Hackers, I'm trying to write a query to give me a list of the columns and/or expressions in an index. For example, given this table:
david=# \d foo Table "public.foo" Column | Type | Modifiers ---------+-----------+----------- id | integer | bar_ids | integer[] | Indexes: "idx_foo_stuff" btree (id, abs(id), (bar_ids[1])) I'd like to write a query to emit: i | coalesce ---+--------------------- 0 | id 1 | abs(id) 2 | bar_ids[1] However, it looks as if I can only get multiple expressions as a single string. The query I've come up with is: SELECT s.i, COALESCE(a.attname, pg_catalog.pg_get_expr( x.indexprs, ct.oid )) FROM pg_catalog.pg_index x JOIN pg_catalog.pg_class ct ON ct.oid = x.indrelid JOIN pg_catalog.pg_class ci ON ci.oid = x.indexrelid JOIN pg_catalog.pg_namespace n ON n.oid = ct.relnamespace JOIN generate_series(0, current_setting('max_index_keys')::int - 1) s(i) ON x.indkey[s.i] IS NOT NULL LEFT JOIN pg_catalog.pg_attribute a ON ct.oid = a.attrelid AND a.attnum = x.indkey[s.i] WHERE ct.relname = 'foo' AND ci.relname = 'idx_foo_stuff' AND n.nspname = 'public' ORDER BY s.i; Which emits: i | coalesce ---+--------------------- 0 | id 1 | abs(id), bar_ids[1] 2 | abs(id), bar_ids[1] Is there some way to only get the relevant index expression from indexprs, rather than the whole expression? Thanks, David PS: I need this to work all the way back to 8.1, if possible. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers