CQL, and the Road to Redemption

Transcription

1 CQL, and the Road to Redemption Eric Evans Cassandra Summit August 8, 2012 #cassandra12

2 Cassandra Query Language (aka CQL) Query language for Apache Cassandra SQL for the most part An alternative query interface Available since Cassandra 0.8.0

3

4

5 Best Troll Ever?

6 Not a troll at all, actually.

7 Status Quo RPC-based query interface Implemented in Thrift Compact binary serialization Loads of supported languages Generated language code Low level; very little abstraction

8 Unstable Relax NOT AGAIN! It ll take you 5 minutes to update your code.

9 Not User Friendly

10 This cannot be unseen! // Your column Column col = new Column(ByteBuffer.wrap( name.getbytes())); col.setvalue(bytebuffer.wrap( value.getbytes())); col.settimestamp(system.currenttimemillis()); // Don t ask ColumnOrSuperColumn cosc = new ColumnOrSuperColumn(); cosc.setcolumn(cosc); // Hang on, here we go... Mutation mutation = new Mutation(); mutation.setcolumnorsupercolumn(cosc); List<Mutation> mutations = new ArrayList<Mutation>(); mutations.add(mutation); Map mutations_map = new HashMap<ByteBuffer, Map<String, List<Mutation>>>(); Map cf_map = new Map<String, List<Mutation>>(); cf_map.set( Standard1, mutations); mutations_map.put(bytebuffer.wrap( key.getbytes()), cf_map); cassandra.batch_mutate(mutations_map, consistency_level);

11 This cannot be unseen! // Your column Column col = new Column(ByteBuffer.wrap( name.getbytes())); col.setvalue(bytebuffer.wrap( value.getbytes())); col.settimestamp(system.currenttimemillis()); // Don t ask ColumnOrSuperColumn cosc = new ColumnOrSuperColumn(); cosc.setcolumn(cosc); // Hang on, here we go... Mutation mutation = new Mutation(); mutation.setcolumnorsupercolumn(cosc); List<Mutation> mutations = new ArrayList<Mutation>(); mutations.add(mutation); Map mutations_map = new HashMap<ByteBuffer, Map<String, List<Mutation>>>(); Map cf_map = new Map<String, List<Mutation>>(); cf_map.set( Standard1, mutations); mutations_map.put(bytebuffer.wrap( key.getbytes()), cf_map); cassandra.batch_mutate(mutations_map, consistency_level);

12 A query interface should be... Simple Intuitive Invisible Performant(?)

13 Alternatives REST RPC (Thrift, Avro, Protobuf, etc) SQL (bahahaha) etc, etc

14 REST Pros Ubiquitous Frequently requested Client uniformity Cons Fails expectations Slow

15 RPC Pros Easy to implement Performant Cons Poor mental fit Heavy dependency

16 SQL Pros Ubiquitous Widely known Excellent mental fit Client uniformity Cons People whinging Security(?)

17 SQL Pros Ubiquitous Widely known Excellent mental fit Client uniformity Cons People whinging Security(?)

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19 Hello Create or update INSERT INTO users (id, given, surname) VALUES (jericevans, Eric, Evans); -- Create or update UPDATE users SET given = Eric, surname = Evans WHERE id = jericevans; SELECT surname, given FROM users WHERE id = jericevans;

20 ...is it me you re looking for? -- Adding an index CREATE INDEX surnameidx ON users (surname); SELECT id, given FROM users WHERE surname = Evans; -- Limiting the number of rows SELECT id, given FROM users WHERE surname = Evans LIMIT 1000;

21 Querying column ranges -- From column, to column SELECT FROM News WHERE topic = cassandra -- Last N columns SELECT FIRST 10 REVERSED * FROM News WHERE topic = cassandra

22 Counting -- Get your count on UPDATE inventory SET apples = apples + 1 WHERE id = fruit; UPDATE inventory SET carrots = carrots - 1 WHERE id = vegetable;

23 Batching writes BEGIN BATCH INSERT INTO msgs (owner, subject, body) VALUES(jericevans, Hi, Howdy ); UPDATE subjects SET subject = now WHERE owner = jericevans APPLY BATCH

24 A query interface should be... Simple Intuitive Invisible Performant(?)

25 Drivers Not (necessarily) a replacement for high-level, idiomatic libraries Avoids duplicating efforts, (error handling, pooling, etc) Consistently scoped, JDBC, etc Consistently hosted, licensed Discoverable More work needed...

26 Current lineup JDBC (Java) DB-API 2 (Python) PDO (PHP) Ruby Node.JS

27 And what about interface stability?

28 0.8.0 CQL 1.0

29 CQL types made more consistent w/ SQL count() returns rows, not columns

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31 CQL

32 CQL A materialized timeline of tweets CREATE COLUMNFAMILY timeline ( username text, posted_at timestamp, body text, posted_by text, PRIMARY KEY (username, posted_at) );

33 CQL 3.0 INSERT INTO timeline (username, posted_at, body, posted_by) VALUES (scotty, :36 stupid klingons..., jtkirk); INSERT INTO timeline (username, posted_at, body, posted_by) VALUES (scotty, green?, spock); INSERT INTO timeline (username, posted_at, body, posted_by) VALUES (scotty, yes, green, jtkirk); INSERT INTO timeline (username, posted_at, body, posted_by) VALUES (scotty, :14 get off my lawn!, bones);

34 In Cassandra s eyes eye scotty (23/03 14:36, body): stupid klingons... (23/03 14:36, posted_by): jtkirk (23/03 16:12, green?...

35 -- Tweets in Scotty s timeline, by date SELECT * FROM timeline WHERE username = scotty AND posted_at > ;

36 Is it a row, or a table? Yes. username posted_at body posted_by scotty 23/03 14:36 stupid klingons... jtkirk scotty 23/03 green? spock scotty 23/03 yes, green jtkirk scotty 25/03 08:14 get off my lawn! bones

37 Also... Column names are strictly UTF-8 Column names are case-insensitive (unless quoted) Old slice notation is gone (<start>..<end>) Static column families are actually static (schema-enforced)

38 NOT AGAIN!

39 CQL beta You are here x

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41 CQL 3.0 You will be here x 1.2.0

42 A query interface should be... Simple Intuitive Invisible Performant(?)

43 Performance inserts

44 Performance inserts w/ index

45 Performance counter increments

46 Performance reads

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48 A query interface should be... Simple Intuitive Invisible Performant

49 Help Wanted Writing tests Documentation Feedback Drivers

50 #cassandra12