plantuner module provides plantuner.forbid_index GUC which contains comma-separated list of indexes forbidden to use in query. USAGE (see sql/plantuner.sql: % LOAD 'plantuner'; % SET plantuner.forbid_index="i_idx, j_idx"; % SET enable_seqscan=off; % explain SELECT * FROM wow; QUERY PLAN -------------------------------------------------------------------------- Seq Scan on wow (cost=10000000000.00..10000000031.40 rows=2140 width=8) It's recommended to load library by shared_preload_libraries option in postgresql.conf