From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | David Johnston <polobo(at)yahoo(dot)com> |
Cc: | John R Pierce <pierce(at)hogranch(dot)com>, "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Difference between varchar and text? |
Date: | 2012-11-18 07:29:56 |
Message-ID: | 23648.1353223796@sss.pgh.pa.us |
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Lists: | pgsql-general |
David Johnston <polobo(at)yahoo(dot)com> writes:
> On Nov 17, 2012, at 20:43, John R Pierce <pierce(at)hogranch(dot)com> wrote:
>> I think he meant a tiny tiny bit faster, primarily due to not having to validate the length.
> Maybe... But I would presume a "varchar with no limit" does not validate length...
There is overhead from the type system for varchar, whether or not it
has a length limit --- you'll get at least some RelabelType nodes in
expression trees, and those don't have zero cost to execute.
I'd generally recommend using "text" if you don't have any interest in
enforcing a specific length limit.
regards, tom lane
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