Synopsis:
USE <KEYSPACE>;
+Cassandra Query Language (CQL) v0.99.1
Table of Contents
- Cassandra Query Language (CQL) v0.99.1
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 ...
@@ -32,5 +32,6 @@ UPDATE ... WHERE KEY IN (keyname1, keyname2)
[AND keyword2 = arg2 [AND ...]]];
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 Column Type (optional)
CREATE COLUMNFAMILY <COLUMN FAMILY> (name1 type, name2 type) ...;
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 bytes Arbitrary bytes (no validation) ascii ASCII character string utf8 UTF8 encoded string timeuuid Type 1 UUID uuid Type 4 UUID int 4-byte integer long 8-byte long
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 the org.apache.cassandra.db.marshal package.
Column Family Options (optional)
CREATE COLUMNFAMILY ... WITH keyword1 = arg1 AND keyword2 = arg2;
-
A number of optional keyword arguments can be supplied to control the configuration of a new column family.
keyword default description comparator bytes 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 bytes 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
Common Idioms
Specifying Consistency
... USING <CONSISTENCY> ...
+
A number of optional keyword arguments can be supplied to control the configuration of a new column family.
keyword default description comparator bytes 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 bytes 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.
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
Where possible, the type of terms are inferred; the following term types are supported:
String Literals
String literals are any value enclosed in double-quotes, (`"`). String literals are treated as raw bytes; no interpolation is performed.
Unicode
Unicode terms are any double-quoted string prefixed with a lower-case u, for example u"© 2011 The Apache Software Foundation". Unicode terms are identical to standard string literals, with the exception that they are encoded to bytes using the UTF-8 charset.
Integers / longs
Integers are any term consisting soley of unquoted numericals, longs are any otherwise valid integer term followed by an upper case “L”, (e.g. 100L). It is an error to specify an integer term that will not fit in 4 bytes unsigned, or a long that will not fit in 8 bytes unsigned.
UUIDs
There are two types of UUIDs supported by the CQL specification, time-based (version 1) and randomly generated (version 4). These are specified in statements using the timeuuid(<UUID STRING>) and uuid(<UUID STRING>) notations respectively.
In addition to the hex-based string representation, timeuuid() terms also accept arguments to specify the data-time component. The full list of timeuuid() arguments are:
argument example behavior none timeuuid() Results in the creation of a new UUID based on system time of the node parsing the query. now timeuuid(“now”) Results in the creation of a new UUID based on system time of the node parsing the query. milliseconds since epoch timeuuid(1296755320376) Creates a UUID with a time component that is based on the supplied time-stamp. iso8601 timestamp timeuuid(“2011-02-01T14:00-0600”) Creates a UUID with a time component that is based on the supplied time-stamp. string representation (hex) timeuuid(“e9229b24-2fbe-11e0-a4de-0026c650d722”) Reproduces the specified version 1 UUID node-side.
\ No newline at end of file
diff --git a/doc/cql/CQL.textile b/doc/cql/CQL.textile
index 574893737f..27bc0ceac6 100644
--- a/doc/cql/CQL.textile
+++ b/doc/cql/CQL.textile
@@ -227,6 +227,14 @@ A number of optional keyword arguments can be supplied to control the configurat
|memtable_operations_in_millions|dynamic|Number of operations in millions before the memtable is flushed.|
|replicate_on_write|false| |
+h2. CREATE INDEX
+
+_Synopsis:_
+
+bc. CREATE INDEX [index_name] ON (column_name);
+
+A @CREATE INDEX@ statement is used to create a new, automatic secondary index for the named column.
+
h2. Common Idioms
h3(#consistency). Specifying Consistency