Re: [Proposal] Global temporary tables
"曾文旌(义从)" <[email protected]> Tue, 14 Jan 2020 21:09:34 +0800
| Newsgroups | gmane.comp.db.postgresql.devel.general |
|---|---|
| Message-ID | <[email protected]> |
--Apple-Mail=_56A6B3F9-3268-444C-9A38-9CE6B6557497 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Thank you for review my patch. > 2020=E5=B9=B41=E6=9C=8812=E6=97=A5 =E4=B8=8A=E5=8D=884:27=EF=BC=8CPavel = Stehule <[email protected]> =E5=86=99=E9=81=93=EF=BC=9A >=20 > Hi >=20 > so 11. 1. 2020 v 15:00 odes=C3=ADlatel =E6=9B=BE=E6=96=87=E6=97=8C(=E4=B9= =89=E4=BB=8E) <[email protected] = <mailto:[email protected]>> napsal: > Hi all >=20 > This is the latest patch >=20 > The updates are as follows: > 1. Support global temp Inherit table global temp partition table > 2. Support serial column in GTT > 3. Provide views pg_gtt_relstats pg_gtt_stats for GTT=E2=80=99s = statistics > 4. Provide view pg_gtt_attached_pids to manage GTT > 5. Provide function pg_list_gtt_relfrozenxids() to manage GTT > 6. Alter GTT or rename GTT is allowed under some conditions >=20 >=20 > Please give me feedback. >=20 > I tested the functionality >=20 > 1. i think so "ON COMMIT PRESERVE ROWS" should be default mode (like = local temp tables). makes sense, I will fix it. >=20 > I tested some simple scripts=20 >=20 > test01.sql >=20 > CREATE TEMP TABLE foo(a int, b int); > INSERT INTO foo SELECT random()*100, random()*1000 FROM = generate_series(1,1000); > ANALYZE foo; > SELECT sum(a), sum(b) FROM foo; > DROP TABLE foo; -- simulate disconnect >=20 >=20 > after 100 sec, the table pg_attribute has 3.2MB > and 64 tps, 6446 transaction >=20 > test02.sql >=20 > INSERT INTO foo SELECT random()*100, random()*1000 FROM = generate_series(1,1000); > ANALYZE foo; > SELECT sum(a), sum(b) FROM foo; > DELETE FROM foo; -- simulate disconnect >=20 >=20 > after 100 sec, 1688 tps, 168830 transactions >=20 > So performance is absolutely different as we expected. >=20 > =46rom my perspective, this functionality is great. Yes, frequent ddl causes catalog bloat, GTT avoids this problem. >=20 > Todo: >=20 > pg_table_size function doesn't work Do you mean that function pg_table_size() need get the storage space = used by the one GTT in the entire db(include all session) . >=20 > Regards >=20 > Pavel >=20 >=20 > Wenjing >=20 >=20 >=20 >=20 >=20 >> 2020=E5=B9=B41=E6=9C=886=E6=97=A5 =E4=B8=8A=E5=8D=884:06=EF=BC=8CTomas = Vondra <[email protected] = <mailto:[email protected]>> =E5=86=99=E9=81=93=EF=BC=9A >>=20 >> Hi, >>=20 >> I think we need to do something with having two patches aiming to add >> global temporary tables: >>=20 >> [1] https://commitfest.postgresql.org/26/2349/ = <https://commitfest.postgresql.org/26/2349/> >>=20 >> [2] https://commitfest.postgresql.org/26/2233/ = <https://commitfest.postgresql.org/26/2233/> >>=20 >> As a reviewer I have no idea which of the threads to look at - = certainly >> not without reading both threads, which I doubt anyone will really = do. >> The reviews and discussions are somewhat intermixed between those two >> threads, which makes it even more confusing. >>=20 >> I think we should agree on a minimal patch combining the = necessary/good >> bits from the various patches, and terminate one of the threads (i.e. >> mark it as rejected or RWF). And we need to do that now, otherwise >> there's about 0% chance of getting this into v13. >>=20 >> In general, I agree with the sentiment Rober expressed in [1] - the >> patch needs to be as small as possible, not adding "nice to have" >> features (like support for parallel queries - I very much doubt just >> using shared instead of local buffers is enough to make it work.) >>=20 >> regards >>=20 >> --=20 >> Tomas Vondra http://www.2ndQuadrant.com = <http://www.2ndquadrant.com/> >> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services >=20 --Apple-Mail=_56A6B3F9-3268-444C-9A38-9CE6B6557497 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 <html><head><meta http-equiv=3D"Content-Type" content=3D"text/html; = charset=3Dutf-8"></head><body style=3D"word-wrap: break-word; = -webkit-nbsp-mode: space; line-break: after-white-space;" class=3D"">Thank= you for review my patch.