Horton

Re: sortsupport for text

Greg Stark <stark@mit.edu>

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From: Greg Stark <stark@mit.edu>
To: Robert Haas <robertmhaas@gmail.com>
Cc: pgsql-hackers@postgresql.org
Date: 2012-03-17T22:58:33Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Adjust string comparison so that only bitwise-equal strings are considered

  2. Add operator strategy and comparison-value datatype fields to ScanKey.

On Fri, Mar 2, 2012 at 8:45 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> 12789    28.2686  libc-2.13.so             strcoll_l
> 6802     15.0350  postgres                 text_cmp

I'm still curious how it would compare to call strxfrm and sort the
resulting binary blobs. I don't think the sortsupport stuff actually
makes this any easier though. Since using it requires storing the
binary blob somewhere I think the support would have to be baked into
tuplesort (or hacked into the sortkey as an expr that was evaluated
earlier somehow).

It's a tradeoff and not an obvious one. The binary blobs are larger
and it would mean reading and copying more data around memory. But it
would mean doing the work that strcoll_l does only n times instead of
nlogn times. That might be a pretty significant gain.

-- 
greg