Configure Spanner columnar engine

This page describes how to enable Spanner columnar engine on a database, table, or index, and accelerate file format generation.

Enable Spanner columnar engine

Spanner columnar engine is enabled using a SET OPTIONS clause with the columnar_policy option. You can apply this option when you create or alter DATABASE, TABLE, or INDEX schema objects. SEARCH INDEX and VECTOR INDEX schema objects are never in columnar format.

Lower levels in a database and table hierarchy inherit the columnar_policy from its parent. You can change this setting at lower levels.

The columnar_policy option has the following flags:

  • 'enabled' or 'disabled' turns the columnar engine on or off for the specific schema object.
  • NULL (default) uses the columnar engine policy from the parent object, if one exists. NULL clears previous settings on a table object.

You can also omit OPTIONS to inherit the columnar_policy from the parent object.

The following example shows how to:

  • Create a database with the columnar policy enabled.
  • Define a Singers table that inherits the columnar policy from the database (omit the columnar_policy = NULL for the table option).
  • Define a Concerts table with the columnar policy explicitly disabled.
CREATE DATABASE Music;

ALTER DATABASE Music SET OPTIONS (columnar_policy = 'enabled');

CREATE TABLE Singers(
  SingerId INT64 NOT NULL,
  FirstName STRING(1024),
  LastName STRING(1024),
  BirthDate DATE,
  Status STRING(1024),
  LastUpdated TIMESTAMP,)
  PRIMARY KEY(SingerId);

CREATE TABLE Concerts(
  VenueId INT64 NOT NULL,
  SingerId INT64 NOT NULL,
  ConcertDate DATE NOT NULL,
  BeginTime TIMESTAMP,
  EndTime TIMESTAMP,)
  PRIMARY KEY(VenueId, SingerId, ConcertDate),
  OPTIONS (columnar_policy = 'disabled');

You can also use ALTER TABLE with the SET OPTIONS clause to enable or disable the columnar_policy on a table. The following example shows how to disable the policy in the Singers table:

ALTER TABLE Singers SET OPTIONS (columnar_policy = 'disabled');

Columnar file format generation

Spanner generates the columnar file format at compaction time. Compaction is a background process that typically is spread out over multiple days, but it might happen sooner if the size of the database grows substantially. For more information, see Optimal columnar coverage.

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