ALTER KEYSPACE
Changes keyspace replication and enable/disable commit log.
Modifies the keyspace replication strategy, the number of copies of the data Cassandra creates in each data center, REPLICATION, and/or disable the commit log for writes, DURABLE_WRITES.
Restriction: Changing the keyspace name is not supported.
Synopsis
ALTER KEYSPACE keyspace_name
WITH REPLICATION = {
'class' : 'SimpleStrategy', 'replication_factor' : N
| 'class' : 'NetworkTopologyStrategy', 'dc1_name' : N [, ...]
}
[AND DURABLE_WRITES = true|false] ;
Syntax conventions | Description |
---|---|
UPPERCASE | Literal keyword. |
Lowercase | Not literal. |
Italics |
Variable value. Replace with a user-defined value. |
[] |
Optional. Square brackets ( [] ) surround optional command
arguments. Do not type the square brackets. |
( ) |
Group. Parentheses ( ( ) ) identify a group to choose from. Do
not type the parentheses. |
| |
Or. A vertical bar ( | ) separates alternative elements. Type
any one of the elements. Do not type the vertical bar. |
... |
Repeatable. An ellipsis ( ... ) indicates that you can repeat
the syntax element as often as required. |
'Literal string' |
Single quotation ( ' ) marks must surround literal strings in
CQL statements. Use single quotation marks to preserve upper case. |
{ key : value } |
Map collection. Braces ( { } ) enclose map collections or key
value pairs. A colon separates the key and the value. |
<datatype1,datatype2> |
Set, list, map, or tuple. Angle brackets ( < > ) enclose
data types in a set, list, map, or tuple. Separate the data types with a comma.
|
cql_statement; |
End CQL statement. A semicolon ( ; ) terminates all CQL
statements. |
[--] |
Separate the command line options from the command arguments with two hyphens (
-- ). This syntax is useful when arguments might be mistaken for
command line options. |
' <schema> ... </schema> ' |
Search CQL only: Single quotation marks ( ' ) surround an
entire XML schema declaration. |
@xml_entity='xml_entity_type' |
Search CQL only: Identify the entity and literal value to overwrite the XML element in the schema and solrConfig files. |
- REPLICATION
-
Important: Use only replication strategy implementations bundled with DSE.
Simple strategy
Assign the same replication factor to the entire cluster. Use for evaluation and single data center test and development environments only.REPLICATION = { 'class' : 'SimpleStrategy', 'replication_factor' : N }
Network topology strategy
Assign replication factors to each data center in a comma separated list. Use in production environments and multi-DC test and development environments. Data center names must match the snitch DC name; refer to Snitches for more details.REPLICATION = { class' : 'NetworkTopologyStrategy', 'datacenter_name' : N [, 'datacenter_name' : N] }
Note: Datacenter names are case sensitive. Verify the case of the using utility, such asdsetool status
. - DURABLE_WRITES
- Optionally (not recommended), bypass the commit log when
writing to the keyspace by disabling durable writes (DURABLE_WRITES = false). Default
value is
true
.CAUTION:Never disable durable writes when using SimpleStrategy replication.
Example
Change the cycling
keyspace to NetworkTopologyStrategy
in
a single data center and turn off durable writes (not recommended). This example uses the
default data center name in Cassandra with a replication factor of 3.
ALTER KEYSPACE cycling WITH REPLICATION = { 'class' : 'NetworkTopologyStrategy', 'datacenter1' : 3 } AND DURABLE_WRITES = false ;