This is a document for PGroonga 2.X. See PGroonga 1.x document when you're using old PGroonga.

pgroonga_wal_apply function

Summary

pgroonga_wal_apply function applies pending WAL. Normally, you don't need to use this function because PGroonga applies pending WAL automatically when INSERT, DELETE, UPDATE, SELECT and so on are executed.

Syntax

Here is the syntax of this function:

bitint pgroonga_wal_apply(pgroonga_index_name)

pgroonga_index_name is a text type value. It's a PGroonga index name to be applied pending WAL.

It returns the number of applied operations.

Here is another syntax of this function:

bigint pgroonga_wal_apply()

It applies pending WAL of all PGroonga indexes.

It returns the number of applied operations.

Usage

Here are sample schema and data:

SET pgroonga.enable_wal = yes;

CREATE TABLE memos (
  content text
);

CREATE INDEX pgroonga_memos_index
          ON memos
       USING pgroonga (content);

INSERT INTO memos VALUES ('PGroonga (PostgreSQL+Groonga) is great!');

Simulate PGroonga database is destroyed situation:

SELECT pgroonga_command('delete',
                        ARRAY[
                          'table', 'IndexStatuses',
                          'key', 'pgroonga_memos_index'::regclass::oid::text
                        ])::json->>1;
--  ?column? 
-- ----------
--  true
-- (1 row)
SELECT pgroonga_command('table_remove',
                        ARRAY[
                          'name', 'Lexicon' ||
                                  'pgroonga_memos_index'::regclass::oid ||
                                  '_0'
                        ])::json->>1;
--  ?column? 
-- ----------
--  true
-- (1 row)
SELECT pgroonga_command('table_remove',
                        ARRAY[
                          'name', pgroonga_table_name('pgroonga_memos_index')
                        ])::json->>1;
--  ?column? 
-- ----------
--  true
-- (1 row)

Now, there are pending WAL. You can apply the pending WAL explicitly:

SELECT pgroonga_wal_apply('pgroonga_memos_index');
--  pgroonga_wal_apply 
-- --------------------
--                   7
-- (1 row)

You can omit PGroonga index name. If you omit PGroonga index name, all pending WAL for all PGroonga indexes are applied explicitly:

SELECT pgroonga_wal_apply();
--  pgroonga_wal_apply 
-- --------------------
--                   7
-- (1 row)

See also