like many rows it is a single store engine row. Cheers - Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 30/10/2012, at 8:45 PM, Timmy Turner timm.t...@gmail.com wrote: Is your use case covered in the article above ? My use case relied on mangling the column names for various purposes, and CQL3 with its transposed columns does of course still allow for that, but it means rewriting the part of the application that dealt with CQL so it can handle the new syntax/data model. That's not a problem, but I still needed a definitive statement that schema-free tables (not column families obviously) are now impossible within CQL, that I can document in the project as the reason for the changes. Thanks! 2012/10/30 aaron morton aa...@thelastpickle.com: More background http://www.datastax.com/dev/blog/thrift-to-cql3 So does this mean that in CQL 3 an explicit schema is absolutely mandatory? Not really, it sort of depends on your view. Lets say this is a schema free CF definition in CLI create column family clicks with key_validation_class = UTF8Type and comparator = DateType and default_validation_class = UTF8Type It could be used for wide rows with lots of columns, where the name is a date. As the article at the top says, this CQL 3 DDL is equivalent: CREATE TABLE clicks ( key text, column1 timestamp, value text, PRIMARY KEY (key, column) ) WITH COMPACT STORAGE This creates a single row inside C*, column name is a date. The difference is CQL 3 pivots this one storage engine row into multiple CQL 3 rows. (See article) So far so good. Let's add some schema: CREATE TABLE clicks ( user_id text, click_time timestamp, click_url text, PRIMARY KEY (user_id, click_time) ) WITH COMPACT STORAGE That's functionally the same but has some more schema in it. It tells CQL 3 that the label to use for the name of a column is click_time. Previously the label was column1. It's now impossible (within CQL) to add new (non-primary-key) columns only for individual rows implicitly with DML-queries (insert/update)?. Is your use case covered in the article above ? Cheers - Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 30/10/2012, at 2:31 AM, Timmy Turner timm.t...@gmail.com wrote: Thank you! That article helps clear up a lot of my confusion about the changes between CQL 2 and 3, since I was wondering how to access/manipulate
Re: Create CF with composite column through CQL 3
CQL3 handles columns/rows/keys differently than Cassandra itself underneath. If you look closely you'll see that your real primary key is in fact only a Long: Key Validation Class: org.apache.cassandra.db.marshal.LongType If you want to know more about it, check these 2 articles: http://www.datastax.com/dev/blog/cql3-for-cassandra-experts http://www.datastax.com/dev/blog/thrift-to-cql3 (Also note that there are differences in CQL3 between 1.1 an 1.2.) This caused a bit of confusion for myself too a few days ago. It should really be documented somewhere in the wiki (as a CQL upgrade guide or something), not just be mentioned in the Datastax blog. 2012/10/31 Wei Zhu wz1...@yahoo.com: I try to use CQL3 to create CF with composite columns, CREATE TABLE Friends ( ... user_id bigint, ... friend_id bigint, ... status int, ... source int, ... created timestamp, ... lastupdated timestamp, ... PRIMARY KEY (user_id, friend_id, status, source) ... ); When I check it with cli, the composite type is a bit odd, why it's defined as Long, Int32, Int32, UTF8, is it supposed to be Long, Long, Int32, Int32? Did I do something wrong? describe friends; ColumnFamily: friends Key Validation Class: org.apache.cassandra.db.marshal.LongType Default column value validator: org.apache.cassandra.db.marshal.UTF8Type Columns sorted by: org.apache.cassandra.db.marshal.CompositeType( org.apache.cassandra.db.marshal.LongType, org.apache.cassandra.db.marshal.Int32Type, org.apache.cassandra.db.marshal.Int32Type, org.apache.cassandra.db.marshal.UTF8Type) GC grace seconds: 864000 Compaction min/max thresholds: 4/32 Read repair chance: 0.1 DC Local Read repair chance: 0.0 Replicate on write: true Caching: KEYS_ONLY Bloom Filter FP chance: default Built indexes: [] Compaction Strategy: org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy Compression Options: sstable_compression: org.apache.cassandra.io.compress.SnappyCompressor Thanks. -Wei
Re: CQL3: Unknown property 'comparator'?
