Обсуждение: 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