Thread
-
WIP: store additional info in GIN index
Alexander Korotkov <aekorotkov@gmail.com> — 2012-11-18T21:54:53Z
Hackers, Attached patch enables GIN to store additional information with item pointers in posting lists and trees. Such additional information could be positions of words, positions of trigrams, lengths of arrays and so on. This is the first and most huge patch of serie of GIN improvements which was presented at PGConf.EU http://wiki.postgresql.org/images/2/25/Full-text_search_in_PostgreSQL_in_milliseconds-extended-version.pdf Patch modifies GIN interface as following: 1) Two arguments are added to extractValue Datum **addInfo, bool **addInfoIsNull 2) Two arguments are added to consistent Datum addInfo[], bool addInfoIsNull[] 3) New method config is introduced which returns datatype oid of addtional information (analogy with SP-GiST config method). Patch completely changes storage in posting lists and leaf pages of posting trees. It uses varbyte encoding for BlockNumber and OffsetNumber. BlockNumber are stored incremental in page. Additionally one bit of OffsetNumber is reserved for additional information NULL flag. To be able to find position in leaf data page quickly patch introduces small index in the end of page. ------ With best regards, Alexander Korotkov.
-
Re: WIP: store additional info in GIN index
Tomas Vondra <tv@fuzzy.cz> — 2012-12-02T01:02:15Z
On 18.11.2012 22:54, Alexander Korotkov wrote: > Hackers, > > Patch completely changes storage in posting lists and leaf pages of > posting trees. It uses varbyte encoding for BlockNumber and > OffsetNumber. BlockNumber are stored incremental in page. Additionally > one bit of OffsetNumber is reserved for additional information NULL > flag. To be able to find position in leaf data page quickly patch > introduces small index in the end of page. Hi, I've tried to apply the patch with the current HEAD, but I'm getting segfaults whenever VACUUM runs (either called directly or from autovac workers). The patch applied cleanly against 9b3ac49e and needed a minor fix when applied on HEAD (because of an assert added to ginRedoCreatePTree), but that shouldn't be a problem. The backtrace always looks like this: Program received signal SIGSEGV, Segmentation fault. 0x00000000004dea3b in processPendingPage (accum=0x7fff15ab8aa0, ka=0x7fff15ab8a70, page=0x7f88774a7ea0 "", startoff=1) at ginfast.c:785 785 addInfo = index_getattr(itup, 2, accum->ginstate->tupdesc[curattnum - 1], &addInfoIsNull); (gdb) bt #0 0x00000000004dea3b in processPendingPage (accum=0x7fff15ab8aa0, ka=0x7fff15ab8a70, page=0x7f88774a7ea0 "", startoff=1) at ginfast.c:785 #1 0x00000000004df3c6 in ginInsertCleanup (ginstate=0x7fff15ab97c0, vac_delay=1 '\001', stats=0xfb0050) at ginfast.c:909 #2 0x00000000004dbe8c in ginbulkdelete (fcinfo=0x7fff15abbfb0) at ginvacuum.c:747 Reproducing the issue is quite simple: 1) create table messages (id int, txt text, ts tsvector); 2) insert into messages select i, substr(md5(i::text), 0, 4), to_tsvector('english', substr(md5(i::text), 0, 4)) from generate_series(1,100000) s(i); 3) vacuum messages 4) ... segfault :-( regards Tomas -
Re: WIP: store additional info in GIN index
Robert Haas <robertmhaas@gmail.com> — 2012-12-04T17:34:51Z
On Sun, Nov 18, 2012 at 4:54 PM, Alexander Korotkov <aekorotkov@gmail.com> wrote: > Patch completely changes storage in posting lists and leaf pages of posting > trees. It uses varbyte encoding for BlockNumber and OffsetNumber. > BlockNumber are stored incremental in page. Additionally one bit of > OffsetNumber is reserved for additional information NULL flag. To be able to > find position in leaf data page quickly patch introduces small index in the > end of page. This sounds like it means that this would break pg_upgrade, about which I'm not too keen. Ideally, we'd like to have a situation where new indexes have additional capabilities, but old indexes are still usable for things that they could do before. I am not sure whether that's a realistic goal. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
-
