This is an update to my two previous posts: http://crlog.info/2011/03/29/cassandra-query-language-aka-cql-syntax/ AND http://crlog.info/2011/06/13/cassandra-query-language-cql-v1-0-0-updated/ If you're using versions of Cassandra prior v1.0 beta one of the above links may be more appropriate as little things may have changed here and there. The official doc is on Gitub in textile markup here https://github.com/apache/cassandra/blob/trunk/doc/cql/CQL.textile

Cassandra Query Language (CQL) v2.0

Table of Contents

Cassandra Query Language (CQL) v2.0
1. Table of Contents
2. USE
3. SELECT
  1. Specifying Columns
  2. Column Family
  3. Consistency Level
  4. Filtering rows
  5. Limits
4. ALTER TABLE
5. INSERT
  1. Column Family
  2. Consistency Level
  3. Timestamp
  4. TTL
  5. Specifying Columns and Row
  6. Updating Counter Columns
6. DELETE
  1. Specifying Columns
  2. Column Family
  3. Consistency Level
7. BATCH
8. TRUNCATE
9. CREATE KEYSPACE
10. CREATE COLUMNFAMILY
  1. Column Family Options
11. CREATE INDEX
12. DROP INDEX
13. DROP
14. Common Idioms
Versioning
Changes

USE

Synopsis:

<code> USE <KEYSPACE>;</code>

A USE statement consists of the USE keyword, followed by a valid keyspace name. Its purpose is to assign the per-connection, current working keyspace. All subsequent keyspace-specific actions will be performed in the context of the supplied value.

SELECT

Synopsis:

<code> SELECT [FIRST N] [REVERSED] <SELECT EXPR> FROM <COLUMN FAMILY> [USING <CONSISTENCY>] [WHERE <CLAUSE>] [LIMIT N];</code>

A SELECT is used to read one or more records from a Cassandra column family. It returns a result-set of rows, where each row consists of a key and a collection of columns corresponding to the query.

Specifying Columns

<code> SELECT [FIRST N] [REVERSED] name1, name2, name3 FROM ... SELECT [FIRST N] [REVERSED] name1..nameN FROM ...</code>

The SELECT expression determines which columns will appear in the results and takes the form of either a comma separated list of names, or a range. The range notation consists of a start and end column name separated by two periods (..). The set of columns returned for a range is start and end inclusive.

The FIRST option accepts an integer argument and can be used to apply a limit to the number of columns returned per row. When this limit is left unset it defaults to 10,000 columns.

The REVERSED option causes the sort order of the results to be reversed.

It is worth noting that unlike the projection in a SQL SELECT, there is no guarantee that the results will contain all of the columns specified. This is because Cassandra is schema-less and there are no guarantees that a given column exists.

Column Family

<code> SELECT ... FROM <COLUMN FAMILY> ...</code>

The FROM clause is used to specify the Cassandra column family applicable to a SELECT query.

bc. SELECT count(*) FROM …

The count aggregate function returns a single row, with a single column “count” whose value is the number of rows from the pre-aggregation resultset.

Currently, count is the only function supported by CQL.

Consistency Level

<code> SELECT ... [USING <CONSISTENCY>] ...</code>

Following the column family clause is an optional consistency level specification.

Filtering rows

<code> SELECT ... WHERE <KEY> = keyname AND name1 = value1 SELECT ... WHERE <KEY> >= startkey and <KEY> =< endkey AND name1 = value1 SELECT ... WHERE <KEY> IN ('<key>', '<key>', '<key>', ...)</code>

The WHERE clause provides for filtering the rows that appear in results. The clause can filter on a key name, or range of keys, and in the case of indexed columns, on column values. Key filters are specified using the KEY keyword or key alias name, a relational operator, (one of =, >, >=, <, and <=), and a term value. When terms appear on both sides of a relational operator it is assumed the filter applies to an indexed column. With column index filters, the term on the left of the operator is the name, the term on the right is the value to filter on.

Note: The greater-than and less-than operators (> and <) result in key ranges that are inclusive of the terms. There is no supported notion of “strictly” greater-than or less-than; these operators are merely supported as aliases to >= and <=.

Limits

<code> SELECT ... WHERE <CLAUSE> [LIMIT N] ...</code>

Limiting the number of rows returned can be achieved by adding the LIMIT option to a SELECT expression. LIMIT defaults to 10,000 when left unset.

ALTER TABLE

Synopsis:

bc. ALTER TABLE ADD ; ALTER TABLE ALTER TYPE ; ALTER TABLE DROP ;

An ALTER is used to manipulate with ColumnFamily columns. It allows you to add new columns, alter and drop existing columns. No results are returned.

