Re: [HACKERS] [PATCHES] Last infomask bit
Tom Lane wrote: Bruce Momjian <[EMAIL PROTECTED]> writes: Tom Lane wrote: Has anyone bothered to measure the overhead added by having to mask to fetch or store the natts value? This is not a zero-cost improvement. Tom, how should this be tested? I assume some loop of the same query over and over again. I'd be satisfied by a demonstration of no meaningful difference in pgbench numbers. I ran pgbench on CVS checkout taken before the patch was applied, and I couldn't measure a difference. I got 1329-1340 TPM from three runs both with and without the patch. The tests were run on my laptop, with scaling factor 10, using "pgbench postgres -t 10 -v", with fsync and full_page_writes disabled to make it CPU bound, while observing top to confirm that CPU usage was 100% during the test. I think that's enough performance testing for this patch. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com ---(end of broadcast)--- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
Re: [HACKERS] [PATCHES] Last infomask bit
Heikki Linnakangas wrote: > Bruce Momjian wrote: > > Tom Lane wrote: > >> Bruce Momjian <[EMAIL PROTECTED]> writes: > >>> Patch applied. Thanks. > >>> I added a comment about the unused bits in the header file. > >> Has anyone bothered to measure the overhead added by having to mask to > >> fetch or store the natts value? This is not a zero-cost improvement. > > > > SHOW ALL has: > > > >log_temp_files | -1 | Log > > the use of temporary files larger than th > > > > and pg_settings has: > > > >log_temp_files| -1 | kB | Reporting and Logging / What to Log > > > > Looks OK to me. > > What? I'm completely lost here. What does log_temp_files have to do with > the bits on the tuple header? Sorry, Tom wanted two things tested and I replied to the wrong email. -- Bruce Momjian [EMAIL PROTECTED] EnterpriseDBhttp://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---(end of broadcast)--- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate
Re: [pgsql-patches] [HACKERS] [PATCHES] Last infomask bit
Heikki Linnakangas <[EMAIL PROTECTED]> writes: > What? I'm completely lost here. What does log_temp_files have to do with > the bits on the tuple header? Nothing, it looks like Bruce replied to the wrong message at one point while these two threads were active ... regards, tom lane ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster
Re: [HACKERS] [PATCHES] Last infomask bit
Tom Lane wrote: Bruce Momjian <[EMAIL PROTECTED]> writes: Tom Lane wrote: Has anyone bothered to measure the overhead added by having to mask to fetch or store the natts value? This is not a zero-cost improvement. I haven't tested it. Agreed, it does add an AND operation to places where t_natts is accessed. Tom, how should this be tested? I assume some loop of the same query over and over again. I'd be satisfied by a demonstration of no meaningful difference in pgbench numbers. It's *probably* not a problem, but you never know if you don't check... I doubt there's any measurable difference, but I can do a pgbench run to make sure. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com ---(end of broadcast)--- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
Re: [HACKERS] [PATCHES] Last infomask bit
Bruce Momjian wrote: Tom Lane wrote: Bruce Momjian <[EMAIL PROTECTED]> writes: Patch applied. Thanks. I added a comment about the unused bits in the header file. Has anyone bothered to measure the overhead added by having to mask to fetch or store the natts value? This is not a zero-cost improvement. SHOW ALL has: log_temp_files | -1 | Log the use of temporary files larger than th and pg_settings has: log_temp_files| -1 | kB | Reporting and Logging / What to Log Looks OK to me. What? I'm completely lost here. What does log_temp_files have to do with the bits on the tuple header? -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster
Re: [HACKERS] [PATCHES] Last infomask bit
Tom Lane wrote: > Bruce Momjian <[EMAIL PROTECTED]> writes: > > > SHOW ALL has: > > >log_temp_files | -1 | Log > > the use of temporary files larger than th > > Yeah, but if you do "SET log_temp_files = -1", does it still say that? > I'm worried that will change it to -1024. You can rest easy tonight. :-) test=> SET log_temp_files = -1; SET test=> SHOW log_temp_files; log_temp_files -1 (1 row) test=> SET log_temp_files = 1; SET test=> SHOW log_temp_files; log_temp_files 1kB (1 row) -- Bruce Momjian [EMAIL PROTECTED] EnterpriseDBhttp://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---(end of broadcast)--- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
Re: [HACKERS] [PATCHES] Last infomask bit
Bruce Momjian <[EMAIL PROTECTED]> writes: > Tom Lane wrote: >> Has anyone bothered to measure the overhead added by having to mask to >> fetch or store the natts value? This is not a zero-cost improvement. > Tom, how should this be tested? I assume some loop of the same query > over and over again. I'd be satisfied by a demonstration of no meaningful difference in pgbench numbers. It's *probably* not a problem, but you never know if you don't check... regards, tom lane ---(end of broadcast)--- TIP 4: Have you searched our list archives? http://archives.postgresql.org
Re: [HACKERS] [PATCHES] Last infomask bit
Bruce Momjian <[EMAIL PROTECTED]> writes: > SHOW ALL has: >log_temp_files | -1 | Log the > use of temporary files larger than th Yeah, but if you do "SET log_temp_files = -1", does it still say that? I'm worried that will change it to -1024. regards, tom lane ---(end of broadcast)--- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate
Re: [HACKERS] [PATCHES] Last infomask bit
Tom Lane wrote: > Bruce Momjian <[EMAIL PROTECTED]> writes: > > Patch applied. Thanks. > > I added a comment about the unused bits in the header file. > > Has anyone bothered to measure the overhead added by having to mask to > fetch or store the natts value? This is not a zero-cost improvement. SHOW ALL has: log_temp_files | -1 | Log the use of temporary files larger than th and pg_settings has: log_temp_files| -1 | kB | Reporting and Logging / What to Log Looks OK to me. -- Bruce Momjian [EMAIL PROTECTED] EnterpriseDBhttp://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---(end of broadcast)--- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate
Re: [HACKERS] [PATCHES] Last infomask bit
Tom Lane wrote: > Bruce Momjian <[EMAIL PROTECTED]> writes: > > Patch applied. Thanks. > > I added a comment about the unused bits in the header file. > > Has anyone bothered to measure the overhead added by having to mask to > fetch or store the natts value? This is not a zero-cost improvement. I assumed Heikki had tested it, but now see no mention of a test in the posting: http://archives.postgresql.org/pgsql-patches/2007-01/msg00052.php Tom, how should this be tested? I assume some loop of the same query over and over again. -- Bruce Momjian [EMAIL PROTECTED] EnterpriseDBhttp://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---(end of broadcast)--- TIP 6: explain analyze is your friend
Re: [HACKERS] [PATCHES] Last infomask bit
Bruce Momjian <[EMAIL PROTECTED]> writes: > Patch applied. Thanks. > I added a comment about the unused bits in the header file. Has anyone bothered to measure the overhead added by having to mask to fetch or store the natts value? This is not a zero-cost improvement. regards, tom lane ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster
Re: [HACKERS] [PATCHES] Last infomask bit
Heikki Linnakangas <[EMAIL PROTECTED]> writes: > I believe it would actually be even better to combine the t_natts and > t_infomask fields to a single 32-bit infomask field. That's not happening, because the alignment is wrong ...unless maybe we switch this field to fall before t_ctid, but that would screw up the MinimalTuple hack. regards, tom lane ---(end of broadcast)--- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
