Re:

Looks like a Cartesian join to me. SELECT * FROM realisation r, post p

On Thu, Jun 2, 2016 at 6:42 PM, Max Lipsky <maxlipsky(at)gmail(dot)com> wrote:

> Sorry, I send broken link
> New link >> https://www.dropbox.com/s/8g3tkrikeap89q9/text.zip?dl=0
>
>
> On 03 Jun 2016, at 03:28, Steve Midgley <science(at)misuse(dot)org> wrote:
>
> In order to answer questions like that, generally, it's super helpful if
> you will include the "EXPLAIN" output for the query. It may also be useful
> to share some simple DDL stuff so we can create the tables and data you're
> using and try it out on our end.
>
> In this specific case (without digging too much into this, and without the
> info above) I'd guess there's an index missing and probably on the field "
> realisation_category_id"
>
> Steve
>
> On Thu, Jun 2, 2016 at 2:31 PM, Max Lipsky <maxlipsky(at)gmail(dot)com> wrote:
>
>> Hi All!
>>
>> Why is too much difference in time execution between these two queries:
>>
>>
>> SELECT rc.id AS id, rc.name
>> FROM realisation_category rc
>> WHERE EXISTS (
>> SELECT * FROM realisation r, post p WHERE (r.realisation_category_id
>> = rc.id AND r.site_id = 1)
>> OR (p.realisation_category_id = rc.id AND p.site_id = 1)
>> )
>> [2016-06-03 01:23:12] 35 row(s) retrieved starting from 1 in 14s 591ms
>> (14s 612ms total)
>>
>>
>>
>> SELECT rc.id AS id, rc.name
>> FROM realisation_category rc
>> WHERE EXISTS (
>> SELECT * FROM realisation r WHERE r.realisation_category_id = rc.id
>> AND r.site_id = 1
>> ) OR EXISTS (
>> SELECT * FROM post p WHERE p.realisation_category_id = rc.id AND
>> p.site_id = 1
>> )
>> [2016-06-03 01:25:25] 35 row(s) retrieved starting from 1 in 64ms (86ms
>> total)
>>
>> Thanks
>>
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>
>
>