INSERT

Synopsis:

<code> INSERT INTO <COLUMN FAMILY> (<KEY>, <col>, <col>, ...) VALUES (<key>, <val>, <val>, ...) [USING CONSISTENCY <LEVEL> [AND TIMESTAMP <timestamp>] [AND TTL <timeToLive>]];</code>

An INSERT is used to write one or more columns to a record in a Cassandra column family. No results are returned.

Unlike SQL, the semantics of INSERT and UPDATE are identical, in either case a record is created if none existed before, and updated when it does. For information on modifiers and types, see theUPDATE section below.

UPDATE

Synopsis:

<code> UPDATE <COLUMN FAMILY> [USING <CONSISTENCY> [AND TIMESTAMP <timestamp>] [AND TTL <timeToLive>]] SET name1 = value1, name2 = value2 WHERE <KEY> = keyname;</code>

An UPDATE is used to write one or more columns to a record in a Cassandra column family. No results are returned. Key can be given using KEY keyword or by alias set per ColumnFamily.

Column Family

<code> UPDATE <COLUMN FAMILY> ...</code>

Statements begin with the UPDATE keyword followed by a Cassandra column family name.

Consistency Level

<code> UPDATE ... [USING <CONSISTENCY>] ...</code>

Following the column family identifier is an optional consistency level specification.

Timestamp

bc. UPDATE … [USING TIMESTAMP ] …

UPDATE supports setting client-supplied optional timestamp for modification.

TTL

bc. UPDATE … [USING TTL ] …

UPDATE supports setting time to live (TTL) for each of the columns in UPDATE statement.

Specifying Columns and Row

<code> UPDATE ... SET name1 = value1, name2 = value2 WHERE <KEY> = keyname; UPDATE ... SET name1 = value1, name2 = value2 WHERE <KEY> IN ('<key>', '<key>', ...)</code>

Rows are created or updated by supplying column names and values in term assignment format. Multiple columns can be set by separating the name/value pairs using commas. Each update statement requires exactly one key to be specified using a WHERE clause and the KEY keyword or key alias.

Updating Counter Columns

<code> UPDATE ... SET name1 = name1 + <value> ... UPDATE ... SET name1 = name1 - <value> ...</code>

Counter columns can be incremented or decremented by an arbitrary numeric value though the assignment of an expression that adds or substracts the value.

DELETE

Synopsis:

<code> DELETE [COLUMNS] FROM <COLUMN FAMILY> [USING <CONSISTENCY>] WHERE <KEY> = keyname1 DELETE [COLUMNS] FROM <COLUMN FAMILY> [USING <CONSISTENCY>] WHERE <KEY> IN (keyname1, keyname2);</code>

A DELETE is used to perform the removal of one or more columns from one or more rows. Key can be given using KEY keyword or by alias set per ColumnFamily.

Specifying Columns

<code> DELETE [COLUMNS] ...</code>

Following the DELETE keyword is an optional comma-delimited list of column name terms. When no column names are specified, the remove applies to the entire row(s) matched by the WHERE clause

Column Family

<code> DELETE ... FROM <COLUMN FAMILY> ...</code>

The column family name follows the list of column names.

Consistency Level

<code> DELETE ... [USING <CONSISTENCY>] ...</code>

Following the column family identifier is an optional consistency level specification.

Specifying Rows

<code> DELETE ... WHERE <KEY> = keyname1 DELETE ... WHERE <KEY> IN (keyname1, keyname2)</code>

The WHERE clause is used to determine which row(s) a DELETE applies to. The first form allows the specification of a single keyname using the KEY keyword (or by key alias) and the = operator. The second form allows a list of keyname terms to be specified using the IN notation and a parenthesized list of comma-delimited keyname terms.

BATCH

Synopsis:

bc. BATCH BEGIN BATCH [USING CONSISTENCY [AND TIMESTAMP ]] INSERT or UPDATE or DELETE statements separated by semicolon or “end of line” APPLY BATCH

BATCH supports setting client-supplied optional global timestamp which will be used for each of the operations included in batch.

A single consistency level is used for the entire batch, it appears after the BEGIN BATCH statement, and uses the standard consistency level specification. Batch default to CONSISTENCY.ONE when left unspecified.

NOTE: While there are no isolation guarantees, UPDATE queries are atomic within a give record.

