Horton

Re: pgbench - add pseudo-random permutation function

Alvaro Herrera <alvherre@2ndquadrant.com>

View thread
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Thomas Munro <thomas.munro@gmail.com>
Cc: Fabien COELHO <coelho@cri.ensmp.fr>, David Steele <david@pgmasters.net>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Hironobu SUZUKI <hironobu@interdb.jp>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-03-12T21:12:22Z
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. pgbench: Function to generate random permutations.

  2. Add basic support for using the POPCNT and SSE4.2s LZCNT opcodes

  3. Further improve code for probing the availability of ARM CRC instructions.

On 2021-Mar-13, Thomas Munro wrote:

> That doesn't sound like a bad option to me, if it makes this much
> simpler.  The main modern system without it seems to be MSVC.  The
> Linux, BSD, Apple, illumos, AIX systems using Clang/GCC with
> Intel/AMD/ARM/PowerPC CPUs have it, and the Windows systems using open
> source compilers have it.

Hmm.  Can we go a bit further, and say that if you don't have 128-bit
ints, then you can use pr_perm but only to a maximum of 32-bit ints?
Then you can do the calculations in 64-bit ints.  That's much less bad
than desupporting the feature altogether.

-- 
Álvaro Herrera                            39°49'30"S 73°17'W
"No necesitamos banderas
 No reconocemos fronteras"                  (Jorge González)