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help / color / mirror / Atom feedFrom: David G. Johnston <[email protected]>
To: Zach Aysan <[email protected]>
Cc: Pg Docs <[email protected]>
Subject: Re: Reverse btree indexes
Date: Tue, 22 Jun 2021 15:51:23 -0700
Message-ID: <CAKFQuwYsDe8gVLL66oSDKbDZ6Ln72ygDp=R2CPfd7Ri7acRPkg@mail.gmail.com> (raw)
In-Reply-To: <CABYkO2Bfg6sJviiOCBze0fJ5720Oo3VjRnVtVNKM-0i0exALVg@mail.gmail.com>
References: <CABYkO2Bfg6sJviiOCBze0fJ5720Oo3VjRnVtVNKM-0i0exALVg@mail.gmail.com>
On Tue, Jun 22, 2021 at 2:28 PM Zach Aysan <[email protected]> wrote:
> *Desired improvement:*
>
> for example, col LIKE 'foo%' or col ~ '^foo', but not col LIKE '%bar',
>> which would require a reversed index on the field. Postgres will
>> automatically use the reverse index for LIKE '%bar'
>
>
> *Or if it doesn't:*
>
It doesn't, otherwise the documentation wouldn't need to point out: but not
col LIKE '%bar' ...
>
>> for example, col LIKE 'foo%' or col ~ '^foo', but not col LIKE '%bar',
>> which would require a reversed index on the field. To use the reversed
>> index, query with reverse(col) like reverse('%bar').
>
>
>
This type of commentary isn't usually something we include in the
documentation...and I'm not too keen on "reversed index" as a phrase
regardless.
David J.
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Subject: Re: Reverse btree indexes
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