How can I drop all indexes of a table in Postgres?

问题:

I keep having this problem: I have like 20 indexes on a table that I need to drop in order to do testing. Dropping the table doesn't drop all of this metadata.

There doesn't seem to be a wildcard drop index ix_table_* or any useful command. There seem to be some bash loops around psql you can write.
There must be something better! Thoughts?

回答1:

Assuming you only want to drop plain indexes:

DO
$$BEGIN
   EXECUTE (
   SELECT 'DROP INDEX ' || string_agg(indexrelid::regclass::text, ', ')
   FROM   pg_index  i
   LEFT   JOIN pg_depend d ON d.objid = i.indexrelid
                          AND d.deptype = 'i'
   WHERE  i.indrelid = 'your_table_name_here'::regclass  -- possibly schema-qualified
   AND    d.objid IS NULL                                -- no internal dependency
   );
END$$;

Does not touch indexes created as implementation detail of constraints (UNIQUE, PK, EXCLUDE).
The documentation:

DEPENDENCY_INTERNAL (i)

The dependent object was created as part of creation of the referenced object, and is really just a part of its internal implementation.

You could wrap this in a function for repeated execution.
Related:

• Table name as a PostgreSQL function parameter

---

Aside: This is a misunderstanding:

Dropping the table doesn't drop all of this metadata.

Dropping a table always cascades to all indexes on the table.

回答2:

This is how I remove all indexes from postgres, excluding all pkey.

CREATE OR REPLACE FUNCTION drop_all_indexes() RETURNS INTEGER AS $$
DECLARE
  i RECORD;
BEGIN
  FOR i IN 
    (SELECT relname FROM pg_class
       -- exclude all pkey, exclude system catalog which starts with 'pg_'
      WHERE relkind = 'i' AND relname NOT LIKE '%_pkey%' AND relname NOT LIKE 'pg_%')
  LOOP
    -- RAISE INFO 'DROPING INDEX: %', i.relname;
    EXECUTE 'DROP INDEX ' || i.relname;
  END LOOP;
RETURN 1;
END;
$$ LANGUAGE plpgsql;

To execute:

SELECT drop_all_indexes();

Before actually executing 'DROP INDEX xxx', I would comment out the line 'EXECUTE ...' using '-- ', and uncomment the 'RAISE INFO' line, run it with 'select func_name();' and double check I'm not dropping something I should not.

For our application, we have all schema statements including indexes creation in one file app.sql. Before this whole project goes to production, we want to clean up all historically created indexes, then recreate them using:

psql -f /path/to/app.sql

Hope this helps.

回答3:

The query below drops all user indexes which are not related with any constraint (primary key, unique key)

SELECT
    format('DROP INDEX %I.%I;', n.nspname, c_ind.relname)
  FROM pg_index ind
  JOIN pg_class c_ind ON c_ind.oid = ind.indexrelid
  JOIN pg_namespace n ON n.oid = c_ind.relnamespace
  LEFT JOIN pg_constraint cons ON cons.conindid = ind.indexrelid
  WHERE
    n.nspname NOT IN ('pg_catalog','information_schema') AND 
    n.nspname !~ '^pg_toast'::TEXT AND
    cons.oid IS NULL

You can use \gexec meta-command feature of psql to execute statement