pgroonga_vacuum function

Since 2.1.7.

Summary

pgroonga_vacuum function removes internal unused Groonga tables, columns and records. Note that it's not for PGroonga. It's for Groonga. Normally, you don't need to call this function because PGroonga does the same process on VACUUM.

You need to call this function one of the following situations:

• You remove all PGroonga indexes. If you don't have any PGroonga index, PGroonga can't run the same process on VACUUM.

• You use streaming replication. You need to call this function only on slaves because VACUUM isn't run on slaves.

Syntax

Here is the syntax of this function:

bool pgroonga_vacuum()

It always returns true. If there is a problem in processing, an error is raised.

Usage

Here are sample schema:

CREATE TABLE memos (
  content text
);

CREATE INDEX pgroonga_index ON memos USING PGroonga (content);

You keep the current internal Groonga table name. \gset and \echo are psql's meta commands:

SELECT pgroonga_table_name('pgroonga_index')
\gset old_
\echo :old_pgroonga_table_name
-- Sources17058

The current internal Groonga table is changed after REINDEX:

REINDEX INDEX pgroonga_index;
SELECT pgroonga_table_name('pgroonga_index');
--  pgroonga_table_name 
-- ---------------------
--  Sources17059
-- (1 row)

The old internal Groonga table exists until VACUUM:

SELECT pgroonga_command('object_exist',
                        ARRAY[
                          'name', :'old_pgroonga_table_name'
                        ])::json->>1;
--  ?column? 
-- ----------
--  true
-- (1 row)

You can remove the old internal Groonga table by pgroonga_vacuum():

SELECT pgroonga_vacuum();
--  pgroonga_vacuum 
-- -----------------
--  t
-- (1 row)
SELECT pgroonga_command('object_exist',
                        ARRAY[
                          'name', :'old_pgroonga_table_name'
                        ])::json->>1;
--  ?column? 
-- ----------
--  false
-- (1 row)