Re: WIP: store additional info in GIN index
Josh Berkus <josh@agliodbs.com> — 2012-12-04T18:04:03Z
On 12/4/12 9:34 AM, Robert Haas wrote: > On Sun, Nov 18, 2012 at 4:54 PM, Alexander Korotkov > <aekorotkov@gmail.com> wrote: >> Patch completely changes storage in posting lists and leaf pages of posting >> trees. It uses varbyte encoding for BlockNumber and OffsetNumber. >> BlockNumber are stored incremental in page. Additionally one bit of >> OffsetNumber is reserved for additional information NULL flag. To be able to >> find position in leaf data page quickly patch introduces small index in the >> end of page. > > This sounds like it means that this would break pg_upgrade, about > which I'm not too keen. Ideally, we'd like to have a situation where > new indexes have additional capabilities, but old indexes are still > usable for things that they could do before. I am not sure whether > that's a realistic goal. Is there a reason not to create this as a new type of index? "GIN2" or whatever? -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com
-
Re: WIP: store additional info in GIN index
Andres Freund <andres@2ndquadrant.com> — 2012-12-04T18:05:44Z
On 2012-12-04 10:04:03 -0800, Josh Berkus wrote: > On 12/4/12 9:34 AM, Robert Haas wrote: > > On Sun, Nov 18, 2012 at 4:54 PM, Alexander Korotkov > > <aekorotkov@gmail.com> wrote: > >> Patch completely changes storage in posting lists and leaf pages of posting > >> trees. It uses varbyte encoding for BlockNumber and OffsetNumber. > >> BlockNumber are stored incremental in page. Additionally one bit of > >> OffsetNumber is reserved for additional information NULL flag. To be able to > >> find position in leaf data page quickly patch introduces small index in the > >> end of page. > > > > This sounds like it means that this would break pg_upgrade, about > > which I'm not too keen. Ideally, we'd like to have a situation where > > new indexes have additional capabilities, but old indexes are still > > usable for things that they could do before. I am not sure whether > > that's a realistic goal. > > Is there a reason not to create this as a new type of index? "GIN2" or > whatever? Aren't the obvious maintenance problems enough? Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
-
Re: WIP: store additional info in GIN index
Alexander Korotkov <aekorotkov@gmail.com> — 2012-12-04T19:12:11Z
Hi! On Sun, Dec 2, 2012 at 5:02 AM, Tomas Vondra <tv@fuzzy.cz> wrote: > I've tried to apply the patch with the current HEAD, but I'm getting > segfaults whenever VACUUM runs (either called directly or from autovac > workers). > > The patch applied cleanly against 9b3ac49e and needed a minor fix when > applied on HEAD (because of an assert added to ginRedoCreatePTree), but > that shouldn't be a problem. > Thanks for testing! Patch is rebased with HEAD. The bug you reported was fixed. ------ With best regards, Alexander Korotkov.
-
Re: WIP: store additional info in GIN index
Alexander Korotkov <aekorotkov@gmail.com> — 2012-12-04T19:30:21Z
On Tue, Dec 4, 2012 at 9:34 PM, Robert Haas <robertmhaas@gmail.com> wrote: > On Sun, Nov 18, 2012 at 4:54 PM, Alexander Korotkov > <aekorotkov@gmail.com> wrote: > > Patch completely changes storage in posting lists and leaf pages of > posting > > trees. It uses varbyte encoding for BlockNumber and OffsetNumber. > > BlockNumber are stored incremental in page. Additionally one bit of > > OffsetNumber is reserved for additional information NULL flag. To be > able to > > find position in leaf data page quickly patch introduces small index in > the > > end of page. > > This sounds like it means that this would break pg_upgrade, about > which I'm not too keen. Ideally, we'd like to have a situation where > new indexes have additional capabilities, but old indexes are still > usable for things that they could do before. I am not sure whether > that's a realistic goal. This means to have two versions of code which deals with posting trees and lists. For me it seems unlikely we have resources for maintenance of this. ------ With best regards, Alexander Korotkov.
