CQL In Cassandra 1.0 (and beyond)

CQL In Cassandra 1.0 (and beyond) Big Data DC Meetup #5 October 17, 2011 Eric Evans eric@acunu.com @jericevans, @acunu

● Overview, history, motivation● Changes in CQL 2.0 (Cassandra 1.0)● Coming soon (?)● Drivers status

What?● Cassandra Query Language ● aka CQL ● aka /ˈsēkwəl/● Exactly like SQL (except where its not)● Introduced in Cassandra 0.8.0● Ready for production use

SQL? Almost.–- Inserts or updatesINSERT INTO Standard1 (KEY, col0, col1)VALUES (key, value0, value1) vs.–- Inserts or updatesUPDATE Standard1SET col0=value0, col1=value1 WHERE KEY=key

SQL? Almost.–- Get columns for a rowSELECT col0,col1 FROM Standard1 WHERE KEY=key–- Range of columns for a rowSELECT col0..colN FROM Standard1 WHERE KEY=key–- First 10 results from a range of columnsSELECT FIRST 10 col0..colN FROM Standard1 WHERE KEY=key–- Invert the sorting of resultsSELECT REVERSED col0..colN FROM Standard1 WHERE KEY=key

Interface Instability

(Un)ease of useColumn col = new Column(ByteBuffer.wrap(“name”.getBytes()));col.setValue(ByteBuffer.wrap(“value”.getBytes()));col.setTimestamp(System.currentTimeMillis());ColumnOrSuperColumn cosc = new ColumnOrSuperColumn();cosc.setColumn(col);Mutation mutation = new Mutation();Mutation.setColumnOrSuperColumn(cosc);List mutations = new ArrayList<Mutation>();mutations.add(mutation);Map mutations_map = new HashMap<ByteBuffer, Map<String, List<Mutation>>>();Map cf_map = new HashMap<String, List<Mutation>>();cf_map.set(“Standard1”, mutations);mutations.put(ByteBuffer.wrap(“key”.getBytes()), cf_map)

CQLINSERT INTO Standard1 (KEY, col0) VALUES (key, value0)

Why? How about...● Better stability guarantees● Easier to use (you already know it)● Better code readability / maintainability

Why? How about...● Better stability guarantees● Easier to use (you already know it)● Better code readability / maintainability● Irritates the NoSQL purists

Why? How about...● Better stability guarantees● Easier to use (you already know it)● Better code readability / maintainability● Irritates the NoSQL purists● (Still )irritates the SQL purists

CQL 2.0

Wait, 2.0? You call that stable?Yes yes, but... ● We had a few FUBARs in the first pass ● Not the norm, honest ● Its a mulligan ● Look, cats!

Changed in 2.0● SELECT count(...) FROM now returns row, not column count● Terms / Types ● bytea became blob ● int became 4-bytes (was arbitrary precision) ● date became timestamp

Also new (but not breaking)● Named keys (virtual columns)● Counters● Complete DDL support● Timestamps and TTLs

Named Keys–- An unnamed key uses the KEY keywordCREATE TABLE Standard1 (KEY text PRIMARY KEY)–- But you can also name one like so...CREATE TABLE Standard1 (username text PRIMARY KEY)–- The name will also be used in results!SELECT email FROM Standard1 WHERE username = jericevans

Counters–- Counter incrementUPDATE Standard1SET acount = acount + 1 WHERE KEY = key–- Counter decrementUPDATE Standard1SET acount = acount - 1 WHERE KEY = key–- 1 not enough? Go nuts.UPDATE Standard1SET acount = acount + 9 WHERE KEY = key

Timestamps and TTLs–- Inserts or updatesUPDATE CFam USING TIMESTAMP 131851901600SET col0=value0, col1=value1 WHERE KEY=key–- Inserts or updatesUPDATE CFam USING TTL 86400SET col0=value0, col1=value1 WHERE KEY=key

Coming Soon(ish)

Roadmap● Prepared statements (CASSANDRA-2475)● Compound columns (CASSANDRA-2474)● Custom transport / protocol (CASSANDRA-2478)● Performance testing (CASSANDRA-2268)● Schema introspection (CASSANDRA-2477)● Multiget support (CASSANDRA-3069)

Drivers

Drivers● Hosted on Apache Extras (Google Code)● Tagged cassandra and cql● Licensed using Apache License 2.0● Conforming to a standard for database connectivity (if applicable)● Coming soon, automated testing and acceptance criteria

DriversDriver Platform Statuscassandra-jdbc Java Goodcassandra-dbapi2 Python Goodcassandra-ruby Ruby Newcassandra-pdo PHP Newcassandra-node Node.js Goodhttp://code.google.com/a/apache-extras.org/hosting/search?q=label%3aCassandra

The End

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CQL In Cassandra 1.0 (and beyond)

by Eric Evans

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