Is your use case covered in the article above ? My use case relied on mangling the column names for various purposes, and CQL3 with its transposed columns does of course still allow for that, but it means rewriting the part of the application that dealt with CQL so it can handle the new syntax/data model. That's not a problem, but I still needed a definitive statement that schema-free tables (not column families obviously) are now impossible within CQL, that I can document in the project as the reason for the changes. Thanks! 2012/10/30 aaron morton aa...@thelastpickle.com: More background http://www.datastax.com/dev/blog/thrift-to-cql3 So does this mean that in CQL 3 an explicit schema is absolutely mandatory? Not really, it sort of depends on your view. Lets say this is a schema free CF definition in CLI create column family clicks with key_validation_class = UTF8Type and comparator = DateType and default_validation_class = UTF8Type It could be used for wide rows with lots of columns, where the name is a date. As the article at the top says, this CQL 3 DDL is equivalent: CREATE TABLE clicks ( key text, column1 timestamp, value text, PRIMARY KEY (key, column) ) WITH COMPACT STORAGE This creates a single row inside C*, column name is a date. The difference is CQL 3 pivots this one storage engine row into multiple CQL 3 rows. (See article) So far so good. Let's add some schema: CREATE TABLE clicks ( user_id text, click_time timestamp, click_url text, PRIMARY KEY (user_id, click_time) ) WITH COMPACT STORAGE That's functionally the same but has some more schema in it. It tells CQL 3 that the label to use for the name of a column is click_time. Previously the label was column1. It's now impossible (within CQL) to add new (non-primary-key) columns only for individual rows implicitly with DML-queries (insert/update)?. Is your use case covered in the article above ? Cheers - Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 30/10/2012, at 2:31 AM, Timmy Turner timm.t...@gmail.com wrote: Thank you! That article helps clear up a lot of my confusion about the changes between CQL 2 and 3, since I was wondering how to access/manipulate CompositeType/DynamicCompositeType columns through CQL. So does this mean that in CQL 3 an explicit schema is absolutely mandatory? It's now impossible (within CQL) to add new (non-primary-key) columns only for individual rows implicitly with DML-queries (insert/update)?. 2012/10/29 Sylvain Lebresne sylv...@datastax.com: CQL3 does absolutely allow dynamic column families, but does it differently from CQL2. See http://www.datastax.com/dev/blog/cql3-for-cassandra-experts. -- Sylvain On Mon, Oct 29, 2012 at 12:34 PM, Timmy Turner timm.t...@gmail.com wrote: Does CQL3 not allow dynamic columns (column names) any more?
CQL3 Cell-Transposition - Client or Server Side?
Does the cell transposition that is necessary for CQL3 happen on the server side after the query execution, or is it something that the Cassandra/CQL-client does before ultimately handing over the result set to the caller?
CQL3: Unknown property 'comparator'?
Does CQL3 not allow dynamic columns (column names) any more?
Re: CQL3: Unknown property 'comparator'?
Thank you! That article helps clear up a lot of my confusion about the changes between CQL 2 and 3, since I was wondering how to access/manipulate CompositeType/DynamicCompositeType columns through CQL. So does this mean that in CQL 3 an explicit schema is absolutely mandatory? It's now impossible (within CQL) to add new (non-primary-key) columns only for individual rows implicitly with DML-queries (insert/update)?. 2012/10/29 Sylvain Lebresne sylv...@datastax.com: CQL3 does absolutely allow dynamic column families, but does it differently from CQL2. See http://www.datastax.com/dev/blog/cql3-for-cassandra-experts. -- Sylvain On Mon, Oct 29, 2012 at 12:34 PM, Timmy Turner timm.t...@gmail.com wrote: Does CQL3 not allow dynamic columns (column names) any more?
Re: idea drive layout - 4 drives + RAID question
I'm not sure whether the raid 0 gets you anything other than headaches should one of the drives fail. You can already distribute the individual Cassandra column families on different drives by just setting up symlinks to the individual folders. 2012/10/30 Ran User ranuse...@gmail.com: For a server with 4 drive slots only, I'm thinking: either: - OS (1 drive) - Commit Log (1 drive) - Data (2 drives, software raid 0) vs - OS + Data (3 drives, software raid 0) - Commit Log (1 drive) or something else? also, if I can spare the wasted storage, would RAID 10 for cassandra data improve read performance and have no effect on write performance? Thank you!
Roadmap/Changelog?
Hi everyone, I wrote a library/extension for Cassandra 0.8 a while back, and would like to update it to the current version now, however I can't really find any articles on what has changed in Cassandra. I read the changelog, but those points are too detailed, and it's hard to determine what impact they really have on the functionality. The last things I remember are that CQL v3 was scheduled for 1.1 and supercoloumns would be removed and replaced by compound columns (and included in CQL). Has that already happened? Also it would be interesting to know whether there is any kind of roadmap for Cassandra for new features or functionality that may be introduced in upcoming versions, or features that may be removed in future versions. Thanks!