-
Re: WIP: store additional info in GIN index
Alvaro Herrera <alvherre@2ndquadrant.com> — 2012-12-04T20:35:24Z
Alexander Korotkov escribió: > On Tue, Dec 4, 2012 at 9:34 PM, Robert Haas <robertmhaas@gmail.com> wrote: > > > On Sun, Nov 18, 2012 at 4:54 PM, Alexander Korotkov > > <aekorotkov@gmail.com> wrote: > > > Patch completely changes storage in posting lists and leaf pages of > > posting > > > trees. It uses varbyte encoding for BlockNumber and OffsetNumber. > > > BlockNumber are stored incremental in page. Additionally one bit of > > > OffsetNumber is reserved for additional information NULL flag. To be > > able to > > > find position in leaf data page quickly patch introduces small index in > > the > > > end of page. > > > > This sounds like it means that this would break pg_upgrade, about > > which I'm not too keen. Ideally, we'd like to have a situation where > > new indexes have additional capabilities, but old indexes are still > > usable for things that they could do before. I am not sure whether > > that's a realistic goal. > > This means to have two versions of code which deals with posting trees and > lists. For me it seems unlikely we have resources for maintenance of this. Witness how GIN has gone with unfixed bugs for months, even though patches to fix them have been posted. We don't have the manpower to maintain even *one* such implementation, let alone two. Maybe we can mark GIN indexes as invalid after pg_upgrade somehow, so that they require reindex in the new cluster before they can be used for queries or index updates. -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
-
Re: WIP: store additional info in GIN index
Bruce Momjian <bruce@momjian.us> — 2012-12-04T20:38:06Z
On Tue, Dec 4, 2012 at 05:35:24PM -0300, Alvaro Herrera wrote: > > This means to have two versions of code which deals with posting trees and > > lists. For me it seems unlikely we have resources for maintenance of this. > > Witness how GIN has gone with unfixed bugs for months, even though > patches to fix them have been posted. We don't have the manpower to > maintain even *one* such implementation, let alone two. > > Maybe we can mark GIN indexes as invalid after pg_upgrade somehow, so > that they require reindex in the new cluster before they can be used for > queries or index updates. Yes, pg_upgrade has infrastructure to do that. -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. +
-
Re: WIP: store additional info in GIN index
Tomas Vondra <tv@fuzzy.cz> — 2012-12-04T21:56:19Z
On 4.12.2012 20:12, Alexander Korotkov wrote: > Hi! > > On Sun, Dec 2, 2012 at 5:02 AM, Tomas Vondra <tv@fuzzy.cz > <mailto:tv@fuzzy.cz>> wrote: > > I've tried to apply the patch with the current HEAD, but I'm getting > segfaults whenever VACUUM runs (either called directly or from autovac > workers). > > The patch applied cleanly against 9b3ac49e and needed a minor fix when > applied on HEAD (because of an assert added to ginRedoCreatePTree), but > that shouldn't be a problem. > > > Thanks for testing! Patch is rebased with HEAD. The bug you reported was > fixed. Applies fine, but I get a segfault in dataPlaceToPage at gindatapage.c. The whole backtrace is here: http://pastebin.com/YEPuWeuV The messages written into PostgreSQL log are quite variable - usually it looks like this: 2012-12-04 22:31:08 CET 31839 LOG: database system was not properly shut down; automatic recovery in progress 2012-12-04 22:31:08 CET 31839 LOG: redo starts at 0/68A76E48 2012-12-04 22:31:08 CET 31839 LOG: unexpected pageaddr 0/1BE64000 in log segment 000000010000000000000069, offset 15089664 2012-12-04 22:31:08 CET 31839 LOG: redo done at 0/69E63638 but I've seen this message too 2012-12-04 22:20:29 CET 31709 LOG: database system was not properly shut down; automatic recovery in progress 2012-12-04 22:20:29 CET 31709 LOG: redo starts at 0/AEAFAF8 2012-12-04 22:20:29 CET 31709 LOG: record with zero length at 0/C7D5698 2012-12-04 22:20:29 CET 31709 LOG: redo done at 0/C7D55E I wasn't able to prepare a simple testcase to reproduce this, so I've attached two files from my "fun project" where I noticed it. It's a simple DB + a bit of Python for indexing mbox archives inside Pg. - create.sql - a database structure with a bunch of GIN indexes on tsvector columns on "messages" table - load.py - script for parsing mbox archives / loading them into the "messages" table (warning: it's a bit messy) Usage: 1) create the DB structure $ createdb archives $ psql archives < create.sql 2) fetch some archives (I consistently get SIGSEGV after first three) $ wget http://archives.postgresql.org/pgsql-hackers/mbox/pgsql-hackers.1997-01.gz $ wget http://archives.postgresql.org/pgsql-hackers/mbox/pgsql-hackers.1997-02.gz $ wget http://archives.postgresql.org/pgsql-hackers/mbox/pgsql-hackers.1997-03.gz 3) gunzip and load them using the python script $ gunzip pgsql-hackers.*.gz $ ./load.py --db archives pgsql-hackers.* 4) et voila - a SIGSEGV :-( I suspect this might be related to the fact that the load.py script uses savepoints quite heavily to handle UNIQUE_VIOLATION (duplicate messages). Tomas -
