From: | Vincenzo Romano <vincenzo(dot)romano(at)notorand(dot)it> |
---|---|
To: | Merlin Moncure <mmoncure(at)gmail(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Composite types questions |
Date: | 2010-01-11 18:21:07 |
Message-ID: | 3eff28921001111021k5ab79f54ufe47496cb7031db3@mail.gmail.com |
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Lists: | pgsql-general |
2010/1/11 Merlin Moncure <mmoncure(at)gmail(dot)com>:
> On Mon, Jan 11, 2010 at 11:08 AM, Vincenzo Romano > SELECT * FROM master_tab
>> WHERE col1>='a date':timestamp AND col1<'another date'::timestamp
>> AND col2=42 AND col3='the answer';
>
> queries of this sort are optimally handled via row constructor for 8.2 onwards:
>
> create index col231_idx on master_tab(col2, col3, col1);
>
> select * from master_tab where (col2,col3,co1) >= (42, 'the answer',
> a_date) and (col2,col3,co1) < (42, 'the answer', b_date);
>
> one caveat: the planner is lousy in regards to estimating index
> selectivity in these cases which can cause strange behaviors.
>
> regarding constraint_exclusion, I don't think there are any
> issues...you should test it to be sure.
>
> merlin
>
Great news for me!
Thanks Merlin ... the Wizard! :-)
--
Vincenzo Romano
NotOrAnd Information Technologies
cel. +39 339 8083886 | gtalk. vincenzo(dot)romano(at)notorand(dot)it
fix. +39 0823 454163 | skype. notorand.it
fax. +39 02 700506964 | msn. notorand.it
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