pgroonga.table_name function

Summary

pgroonga.table_name function converts PGroonga index name to Groonga table name. Groonga table name is useful select Groonga command by pgroonga.command function.

You can use weight feature by select Groonga command.

Syntax

Here is the syntax of this function:

text pgroonga.table_name(pgroonga_index_name)

pgroonga_index_name is a text type value. It's an index name to be converted to Groonga table name. The index should be created with USING pgroonga.

pgroonga.table_name returns Groonga table name for pgroonga_index_name as text type value. If pgroonga_index_name doesn't exist or isn't a PGroonga index, pgroonga.table_name raises an error.

Usage

Here are sample schema and data. In the schema, both search target data and output data are index target columns:

CREATE TABLE terms (
  id integer,
  title text,
  content text,
  tag varchar(256)
);

CREATE INDEX pgroonga_terms_index
          ON terms
       USING pgroonga (title, content, tag);

INSERT INTO terms
     VALUES (1,
             'PostgreSQL',
             'PostgreSQL is a relational database management system.',
             'PostgreSQL');
INSERT INTO terms
     VALUES (2,
             'Groonga',
             'Groonga is a fast full text search engine that supports all languages.',
             'Groonga');
INSERT INTO terms
     VALUES (3,
             'PGroonga',
             'PGroonga is a PostgreSQL extension that uses Groonga as index.',
             'PostgreSQL');

You can use match_columns option to use weight:

SELECT *
  FROM json_array_elements(
         pgroonga.command('select ' ||
                          pgroonga.table_name('pgroonga_terms_index') || ' ' ||
                          '--match_columns "title * 10 || content" ' ||
                          '--query "Groonga OR PostgreSQL OR engine" ' ||
                          '--output_columns "_score, title, content" ' ||
                          '--sortby "-_score"'
                         )::json->1->0);
--                                           value                                          
-- -----------------------------------------------------------------------------------------
--  [3]
--  [["_score","Int32"],["title","LongText"],["content","LongText"]]
--  [12,"Groonga","Groonga is a fast full text search engine that supports all languages."]
--  [11,"PostgreSQL","PostgreSQL is a relational database management system."]
--  [2,"PGroonga","PGroonga is a PostgreSQL extension that uses Groonga as index."]
-- (5 rows)

You can use drilldown feature by drilldown option:

SELECT *
  FROM json_array_elements(
         pgroonga.command('select ' ||
                          pgroonga.table_name('pgroonga_terms_index') || ' ' ||
                          '--match_columns "title * 10 || content" ' ||
                          '--query "Groonga OR PostgreSQL OR engine" ' ||
                          '--output_columns "_score, title" ' ||
                          '--sortby "-_score" ' ||
                          '--drilldown "tag"'
                         )::json->1);
--                                               value                                              
-- -------------------------------------------------------------------------------------------------
--  [[3],[["_score","Int32"],["title","LongText"]],[12,"Groonga"],[11,"PostgreSQL"],[2,"PGroonga"]]
--  [[2],[["_key","ShortText"],["_nsubrecs","Int32"]],["Groonga",1],["PostgreSQL",2]]
-- (2 rows)

select Groonga command may help you when SELECT statement in SQL is slow.

See also