<div class=3D""><br class=3D""><div><br = class=3D""><blockquote type=3D"cite" class=3D""><div = class=3D"">2020=E5=B9=B41=E6=9C=8812=E6=97=A5 =E4=B8=8A=E5=8D=884:27=EF=BC= =8CPavel Stehule <<a href=3D"mailto:[email protected]" = class=3D"">[email protected]</a>> =E5=86=99=E9=81=93=EF=BC=9A</di= v><br class=3D"Apple-interchange-newline"><div class=3D""><div dir=3D"ltr"= class=3D""><div class=3D"">Hi<br class=3D""></div><br class=3D""><div = class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">so 11. 1. = 2020 v 15:00 odes=C3=ADlatel =E6=9B=BE=E6=96=87=E6=97=8C(=E4=B9=89=E4= =BB=8E) <<a href=3D"mailto:[email protected]" = class=3D"">[email protected]</a>> napsal:<br = class=3D""></div><blockquote class=3D"gmail_quote" style=3D"margin:0px = 0px 0px 0.8ex;border-left:1px solid = rgb(204,204,204);padding-left:1ex"><div style=3D"overflow-wrap: = break-word;" class=3D"">Hi all<div class=3D""><br class=3D""></div><div = class=3D"">This is the latest patch</div><div class=3D""><br = class=3D""></div><div class=3D"">The updates are as follows:</div><div = class=3D"">1. Support global temp Inherit table <span style=3D"" = class=3D"">global temp partition table</span></div><div class=3D""><span = style=3D"" class=3D"">2. Support </span><font class=3D""><span = class=3D"">serial column in GTT</span></font></div><div class=3D""><span = style=3D"" class=3D"">3. </span><font class=3D""><span = class=3D"">Provide views pg_gtt_relstats pg_gtt_stats for = GTT=E2=80=99s statistics</span></font></div><div class=3D""><span = style=3D"" class=3D"">4. </span><span style=3D"" = class=3D"">Provide</span> view <span style=3D"" = class=3D"">pg_gtt_attached_pids to </span><span style=3D"" = class=3D"">manage GTT</span></div><div class=3D""><span style=3D"" = class=3D"">5. </span><span style=3D"" class=3D"">Provide = function </span><font class=3D"">pg_list_gtt_relfrozenxids() to = manage GTT</font></div><div class=3D""><font class=3D"">6. <span= class=3D"">Alter GTT or rename GTT is allowed under some = conditions</span></font></div><div class=3D""><br class=3D""></div><div = class=3D""><br class=3D""></div><div class=3D"">Please give me = feedback.</div></div></blockquote><div class=3D""><br = class=3D""></div><div class=3D"">I tested the functionality</div><div = class=3D""><br class=3D""></div><div class=3D"">1. i think so "ON COMMIT = PRESERVE ROWS" should be default mode (like local temp = tables).</div></div></div></div></blockquote>makes sense, I will fix = it.</div><div><br class=3D""><blockquote type=3D"cite" class=3D""><div = class=3D""><div dir=3D"ltr" class=3D""><div class=3D"gmail_quote"><div = class=3D""><br class=3D""></div><div class=3D"">I tested some simple = scripts <br class=3D""></div><div class=3D""><br class=3D""></div><div = class=3D"">test01.sql</div><div class=3D""><br class=3D""></div><div = class=3D"">CREATE TEMP TABLE foo(a int, b int);<br class=3D"">INSERT = INTO foo SELECT random()*100, random()*1000 FROM = generate_series(1,1000);<br class=3D"">ANALYZE foo;<br class=3D"">SELECT = sum(a), sum(b) FROM foo;<br class=3D"">DROP TABLE foo; -- simulate = disconnect<br class=3D""></div><div class=3D""><br class=3D""></div><div = class=3D""><br class=3D""></div><div class=3D"">after 100 sec, the table = pg_attribute has 3.2MB</div><div class=3D"">and 64 tps, 6446 = transaction<br class=3D""></div><div class=3D""><br class=3D""></div><div = class=3D"">test02.sql</div><div class=3D""><br class=3D""></div><div = class=3D"">INSERT INTO foo SELECT random()*100, random()*1000 FROM = generate_series(1,1000);<br class=3D"">ANALYZE foo;<br class=3D"">SELECT = sum(a), sum(b) FROM foo;<br class=3D"">DELETE FROM foo; -- simulate = disconnect<br class=3D""></div><div class=3D""><br class=3D""></div><div = class=3D""><br class=3D""></div><div class=3D"">after 100 sec, 1688 tps, = 168830 transactions</div><div class=3D""><br class=3D""></div><div = class=3D"">So performance is absolutely different as we = expected.</div><div class=3D""><br class=3D""></div><div class=3D"">=46rom= my perspective, this functionality is = great.