Synopsis:
USE <KEYSPACE>;
+Cassandra Query Language (CQL) v1.0.0
Table of Contents
- Cassandra Query Language (CQL) v1.0.0
- Versioning
- Changes
USE
Synopsis:
USE <KEYSPACE>;
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:
SELECT [FIRST N] [REVERSED] <SELECT EXPR> FROM <COLUMN FAMILY> [USING <CONSISTENCY>]
[WHERE <CLAUSE>] [LIMIT N];
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
SELECT [FIRST N] [REVERSED] name1, name2, name3 FROM ...
@@ -35,4 +35,6 @@ UPDATE ... WHERE KEY IN (keyname1, keyname2)
A number of optional keyword arguments can be supplied to control the configuration of a new column family.
keyword default description comparator utf8 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_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 utf8 Determines validation of column values. Valid values are identical to the types listed in Specifying 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. memtable_flush_after_mins 60 Maximum time to leave a dirty table unflushed. memtable_throughput_in_mb dynamic Maximum size of the memtable before it is flushed. memtable_operations_in_millions dynamic Number of operations in millions before the memtable is flushed. replicate_on_write false
CREATE INDEX
Synopsis:
CREATE INDEX [index_name] ON <column_family> (column_name);
A CREATE INDEX statement is used to create a new, automatic secondary index for the named column.
DROP
Synopsis:
DROP <KEYSPACE|COLUMNFAMILY> namespace;
DROP statements result in the immediate, irreversible removal of keyspace and column family namespaces.
Common Idioms
Specifying Consistency
... USING <CONSISTENCY> ...
-
Consistency level specifications are made up the keyword USING, followed by a consistency level identifier. Valid consistency levels are as follows:
CONSISTENCY ZEROCONSISTENCY ONE (default)CONSISTENCY QUORUMCONSISTENCY ALLCONSISTENCY DCQUORUMCONSISTENCY DCQUORUMSYNC
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 utf8 Any string which can be decoded using UTF8 charset uuid Standard UUID string format (hyphen-delimited hex notation) timeuuid Standard UUID string format (hyphen-delimited hex notation) timeuuid The string now, to represent a type-1 (time-based) UUID with a date-time component based on the current time timeuuid Numeric value representing milliseconds since epoch timeuuid An iso8601 timestamp long Numeric value capable of fitting in 8 bytes int Numeric value of arbitrary size bytes Hex-encoded strings (converted directly to the corresponding bytes)
\ No newline at end of file
+Consistency level specifications are made up the keyword USING, followed by a consistency level identifier. Valid consistency levels are as follows:
CONSISTENCY ZEROCONSISTENCY ONE (default)CONSISTENCY QUORUMCONSISTENCY ALLCONSISTENCY DCQUORUMCONSISTENCY DCQUORUMSYNCTerms 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:
'apple').carrot).100).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 |
| utf8 | Any string which can be decoded using UTF8 charset |
| uuid | Standard UUID string format (hyphen-delimited hex notation) |
| timeuuid | Standard UUID string format (hyphen-delimited hex notation) |
| timeuuid | The string now, to represent a type-1 (time-based) UUID with a date-time component based on the current time |
| timeuuid | Numeric value representing milliseconds since epoch |
| timeuuid | An iso8601 timestamp |
| long | Numeric value capable of fitting in 8 bytes |
| int | Numeric value of arbitrary size |
| bytes | Hex-encoded strings (converted directly to the corresponding bytes) |
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. |
Tue, 22 Mar 2011 18:10:28 -0700 - Eric Evans <eevans@rackspace.com> + * Initial version, 1.0.0 +\ No newline at end of file diff --git a/doc/cql/CQL.textile b/doc/cql/CQL.textile index 097cfb5067..f08be160bf 100644 --- a/doc/cql/CQL.textile +++ b/doc/cql/CQL.textile @@ -1,4 +1,4 @@ -h1. Cassandra Query Language (CQL) v0.99.1 +h1. Cassandra Query Language (CQL) v1.0.0 h2. Table of Contents @@ -283,3 +283,18 @@ How column name/value terms are interpreted is determined by the configured type |long|Numeric value capable of fitting in 8 bytes| |int|Numeric value of arbitrary size| |bytes|Hex-encoded strings (converted directly to the corresponding bytes)| + +h1. Versioning + +Versioning of the CQL language adheres to the "Semantic Versioning":http://semver.org 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.| + +h1. Changes + +pre. +Tue, 22 Mar 2011 18:10:28 -0700 - Eric Evans