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Re: Seq Scan

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Ok, my bad.
But why this happens:
# explain ANALYZE select id from table_name where id>200000;
                                                                QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------
Index Scan using table_name_pkey on table_name  (cost=0.00..2618.96
rows=68960 width=4) (actual time=220.543..1479.495 rows=66730 loops=1)
  Index Cond: (id > 200000)
Total runtime: 1504.839 ms
(3 rows)

dun=# explain ANALYZE select id from table_name where id>10;
                                                     QUERY PLAN
----------------------------------------------------------------------------------------------------------------------
Seq Scan on table_name  (cost=0.00..9268.12 rows=266703 width=4)
(actual time=107.935..2733.592 rows=266720 loops=1)
  Filter: (id > 10)
Total runtime: 2833.744 ms
(3 rows)


It uses Index Scan for id>200000 and Seq Scan for id>10?!

On 6/1/07, Joshua D. Drake <jd@xxxxxxxxxxxxxxxxx> wrote:

Nothing. You have to scan the table because you aren't giving postgresql
anything to use the index by.

Joshua D. Drake



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