Previously posted here http://www.slideshare.net/shotaz/cql-cassandra-query-language slideshare doesn't allow updating usernames so I got a new account. More detailed info on CQL see http://crlog.info/2011/09/17/cassandra-query-language-cql-v2-0-reference/

1. CQL – CASSANDRA QUERY LANGUAGE
Courtney Robinson – crlog.info
@ Eric Evans (Python tests and CQL Spec)

2. THRIFT OR AVRO?
 External dependency
 Community activity dissipates
 Too generic
 Many user reported problems caused by Thrift or
the misuse thereof...
Its thrift!
Its Avro!
Its CQL....

3. WHAT IS IT?
 Effectively a structured query language
 Replacement for clients? Not really...
 Attempting to push as much server-side as possible
 Familiar syntax
 User friendly API for Cassandra new comers

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

5. SPECIFYING CONSISTENCY
 ... USING <CONSISTENCY> ...
 Made up of the keyword USING, followed by a consistency level identifier.
 Valid consistency levels are:
 CONSISTENCY ZERO
 CONSISTENCY ONE (default)
 CONSISTENCY QUORUM
 CONSISTENCY ALL
 CONSISTENCY DCQUORUM
 CONSISTENCY DCQUORUMSYNC
 E.g BEGIN BATCH USING CONSISTENCY ONE

6. CREATE KEYSPCE
 CREATE KEYSPACE WITH replication_factor = AND strategy_class = [AND
strategy_options. = [AND strategy_options. = ]];
 E.g CREATE KEYSPACE TestKeyspace WITH strategy_options:DC1 = '1‘ AND
strategy_class = 'NetworkTopologyStrategy‘
CREATE COLUMN FAMILY
 CREATE COLUMNFAMILY [(name1 type, name2 type, ...)] [WITH keyword1 = arg1 [AND
keyword2 = arg2 [AND ...]]];
Set column type:
 CREATE COLUMNFAMILY (name1 type, name2 type) ...;
CREATE INDEX
 CREATE INDEX [index_name] ON <column_family> (column_name);
 Used to create a new, automatic secondary index for the named column.

7. USE
 USE <KEYSPACE>;
 Use keyword followed by a valid Keyspace name
 Set working Keyspace per-connection
DROP
 DROP <KEYSPACE|COLUMNFAMILY>;
 DROP KEYSPACE KSName;
 DROP COLUMNFAMILY CFName;
Immediate, irreversible removal of keyspace and column family
namespaces.
TRUNCATE
 TRUNCATE <COLUMN FAMILY>
 Accepts a single argument (CF) name
 permanently removes all data from said column family.

8. UPDATE (values)
 UPDATE [USING CONSISTENCY ]
SET name1 = value1, name2 = value2 WHERE KEY = keyname;
 UPDATE is used to write one or more columns to a record in a Cassandra
column family.
 No results are returned.
 Creates or updates rows
 UPDATE CFName SET ‘name' = 10 WHERE KEY = ‘1234’
 UPDATE <COLUMN FAMILY> ...
 Begin with the UPDATE keyword followed by CF name.
 Followed by an optional consistency level specification.

9. BATCH UPDATES
 Where‟s my batch mutate gone?
 Similar to code blocks/structs
 Has begining (Begin Batch) and end (Apply Batch)
BEGIN BATCH [USING ]
UPDATE CF1 SET name1 = value1, name2 = value2 WHERE KEY = keyname1;
UPDATE CF1 SET name3 = value3 WHERE KEY = keyname2;
UPDATE CF2 SET name4 = value4, name5 = value5 WHERE KEY = keyname3;
APPLY BATCH
 BEGIN BATCH USING CONSISTENCY QUORUM
UPDATE CFname SET 1='1', 2='2', 3='3', 4='4' WHERE KEY='aa‘
UPDATE CFname2 SET 5='5', 6='6', 7='8', 9='9' WHERE KEY='ab'
UPDATE CFname SET 9='9', 8='8', 7='7', 6='6' WHERE KEY='ac'
UPDATE CFname3 SET 5='5', 4='4', 3='3', 2='2' WHERE KEY='ad'
UPDATE CFname SET 1='1', 2='2', 3='3', 4='4' WHERE KEY='ae'
 APPLY BATCH

10. DELETE
 DELETE [COLUMNS] FROM [USING ] WHERE KEY =
keyname1
 DELETE [COLUMNS] FROM [USING ] WHERE KEY IN
(keyname1, keyname2);
o Remove one or more columns from one or more rows.
o Optional comma-delimited list of column names following
DELETE
o Removes entire row(s) if no columns are specified
o DELETE „col1', 'col2' FROM CF WHERE KEY = 'key„
o
DELETE „col1', 'col2' FROM CF WHERE KEY = ('key„, „key2‟,
„key3‟)

11. SELECT
 SELECT [FIRST N] [REVERSED] <SELECT EXPR> FROM <COLUMN FAMILY>
[USING <CONSISTENCY>] [WHERE <CLAUSE>] [LIMIT N];
 FIRST = number of columns, N
 REVERSED = Reverses sort order
 Return a result set, key + columns per row
Specify columns:
 SELECT [FIRST N] [REVERSED] name1, name2, name3 FROM ...
Request a range of columns:
 SELECT [FIRST N] [REVERSED] name1..nameN FROM ...
 “..” Notation specifies range
 Inclusive of start and end columns
 E.g SELECT FIRST 2 REVERSED 3..1 FROM CF WHERE KEY = 'aa'

12. COURTNEY ROBINSON @ZCOURTS
Thank you for listening.
Questions?
Links:
http://crlog.info/2011/03/29/cassandra-query-language-aka-cql-syntax/
https://svn.apache.org/viewvc/cassandra/trunk/doc/cql/CQL.html?view=co
https://issues.apache.org/jira/browse/CASSANDRA-1703