1. CQL, ‘THEN AND NOW’
Cassandra London
Feb, 20th 2012
Courtney Robinson
courtney@crlog.info
@zcourts
http://crlog.info
github.com/zcourts

2. IN THE BEGINNING
 ...horrible thrift code here

3. AND THEN THERE WAS...
 ...better looking hector code here

4. NOT QUITE
 ...slightly better (my hector wrapper)
 Still not excellent, but better (I think)
 Remember, not all languages have clients as good as
hector.
 Usability varied* vastly between the supported languages
 So much so I chose Play! Framework over PHP for a
small admin front end.

5. YAY! CQL TO SAVE THE DAY!
 ...because not everyone has an Ops team to torture.
 Upgrading wasn’t such a pain, little or no code breaking
 CQL offered stability (ish)...

6. BRIEF INTRO – WHAT IS IT?
 Simple, structured query language for Cassandra
 Very much SQL (except where it can’t be)
 Alternative to the Thrift RPC API.
 Available since Cassandra version 0.8.0
 In keeping with Eric Evan’s attempts, just pronounce it
‘siːkwəl’
 Isn’t much* to say about CQL, its does what it says on the
tin

7. CONTROVERSY, POLITICS AND OUT RIGHT BI***ING
 Always been an outspoken (some more than others)
few against it
 Never been much in the way of facts to backup their claims
such as:
 SQL like syntax is a very idiomatic RDMS thing.
 Parsing a string will be slow, just because its parsing a string
and for no other reason
 The aforementioned will make Cassandra ‘as vulnerable’ to
injection
 ...etc (all speculation mind you)

8. SO WHAT, CAN I USE THIS THING?
 CQL is very much production ready.
 If anyone tells you otherwise, ask them to prove its not before you
decide.
 My tiny 5 Node cluster is nothing to boast about, but it handles a good
150+ GB of data a day
 Every* query is done with CQL
 Except on a single CF which uses super columns.
 CQL does not and most likely will not ever support super columns.
 Compound column (CASSANDRA-2474 monster ticket) resolved (ish).

9. CQL V1.0.0 - DEBUT KEYWORDS
 USE
 SELECT
That’s right!
 UPDATE
 DELETE
No INSERT...?
 TRUNCATE
 DROP
 BATCH
SPECIAL STATEMENTS
 CREATE KEYSPACE
 CREATE COLUMNFAMILY
 CREATE INDEX 10
total

10. TIME TELLS NO LIES, CQL V2
 ALTER COLUMNFAMILY
 BATCH Create table is nothing more
than an alias to create
 CREATE INDEX
columnfamily
 CREATE KEYSPACE
 CREATE COLUMNFAMILY
 CREATE TABLE (CASSANDRA-2743)
 DELETE
Rational: ‘create an
 DROP COLUMNFAMILY alias to be friendlier
 DROP INDEX to existing tools’
 DROP KEYSPACE
 INSERT
 SELECT
 TRUNCATE 15
total
 UPDATE
 USE

11. CQL V3, AKA CASSANDRA-3761
 About 13 sub-tickets
 Most unresolved
 It’d be unwise to list features
 Any of these could be dropped/altered before V3 is
finalized (C* V1.1.1 is the roadmap release for V3)
 Backwards incompatibility (hence major version jump)
 Not the little project it used to be, would take all night to
cover each feature with enough details

12. TERMINOLOGY WAR...
 CQL’s changing fast (maybe too fast?)
 Terminology looks to be changing
 Creating over lap in some places
 May become, or already is confusing
 Not sure those in charge are seeing it
 At a stage where its probably as confusing as other, more
complicated C* features
 Progress is great, but so is usability & simplicity...

14. COURTNEY ROBINSON @ZCOURTS
Thank you for listening.
Questions?
Links:
https://github.com/apache/cassandra/blob/trunk/doc/cql/CQL.textile
http://crlog.info/2011/09/17/cassandra-query-language-cql-v2-0-reference/
https://issues.apache.org/jira/browse/CASSANDRA-2743