Problem with indexing null values

There is a table 'test' with ~ 10M records with field 'finish'. select count(*) from test where finish is null; count --------- 2485009 (1 row) I'd like to create index to speed up queries like select * from test where finish is null; Just for testing purpose the following indexes were created: create index idx_t_0 on test(finish); create index idx_t_1 on test((finish is null)); create index idx_t_2 on test(id) where finish is null; gist=# set track_io_timing=on; [16/1920] SET gist=# EXPLAIN (ANALYZE, BUFFERS) select * from test where finish is null; QUERY PLAN ---------------------------------------------------------------------------------------------------------------------------- Seq Scan on test (cost=0.00..2829257.75 rows=2493440 width=1249) (actual time=0.031..23673.804 rows=2485009 loops=1) Filter: (finish IS NULL) Rows Removed by Filter: 6686627 Buffers: shared hit=129944 read=2606747 I/O Timings: read=15210.163 Planning time: 2.294 ms Execution time: 23847.759 ms (7 rows) gist=# set enable_seqscan=off; SET gist=# EXPLAIN (ANALYZE, BUFFERS) select * from test where finish is null; QUERY PLAN ---------------------------------------------------------------------------------------------------------------------------------- -------- Bitmap Heap Scan on test (cost=40312.83..2851483.71 rows=2493440 width=1249) (actual time=362.433..43436.427 rows=2485009 l oops=1) Recheck Cond: (finish IS NULL) Rows Removed by Index Recheck: 3622568 Heap Blocks: exact=14958 lossy=891618 Buffers: shared read=913368 I/O Timings: read=23970.878 -> Bitmap Index Scan on idx_t_2 (cost=0.00..39689.47 rows=2493440 width=0) (actual time=357.046..357.046 rows=2485009 loops=1 ) Buffers: shared read=6792 I/O Timings: read=50.203 Planning time: 0.256 ms Execution time: 43688.891 ms (11 rows) gist=# set enable_bitmapscan = off; SET gist=# EXPLAIN (ANALYZE, BUFFERS) select * from test where finish is null; QUERY PLAN ---------------------------------------------------------------------------------------------------------------------------------- ---------- Index Scan using idx_t_1 on test (cost=0.43..5670318.77 rows=2493440 width=1249) (actual time=2.049..14702.455 rows=2485009 loops=1) Index Cond: ((finish IS NULL) = true) Filter: (finish IS NULL) Buffers: shared read=913369 I/O Timings: read=9994.256 Planning time: 0.227 ms Execution time: 14875.190 ms (7 rows) **Config** listen_addresses ='*' port=5432 max_connections = 100 work_mem = 13107kB shared_buffers = 2GB effective_cache_size = 6GB maintenance_work_mem = 1GB # checkpoint_timeout = 300 # checkpoint_warning = 300 checkpoint_completion_target = 0.9 synchronous_commit = off default_statistics_target = 500 random_page_cost = 4 effective_io_concurrency = 2 wal_buffers = 16MB min_wal_size = 4GB max_wal_size = 8GB max_worker_processes = 4 max_parallel_workers_per_gather = 2 max_parallel_workers = 4 max_files_per_process=500