Обсуждение: EXPLAIN

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EXPLAIN

От
Andy
Дата:
 When I do an explain what does the cost, size and width mean that is returned?

 Seq Scan on apts  (cost=249.95 size=2362 width=468)

 Thanks

 Andy


Re: [GENERAL] EXPLAIN

От
Bruce Momjian
Дата:
>  When I do an explain what does the cost, size and width mean that is returned?
>
>  Seq Scan on apts  (cost=249.95 size=2362 width=468)

Cost is a computed value by the optimizer of how long it will execute.
It is meaningful only in comparison to there queries.  size if the
number of rows estimated to return.  width is the number of bytes per
row returned.


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