Example:

bc. BEGIN BATCH USING CONSISTENCY QUORUM INSERT INTO users (KEY, password, name) VALUES (‘user2’, ‘ch@ngem3b’, ‘second user’) UPDATE users SET password = ‘ps22dhds’ WHERE KEY = ‘user2’ INSERT INTO users (KEY, password) VALUES (‘user3’, ‘ch@ngem3c’) DELETE name FROM users WHERE key = ‘user2’ INSERT INTO users (KEY, password, name) VALUES (‘user4’, ‘ch@ngem3c’, ‘Andrew’) APPLY BATCH

TRUNCATE

Synopsis:

<code> TRUNCATE <COLUMN FAMILY></code>

Accepts a single argument for the column family name, and permanently removes all data from said column family.

CREATE KEYSPACE

Synopsis:

<code> CREATE KEYSPACE <NAME> WITH AND strategy_class = <STRATEGY> AND strategy_options.<OPTION> = <VALUE> [AND strategy_options.<OPTION> = <VALUE>];</code>

The CREATE KEYSPACE statement creates a new top-level namespace (aka “keyspace”). Valid names are any string constructed of alphanumeric characters and underscores, but must begin with a letter. Properties such as replication strategy and count are specified during creation using the following accepted keyword arguments:

keyword required description

strategy_options no Most strategies require additional arguments which can be supplied by appending the option name to the strategy_options keyword, separated by a colon (:). For example, a strategy option of “DC1” with a value of “1” would be specified as strategy_options:DC1 = 1; replication_factor for SimpleStrategy could bestrategy_options:replication_factor=3.

CREATE COLUMNFAMILY

Synopsis:

<code> CREATE COLUMNFAMILY <COLUMN FAMILY> (<KEY> <type> PRIMARY KEY [, name1 type, name2 type, ...]); CREATE COLUMNFAMILY <COLUMN FAMILY> (<KEY> <type> PRIMARY KEY [, name1 type, name2 type, ...]) [WITH keyword1 = arg1 [AND keyword2 = arg2 [AND ...]]];</code>

CREATE COLUMNFAMILY statements create new column family namespaces under the current keyspace. Valid column family names are strings of alphanumeric characters and underscores, which begin with a letter.

Specifying Key Type

<code> CREATE ... (<KEY> <type> PRIMARY KEY) ...</code>

When creating a new column family, you must specify key type. The list of possible key types is identical to column comparators/validators, (see Specifying Column Type). It’s important to note that the key type must be compatible with the partitioner in use, for example OrderPreservingPartitioner and CollatingOrderPreservingPartitioner both require UTF-8 keys. If you use name instead of KEY keyword, name alias will be set automatically.

Specifying Column Type (optional)

<code> CREATE ... (<KEY> <type> PRIMARY KEY, name1 type, name2 type) ...</code>

It is possible to assign columns a type during column family creation. Columns configured with a type are validated accordingly when a write occurs. Column types are specified as a parenthesized, comma-separated list of column term and type pairs. The list of recognized types are:

type description

ascii	ASCII character string
bigint	8-byte long
blob	Arbitrary bytes (no validation)
boolean	true or false
counter	Counter column, (8-byte long)
decimal	Variable-precision decimal
double	8-byte floating point
float	4-byte floating point
int	4-byte int
text	UTF8 encoded string
timestamp	Date + Time, encoded as 8 bytes since epoch
uuid	Type 1, or type 4 UUID
varchar	UTF8 encoded string
varint	Arbitrary-precision integer

Note: In addition to the recognized types listed above, it is also possible to supply a string containing the name of a class (a sub-class of AbstractType), either fully qualified, or relative to theorg.apache.cassandra.db.marshal package.

Column Family Options (optional)

<code> CREATE COLUMNFAMILY ... WITH keyword1 = arg1 AND keyword2 = arg2;</code>

A number of optional keyword arguments can be supplied to control the configuration of a new column family.

keyword default description

comparator	text	Determines sorting and validation of column names. Valid values are identical to the types listed in Specifying Column Type above.
comment	none	A free-form, human-readable comment.
row_cache_provider	SerializingCacheProvider if JNA is present, otherwise ConcurrentHashMapCacheProvider	A factory for the cache with which to back the row cache.
row_cache_size	0	Number of rows whose entire contents to cache in memory.
key_cache_size	200000	Number of keys per SSTable whose locations are kept in memory in “mostly LRU” order.
read_repair_chance	1.0	The probability with which read repairs should be invoked on non-quorum reads.
gc_grace_seconds	864000	Time to wait before garbage collecting tombstones (deletion markers).
default_validation	text	Determines validation of column values. Valid values are identical to the types listed inSpecifying Column Type above.
min_compaction_threshold	4	Minimum number of SSTables needed to start a minor compaction.
max_compaction_threshold	32	Maximum number of SSTables allowed before a minor compaction is forced.
row_cache_save_period_in_seconds	0	Number of seconds between saving row caches.
key_cache_save_period_in_seconds	14400	Number of seconds between saving key caches.
replicate_on_write	false

CREATE INDEX

Synopsis:

<code>CREATE INDEX [index_name] ON <column_family> (column_name);</code>

A CREATE INDEX statement is used to create a new, automatic secondary index for the named column.

