Horton

Re: reducing the footprint of ScanKeyword (was Re: Large writable variables)

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Andrew Gierth <andrew@tao11.riddles.org.uk>, John Naylor <jcnaylor@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2018-12-26T18:04:35Z
Lists: pgsql-hackers 
Hi,

On 2018-12-26 10:45:11 -0500, Robert Haas wrote:
> I'm not sure that I understand quite what you have in mind for a
> serialized non-perfect hashtable.  Are you thinking that we'd just
> construct a simplehash and serialize it?

I was basically thinking that we'd have the perl script implement a
simple hash and put the keyword (pointers) into an array, handling
conflicts with the simplest linear probing thinkable. As there's never a
need for modifications, that ought to be fairly simple.

Greetings,

Andres Freund

Commits

  1. Use perfect hashing, instead of binary search, for keyword lookup.

  2. Reduce the size of the fmgr_builtin_oid_index[] array.

  3. Replace the data structure used for keyword lookup.