From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
Cc: | Teodor Sigaev <teodor(at)sigaev(dot)ru>, Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: jsonb access operators inefficiency |
Date: | 2014-05-30 17:41:56 |
Message-ID: | 6302.1401471716@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
> If we're going to construct varlena objects inside a StringInfo, maybe
> we need a proper API for it. Isn't there a danger that data member of
> the StringInfo won't be properly aligned to allow us to do this? In any
> case, we should get most of the benefit of your patch without this
> "optimization".
As noted, the data buffer is maxaligned; but nonetheless I agree that
this is a serious stylistic abuse, and it's not buying much compared
to the rest of the patch. I'd stick with the cstring_to_text_with_len
coding.
At the other end of the process, why are we using PG_GETARG_TEXT_P
and not PG_GETARG_TEXT_PP to avoid a "detoast" cycle on short-header
inputs? The function body is using VARDATA_ANY/VARSIZE_ANY_EXHDR,
so it's already prepared for unaligned input.
regards, tom lane
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