DROP INDEX

Synopsis:

<code>DROP INDEX <INDEX_NAME></code>

A DROP INDEX statement is used to drop an existing secondary index. DROP INDEX statement will search all ColumnFamilies in the current Keyspace for specified index and delete it if found.

DROP

Synopsis:

<code>DROP <KEYSPACE|COLUMNFAMILY> namespace;</code>

DROP statements result in the immediate, irreversible removal of keyspace and column family namespaces.

Common Idioms

Specifying Consistency

<code> ... USING <CONSISTENCY> ...</code>

Consistency level specifications are made up the keyword USING, followed by a consistency level identifier. Valid consistency levels are as follows:

CONSISTENCY ANY
CONSISTENCY ONE (default)
CONSISTENCY QUORUM
CONSISTENCY ALL
CONSISTENCY LOCAL_QUORUM
CONSISTENCY EACH_QUORUM

Term specification

Terms are used in statements to specify things such as keyspaces, column families, indexes, column names and values, and keyword arguments. The rules governing term specification are as follows:

Any single quoted string literal (example: 'apple').
Unquoted alpha-numeric strings that begin with a letter (example: carrot).
Unquoted numeric literals (example: 100).
UUID strings in hyphen-delimited hex notation (example: 1438fc5c-4ff6-11e0-b97f-0026c650d722).

Terms which do not conform to these rules result in an exception.

How column name/value terms are interpreted is determined by the configured type.

type term

ascii	Any string which can be decoded using ASCII charset
text / varchar	Any string which can be decoded using UTF8 charset
uuid	Standard UUID string format (hyphen-delimited hex notation)
uuid	Standard UUID string format (hyphen-delimited hex notation)
uuid	The string `now`, to represent a type-1 (time-based) UUID with a date-time component based on the current time
uuid	Numeric value representing milliseconds since epoch
uuid	An iso8601 timestamp
int	Integer value capable of fitting in 8 bytes (same as bigint)
bigint	Integer value capable of fitting in 8 bytes
varint	Integer value of arbitrary size
bytea	Hex-encoded strings (converted directly to the corresponding bytes)

Versioning

Versioning of the CQL language adheres to the Semantic Versioning guidelines. Versions take the form X.Y.Z where X, Y, and Z are integer values representing major, minor, and patch level respectively. There is no correlation between Cassandra release versions and the CQL language version.

version description

Patch	The patch version is incremented when bugs are fixed.
Minor	Minor version increments occur when new, but backward compatible, functionality is introduced.
Major	The major version must be bumped when backward incompatible changes are introduced. This should rarely (if ever) occur.

Changes

Fri, 09 Sep 2011 11:43:00 -0500 - Jonathan Ellis
 * add int data type

Wed, 07 Sep 2011 09:01:00 -0500 – Jonathan Ellis

Updated version to 2.0; Documented row-based count()
Updated list of supported data types

Wed, 10 Aug 2011 11:22:00 -0500 – Eric Evans

Improved INSERT vs. UPDATE wording.
Documented counter column incr/descr.

Sat, 01 Jun 2011 15:58:00 -0600 – Pavel Yaskevich

Updated to support ALTER (CASSANDRA-1709)

Tue, 22 Mar 2011 18:10:28 -0700 – Eric Evans eevans@rackspace.com

Initial version, 1.0.0

zcourts

Cassandra Query Language (CQL) v2.0 reference

Cassandra Query Language (CQL) v2.0

Table of Contents

USE

SELECT

Specifying Columns

Column Family

Consistency Level

Filtering rows

Limits

ALTER TABLE

INSERT

UPDATE

Column Family

Consistency Level

Timestamp

TTL

Specifying Columns and Row

Updating Counter Columns

DELETE

Specifying Columns

Column Family

Consistency Level

Specifying Rows

BATCH

TRUNCATE

CREATE KEYSPACE

CREATE COLUMNFAMILY

Specifying Key Type

Specifying Column Type (optional)

Column Family Options (optional)

CREATE INDEX

DROP INDEX

DROP

Common Idioms

Specifying Consistency

Term specification

Versioning

Changes