V3 protocol is slower than V2
Hi,
V3 protocol seems to be slower than V2 if we don't use prepared statement
together. I measured performance of protocols on 8.3beta using pgbench -S
with modification to use PQsendQueryParams and PQsendQueryPrepared
instead of PQsendQuery. (I'll send the patch to -patches shortly.)
[V2] PQsendQuery (V2; original)
[V3] PQsendQueryParams (V3)
[V3P] PQsendQueryPrepared (V3 with prepared statements)
V3 was 12% slower than V2, and V3P was 40% faster than V2.
There seems to be some inefficient behaviors in the handling of
V3 protocol or in libpq. Are there any TODO items here?
----
pg_ctl start -o "-c shared_buffers=1GB"
./pgbench -n -S -s50 -c16 -t100000 -M [V2|V3|PREPARE]
transaction type: SELECT only
scaling factor: 50
number of clients: 16
number of transactions per client: 100000
number of transactions actually processed: 1600000/1600000
sql mode: V2
tps = 19025.932203 (including connections establishing)
tps = 19036.285885 (excluding connections establishing)
sql mode: V3
tps = 16699.173521 (including connections establishing)
tps = 16707.135700 (excluding connections establishing)
sql mode: PREPARE
tps = 26629.710398 (including connections establishing)
tps = 26649.901658 (excluding connections establishing)
Regards,
---
ITAGAKI Takahiro
NTT Open Source Software Center
ITAGAKI Takahiro <itagaki.takahiro@oss.ntt.co.jp> writes:
[V2] PQsendQuery (V2; original)
[V3] PQsendQueryParams (V3)
[V3P] PQsendQueryPrepared (V3 with prepared statements)
V3 was 12% slower than V2, and V3P was 40% faster than V2.
Those aren't really comparable, because the functionality is different.
Did you check plain PQSendQuery on both V2 and V3?
regards, tom lane
Tom Lane <tgl@sss.pgh.pa.us> wrote:
ITAGAKI Takahiro <itagaki.takahiro@oss.ntt.co.jp> writes:
[V2] PQsendQuery (V2; original)
[V3] PQsendQueryParams (V3)
[V3P] PQsendQueryPrepared (V3 with prepared statements)V3 was 12% slower than V2, and V3P was 40% faster than V2.
Those aren't really comparable, because the functionality is different.
Did you check plain PQSendQuery on both V2 and V3?
Oops, I called 'simple query' V2. All of my tests used V3 protocol.
The results need to be read as:
PQsendQuery = (simple query)
vs.
PQsendQueryParams = (parse + bind + describe + execute + sync)
If the latter is slower than the former, the another version of
PQsendQueryParams, that fills parameters into SQL and uses simple-query,
might be considerable for performance. For example in Java, using
PreparedStatement class with V2 protocol.
Regards,
---
ITAGAKI Takahiro
NTT Open Source Software Center
Here is a patch for testing query modes on pgbench. It is discussed on
http://archives.postgresql.org/pgsql-hackers/2007-10/msg00755.php
I think this is useful to measure performance of protocols and
prepared statements. I hope the extended protocol will be improved
as fast as the simple protocol. It is 10-20% slower now.
(for 8.4 item)
The querymode option is added:
-M querymode
Choose the query mode from the follows:
simple: using simple query protocol.
extended: using extended protocol.
prepared: using extended protocol with prepared statements.
default is simple.
Usage:
$ pgbench -M [simple|extended|prepared]
Regards,
---
ITAGAKI Takahiro
NTT Open Source Software Center
Attachments:
pgbench_querymode.patchapplication/octet-stream; name=pgbench_querymode.patchDownload+206-74
This has been saved for the 8.4 release:
http://momjian.postgresql.org/cgi-bin/pgpatches_hold
---------------------------------------------------------------------------
ITAGAKI Takahiro wrote:
Here is a patch for testing query modes on pgbench. It is discussed on
http://archives.postgresql.org/pgsql-hackers/2007-10/msg00755.phpI think this is useful to measure performance of protocols and
prepared statements. I hope the extended protocol will be improved
as fast as the simple protocol. It is 10-20% slower now.
(for 8.4 item)The querymode option is added:
-M querymode
Choose the query mode from the follows:
simple: using simple query protocol.
extended: using extended protocol.
prepared: using extended protocol with prepared statements.
default is simple.Usage:
$ pgbench -M [simple|extended|prepared]Regards,
---
ITAGAKI Takahiro
NTT Open Source Software Center
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