SingleStore Managed Service

CREATE INDEX

Create an index on the specified table.

Syntax
CREATE [UNIQUE] INDEX <index_name> [index_type] ON <table_name> (<index_column_name>,...) [<index_option>]

<index_column_name>:
    <column_name> [ASC | DESC]

<index_type>:
    USING { BTREE | HASH }

<index_option>:
  | <index_type>
  | COMMENT '<string>'
  | UNENFORCED [RELY | NORELY]
Remarks
  • <index_name> is the name of the index you want to create.

  • <table_name> is the name of a table in a SingleStore DB database.

  • Columnstore indexes cannot be created using the CREATE INDEX statement. Columnstore indexes must be defined when the table is created using the CREATE TABLE statement (see CREATE TABLE).

  • Only hash indexes can be created on columnstore tables. These hash indexes may be unique and use single or multiple columns.

  • This command can be run on the master aggregator node, or a child aggregator node (see Node Requirements for SingleStore DB Commands ).

  • This command will attempt to run as an online operation, but in certain cases cannot. See ALTER TABLE for more information. Operations which must be run offline cannot be run on distributed tables.

  • Every unique index must have all the columns of the shard key. Without it, the database cannot guarantee uniqueness across distributed database partitions.

  • SingleStore DB supports online CREATE INDEX, which means that you can read and write while the table is being indexed. CREATE INDEX on a sharded table is always executed online. Note that online CREATE INDEX will not begin indexing the table, but it will wait until all DML queries that were already running on the table finish. This allows any in-progress queries to complete execution before indexing the table, and ensures consistency of results from queries on the table since the time of execution of CREATE INDEX. As soon as the in-progress reads and writes complete and the CREATE INDEX command begins indexing the table, new reads and writes will proceed as normal. This blocking period usually lasts approximately for milliseconds.

    If you are running frequent CREATE INDEX statements on a table and have a lot of long-running queries on that table, then your normal workload may experience some periods of delay since it blocks other queries from starting while it waits for completion of long-running queries.

    Refer to the Query Errors topic for resolving query timeout errors due to long running queries in a workload.

Example

In the following example, you add a single-column index and a multi-column index to the articles table, which is a columnstore table defined as follows.

CREATE TABLE articles (
    id INT UNSIGNED,
    month int UNSIGNED,
    year int UNSIGNED,
    title VARCHAR(200),
    body TEXT,
    SHARD KEY(title),
    KEY (id) USING CLUSTERED COLUMNSTORE,     
    UNIQUE KEY (title) USING HASH);

Add a single-column unique index:

CREATE INDEX id_index ON articles(id) USING HASH;

Add a multi-column index:

CREATE INDEX month_year_index ON articles(month,year) USING HASH;