cql, then and now
TRANSCRIPT
CQL, ‘THEN AND NOW’
Cassandra London Feb, 20th 2012
Courtney [email protected]
@zcourtshttp://crlog.infogithub.com/zcourts
IN THE BEGINNING ...horrible thrift code here
AND THEN THERE WAS... ...better looking hector code here
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.
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)...
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
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)
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).
CQL V1.0.0 - DEBUT KEYWORDS
USE SELECT UPDATE DELETE TRUNCATE DROP BATCH
CREATE KEYSPACE CREATE COLUMNFAMILY CREATE INDEX
SPECIAL STATEMENTS
That’s right!No INSERT...?
10 total
TIME TELLS NO LIES, CQL V2 ALTER COLUMNFAMILY BATCH CREATE INDEX CREATE KEYSPACE CREATE COLUMNFAMILY CREATE TABLE (CASSANDRA-2743) DELETE DROP COLUMNFAMILY DROP INDEX DROP KEYSPACE INSERT SELECT TRUNCATE UPDATE USE
15 total
Create table is nothing more than an alias to create columnfamily
Rational: ‘create an alias to be friendlier to
existing tools’
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
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...
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