Explain

Hi,

when I do an explain on a certain query, I have this answer :


                                      QUERY PLAN
--------------------------------------------------------------------------------------
 Aggregate  (cost=100017927.48..100017927.48 rows=1 width=8)
   ->  Seq Scan on stats_daily_2003
(cost=100000000.00..100017927.47 rows=1 width=8)
         Filter: ((id_compte = 29075) AND (periode = '07-07-2003'::date))
(3 rows)


Well, I don"t really undestand the meaning of

cost=100000000.00..100017927.47

and

cost=100017927.48..100017927.48

I guess this result is relatively bad.

The same query on a similar table but with an index give :

                                                 QUERY PLAN
--------------------------------------------------------------------------------------------
----------------
 Aggregate  (cost=9.60..9.60 rows=1 width=8)
   ->  Index Scan using ap_stats_daily_2003_save on
stats_daily_2003_save  (cost=0.00..9.59 rows=2 width=8)
         Index Cond: ((periode = '07-07-2003'::date) AND (id_compte =
29075))
(3 rows)

Could you confirm me the second explain is "better" than the first one
?





Jean-Arthur Silve
EuroVox
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