| From: | Tom Mercha <mercha_t(at)hotmail(dot)com> |
|---|---|
| To: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> |
| Cc: | "pgsql-general(at)lists(dot)postgresql(dot)org" <pgsql-general(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Measuring the Query Optimizer Effect: Turning off the QO? |
| Date: | 2019-07-08 19:20:25 |
| Message-ID: | AM6PR04MB55445BB12D563CE72A426295F4F60@AM6PR04MB5544.eurprd04.prod.outlook.com |
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| Lists: | pgsql-general |
On 08/07/2019 16:23, Andrew Gierth wrote:
>>>>>> "Tom" == Tom Mercha <mercha_t(at)hotmail(dot)com> writes:
>
> Tom> Hi All
>
> Tom> As we know, a query goes through number of stages before it is
> Tom> executed. One of these stages is query optimization (QO).
>
> That's not really true at all. One of the stages is query _planning_,
> which takes the (rewritten) query as input and converts it to something
> that the executor can take action on. There isn't actually any separate
> "optimization" phase.
>
Hi
I was just loosely speaking - I am merely referring to the concept that
a query can be optimized vs unoptimized. Of course it follows that we
have a phase or a subset of stages which are responsible for this purpose.
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