Horton

Re: SendRowDescriptionMessage() is slow for queries with a lot of columns

tushar <tushar.ahuja@enterprisedb.com>

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From: tushar <tushar.ahuja@enterprisedb.com>
To: Andres Freund <andres@anarazel.de>, pgsql-hackers@postgresql.org
Date: 2017-09-29T09:02:30Z
Lists: pgsql-hackers 
On 09/27/2017 10:50 PM, Andres Freund wrote:
> This'll allow the later patches to allow the compiler to perform the
> relevant optimizations. It also allows to optimize e.g. pq_sendint64()
> to avoid having to do multiple byteswaps.

After applying all the required patches, able to see some performance gain

Virtual Machine configuration - Centos 6.5 x64 / 16 GB RAM / 8 VCPU core 
processor

./pgbench -M prepared -j 10 -c 10 -f /tmp/pgbench-many-cols.sql postgres 
-T TIME

After taking Median of 3 run  -

Case 1 – TIME=300

PG HEAD =>41285.089261 (excluding connections establishing)
PG HEAD+patch =>tps= 42446.626947(2.81+% vs. head)

Case 2- TIME=500

PG HEAD =>tps = 41252.897670 (excluding connections establishing)
PG HEAD+patch =>tps= 42257.439550(2.43+% vs. head)

Case 3- TIME=1000

PG HEAD =>tps = 1061.031463 (excluding connections establishing)
PG HEAD+patch => tps= 8011.784839(3.30+% vs. head)

Case 4-TIME=1500

PG HEAD =>tps = 40365.099628 (excluding connections establishing)
PG HEAD+patch =>tps= 42385.372848(5.00+% vs. head)

-- 
regards,tushar
EnterpriseDB  https://www.enterprisedb.com/
The Enterprise PostgreSQL Company

Commits

  1. Replace remaining uses of pq_sendint with pq_sendint{8,16,32}.

  2. Improve performance of SendRowDescriptionMessage.

  3. Use one stringbuffer for all rows printed in printtup.c.

  4. Add configure infrastructure to detect support for C99's restrict.

  5. Add more efficient functions to pqformat API.

  6. Allow to avoid NUL-byte management for stringinfos and use in format.c.

  7. Replace most usages of ntoh[ls] and hton[sl] with pg_bswap.h.

  8. Extend & revamp pg_bswap.h infrastructure.