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 .

If you create a new database without data and enable columnar engine, Spanner stores data in columnar format as you insert it and as compactions occur in the background.

Columnar data format isn't generated for backups.

When you enable Spanner columnar engine on an existing database that has data in it, Spanner provides a mechanism to manually trigger compactions. For more information, see Manually trigger a data compaction .

What's next

• Learn about columnar engine .
• Learn how to query columnar data .
• Learn how to monitor columnar engine .