</div></div></div></div></blockquote>Yes, frequent ddl = causes <span style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, = 0);" class=3D"">catalog bloat, </span><font color=3D"#000000" = class=3D""><span style=3D"caret-color: rgb(0, 0, 0);" class=3D"">GTT = avoids this problem.</span></font></div><div><font color=3D"#000000" = class=3D""><span style=3D"caret-color: rgb(0, 0, 0);" class=3D""><br = class=3D""></span></font><blockquote type=3D"cite" class=3D""><div = class=3D""><div dir=3D"ltr" class=3D""><div class=3D"gmail_quote"><div = class=3D""><br class=3D""></div><div class=3D"">Todo:</div><div = class=3D""><br class=3D""></div><div class=3D"">pg_table_size function = doesn't work</div></div></div></div></blockquote>Do you mean that = function <span style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, = 0);" class=3D"">pg_table_size() need get</span> the storage space = used by the one GTT in the entire db(include all session) = .</div><div><br class=3D""><blockquote type=3D"cite" class=3D""><div = class=3D""><div dir=3D"ltr" class=3D""><div class=3D"gmail_quote"><div = class=3D""><br class=3D""></div><div class=3D"">Regards</div><div = class=3D""><br class=3D""></div><div class=3D"">Pavel<br = class=3D""></div><div class=3D""><br class=3D""></div><blockquote = class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px = solid rgb(204,204,204);padding-left:1ex"><div style=3D"overflow-wrap: = break-word;" class=3D""><div class=3D""><br class=3D""></div><div = class=3D"">Wenjing</div><div class=3D""><br class=3D""></div><div = class=3D""><br class=3D""></div><div class=3D""><br class=3D""></div><div = class=3D""></div></div><div style=3D"overflow-wrap: break-word;" = class=3D""><div class=3D""><br class=3D""><div class=3D""><br = class=3D""><blockquote type=3D"cite" class=3D""><div = class=3D"">2020=E5=B9=B41=E6=9C=886=E6=97=A5 =E4=B8=8A=E5=8D=884:06=EF=BC=8C= Tomas Vondra <<a href=3D"mailto:[email protected]" = target=3D"_blank" class=3D"">[email protected]</a>> = =E5=86=99=E9=81=93=EF=BC=9A</div><br class=3D""><div class=3D""><div = class=3D"">Hi,<br class=3D""><br class=3D"">I think we need to do = something with having two patches aiming to add<br class=3D"">global = temporary tables:<br class=3D""><br class=3D"">[1] <a = href=3D"https://commitfest.postgresql.org/26/2349/" target=3D"_blank" = class=3D"">https://commitfest.postgresql.org/26/2349/</a><br = class=3D""><br class=3D"">[2] <a = href=3D"https://commitfest.postgresql.org/26/2233/" target=3D"_blank" = class=3D"">https://commitfest.postgresql.org/26/2233/</a><br = class=3D""><br class=3D"">As a reviewer I have no idea which of the = threads to look at - certainly<br class=3D"">not without reading both = threads, which I doubt anyone will really do.<br class=3D"">The reviews = and discussions are somewhat intermixed between those two<br = class=3D"">threads, which makes it even more confusing.<br class=3D""><br = class=3D"">I think we should agree on a minimal patch combining the = necessary/good<br class=3D"">bits from the various patches, and = terminate one of the threads (i.e.<br class=3D"">mark it as rejected or = RWF). And we need to do that now, otherwise<br class=3D"">there's about = 0% chance of getting this into v13.<br class=3D""><br class=3D"">In = general, I agree with the sentiment Rober expressed in [1] - the<br = class=3D"">patch needs to be as small as possible, not adding "nice to = have"<br class=3D"">features (like support for parallel queries - I very = much doubt just<br class=3D"">using shared instead of local buffers is = enough to make it work.)<br class=3D""><br class=3D"">regards<br = class=3D""><br class=3D"">-- <br class=3D"">Tomas Vondra = &n= bsp; <a href=3D"http://www.2ndquadrant.com/" = target=3D"_blank" class=3D"">http://www.2ndQuadrant.com</a><br = class=3D"">PostgreSQL Development, 24x7 Support, Remote DBA, Training = & Services</div></div></blockquote></div><br = class=3D""></div></div></blockquote></div></div> </div></blockquote></div><br class=3D""></div></body></html>= --Apple-Mail=_56A6B3F9-3268-444C-9A38-9CE6B6557497--