Re: Large tables, ORDER BY and sequence/index scans

>>>>> "PS" == Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:

PS> please EXPLAIN ANALYZE Pavel

I see, I'm sorry. Here are the results:

set enable_seqscan = on;
explain analyze declare c cursor for select * from foo2 order by value;
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------
Sort (cost=1829429.20..1854429.20 rows=9999999 width=10) (actual time=43432.727..49303.902 rows=9999999 loops=1)
Sort Key: value
Sort Method: external merge Disk: 204208kB
-> Seq Scan on foo2 (cost=0.00..154049.99 rows=9999999 width=10) (actual time=0.058..1775.928 rows=9999999 loops=1)
Total runtime: 53693.012 ms
(5 rows)

set enable_seqscan = off;
explain analyze declare c cursor for select * from foo2 order by value;

QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------------
Index Scan using foo2_value_idx on foo2 (cost=0.00..32220140.73 rows=9999999 width=10) (actual time=0.225..55055.583 rows=9999999 loops=1)
Total runtime: 56394.283 ms
(2 rows)