CREATE UNIQUE INDEX IF NOT EXISTS in postgreSQL

Question

Plese I would like to do in PostgreSQL something like

CREATE UNIQUE INDEX IF NOT EXISTS

Any idea?

Answer 1

You can check, if an index with a given name exists with this statement.

If your index name is some_table_some_field_idx

SELECT count(*) > 0
FROM pg_class c
WHERE c.relname = 'some_table_some_field_idx' 
AND c.relkind = 'i';

Starting from Postgres 9.5 you can even use

CREATE INDEX IF NOT EXISTS

Answer 2

Just another ready-to-use solution.

PostgreSQL v9.0+:

DO $BLOCK$
BEGIN
    BEGIN
        CREATE INDEX index_name ON table_name( column_name );
    EXCEPTION
        WHEN duplicate_table
        THEN RAISE NOTICE 'index ''index_name '' on table_name already exists, skipping';
    END;
END;
$BLOCK$;

PostgreSQL v9.5+:

CREATE INDEX IF NOT EXISTS index_name ON table_name( column_name );