From: Tom Lane <tgl@sss.pgh.pa.us>
To: Loles <lolesft@gmail.com>
Cc: pgsql-admin@postgresql.org
Subject: Re: Optimized WHERE UPPER(name) LIKE UPPER('%p_name%')
Date: Mon, 30 Oct 2023 10:08:20 -0400
Message-ID: <2400807.1698674900@sss.pgh.pa.us> (raw)
In-Reply-To: <CA+FWGK480H3mRVsSy0xofYhvpx9W1Y_h6nGfoOh0tuE0ecJ45g@mail.gmail.com>
References: <CA+FWGK480H3mRVsSy0xofYhvpx9W1Y_h6nGfoOh0tuE0ecJ45g@mail.gmail.com>
Loles <lolesft@gmail.com> writes:
> We have seen performance down when we use WHERE UPPER(name) LIKE
> UPPER('%Alice%') in the condition.
> If we compare with WHERE UPPER(name) = UPPER('Alice') it runs very fast.
Presumably, that works well because you have a btree index on UPPER(name).
But btree can't optimize a pattern with a leading '%' --- see
https://www.postgresql.org/docs/current/indexes-types.html#INDEXES-TYPES-BTREE
You could possibly use a pg_trgm index instead, see
https://www.postgresql.org/docs/current/pgtrgm.html
The performance properties will be somewhat different from btree,
but it might get the job done.
regards, tom lane
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To: pgsql-admin@postgresql.org
Cc: tgl@sss.pgh.pa.us, lolesft@gmail.com
Subject: Re: Optimized WHERE UPPER(name) LIKE UPPER('%p_name%')
In-Reply-To: <2400807.1698674900@sss.pgh.pa.us>
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