= Create SAI index
:description: Create SAI index for CQL table schema using `cqlsh`.

To create an SAI index, you must define the index name, table name, and column name for the column to be indexed. 
 
To create a simple SAI index:

[source, language-cql]
----
include::cassandra:example$CQL/sai/cyclist_semi_pro_sai_indices.cql[tag=createQuickStartIndices]
----

For most SAI indexes, the column name is defined in the `CREATE INDEX` statement that also uses `USING 'sai'`.
The SAI index options are defined in the `WITH OPTIONS` clause.
The `case_sensitive` option is set to `false` to allow case-insensitive searches.
The `normalize` option is set to `true` to allow searches to be normalized for Unicode characters.
The `ascii_only` option is set to `true` to allow searches to be limited to ASCII characters.

The `map` collection data type is the one exception, as shown in the xref:#map-collection-in-sai-index[example below].

== Partition key SAI error

SAI indexes cannot be created on the partition key, as a primary index already exists and is used for queries.
If you attempt to create an SAI on the partition key column, an error will be returned:

[tabs]
====
CQL::
+
--
[source,language-cql]
----
include::cassandra:example$CQL/sai/sai-error.cql[]
----
--

Result::
+
--
[source,console]
----
include::cassandra:example$RESULTS/sai/sai-error.result[]
----
--
====

== `map` collection in SAI index

Map collections do have a different format than other SAI indexes:

[source, sql]
----
include::cassandra:example$CQL/sai/index-sai-from-map-match.cql[]
----

== similarity-function for vector search

This example uses the following table:

[source, sql]
----
include::cassandra:example$CQL/sai/create-vector-table-cycling.cql[tag=createvstable]
----

To check if `comment_vector` has a particular similarity function set, use the `similarity-function` option set to one of the supported similarity functions: DOT_PRODUCT, COSINE, or EUCLIDEAN. The default similarity function is COSINE.

This index creates an index on the `comment_vector` column with the similarity function set to DOT_PRODUCT:

[source, console]
----
include::cassandra:example$CQL/sai/index-sai-similarity-function.cql[]
----

'''
Other resources

See xref:developing/cql/indexing/create-custom-index.adoc[CREATE CUSTOM INDEX] for more information about creating SAI indexes.