Combining indexes

Though, this doesn't mean the v index is useless. If you are running something that is selective based on the k index, the one on v can be combined with that. With the index in place, this earlier example now uses a complicated query plan:

EXPLAIN ANALYZE SELECT count(*) FROM t WHERE k>9000 AND v=5;
QUERY PLAN                                                        
-------------------------
Aggregate  (cost=787.97..787.98 rows=1 width=0) (actual time=40.545..40.546 rows=1 loops=1)
   ->  Bitmap Heap Scan on t  (cost=170.38..765.03 rows=9176 width=0) (actual time=4.107..24.606 rows=9097 loops=1)
         Recheck Cond: (v = 5)
         Filter: (k > 9000)
         ->  Bitmap Index Scan on i  (cost=0.00..168.08 rows=10110 width=0) (actual time=3.255..3.255 rows=9993 loops=1)
               Index Cond: (v = 5)
 Total runtime: 40.638 ms

seq_scan       | 0
seq_tup_read   | 0
idx_scan       | 1
idx_tup_fetch  | 9993
heap_blks_read | 0
heap_blks_hit  | 443...