Re: WIP: store additional info in GIN index
Tom Lane <tgl@sss.pgh.pa.us> — 2012-12-04T22:35:27Z
Alvaro Herrera <alvherre@2ndquadrant.com> writes: > Maybe we can mark GIN indexes as invalid after pg_upgrade somehow, so > that they require reindex in the new cluster before they can be used for > queries or index updates. Bumping the version number in the GIN metapage would be sufficient. regards, tom lane
-
Re: WIP: store additional info in GIN index
Bruce Momjian <bruce@momjian.us> — 2012-12-04T22:47:07Z
On Tue, Dec 4, 2012 at 05:35:27PM -0500, Tom Lane wrote: > Alvaro Herrera <alvherre@2ndquadrant.com> writes: > > Maybe we can mark GIN indexes as invalid after pg_upgrade somehow, so > > that they require reindex in the new cluster before they can be used for > > queries or index updates. > > Bumping the version number in the GIN metapage would be sufficient. And it is easy for pg_upgrade to report which indexes need rebuilding, and it can create a script file to do the reindexing. -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. +
-
Re: WIP: store additional info in GIN index
Alexander Korotkov <aekorotkov@gmail.com> — 2012-12-05T08:10:58Z
On Wed, Dec 5, 2012 at 1:56 AM, Tomas Vondra <tv@fuzzy.cz> wrote: > On 4.12.2012 20:12, Alexander Korotkov wrote: > > Hi! > > > > On Sun, Dec 2, 2012 at 5:02 AM, Tomas Vondra <tv@fuzzy.cz > > <mailto:tv@fuzzy.cz>> wrote: > > > > I've tried to apply the patch with the current HEAD, but I'm getting > > segfaults whenever VACUUM runs (either called directly or from > autovac > > workers). > > > > The patch applied cleanly against 9b3ac49e and needed a minor fix > when > > applied on HEAD (because of an assert added to ginRedoCreatePTree), > but > > that shouldn't be a problem. > > > > > > Thanks for testing! Patch is rebased with HEAD. The bug you reported was > > fixed. > > Applies fine, but I get a segfault in dataPlaceToPage at gindatapage.c. > The whole backtrace is here: http://pastebin.com/YEPuWeuV > > The messages written into PostgreSQL log are quite variable - usually it > looks like this: > > 2012-12-04 22:31:08 CET 31839 LOG: database system was not properly > shut down; automatic recovery in progress > 2012-12-04 22:31:08 CET 31839 LOG: redo starts at 0/68A76E48 > 2012-12-04 22:31:08 CET 31839 LOG: unexpected pageaddr 0/1BE64000 in > log segment 000000010000000000000069, offset 15089664 > 2012-12-04 22:31:08 CET 31839 LOG: redo done at 0/69E63638 > > but I've seen this message too > > 2012-12-04 22:20:29 CET 31709 LOG: database system was not properly > shut down; automatic recovery in progress > 2012-12-04 22:20:29 CET 31709 LOG: redo starts at 0/AEAFAF8 > 2012-12-04 22:20:29 CET 31709 LOG: record with zero length at 0/C7D5698 > 2012-12-04 22:20:29 CET 31709 LOG: redo done at 0/C7D55E > > > I wasn't able to prepare a simple testcase to reproduce this, so I've > attached two files from my "fun project" where I noticed it. It's a > simple DB + a bit of Python for indexing mbox archives inside Pg. > > - create.sql - a database structure with a bunch of GIN indexes on > tsvector columns on "messages" table > > - load.py - script for parsing mbox archives / loading them into the > "messages" table (warning: it's a bit messy) > > > Usage: > > 1) create the DB structure > $ createdb archives > $ psql archives < create.sql > > 2) fetch some archives (I consistently get SIGSEGV after first three) > $ wget > http://archives.postgresql.org/pgsql-hackers/mbox/pgsql-hackers.1997-01.gz > $ wget > http://archives.postgresql.org/pgsql-hackers/mbox/pgsql-hackers.1997-02.gz > $ wget > http://archives.postgresql.org/pgsql-hackers/mbox/pgsql-hackers.1997-03.gz > > 3) gunzip and load them using the python script > $ gunzip pgsql-hackers.*.gz > $ ./load.py --db archives pgsql-hackers.* > > 4) et voila - a SIGSEGV :-( > > > I suspect this might be related to the fact that the load.py script uses > savepoints quite heavily to handle UNIQUE_VIOLATION (duplicate messages). > Thanks for bug report. It is fixed in the attached patch. ------ With best regards, Alexander Korotkov.
-
Re: WIP: store additional info in GIN index
Tomas Vondra <tv@fuzzy.cz> — 2012-12-06T01:44:58Z
On 5.12.2012 09:10, Alexander Korotkov wrote: > On Wed, Dec 5, 2012 at 1:56 AM, Tomas Vondra <tv@fuzzy.cz > <mailto:tv@fuzzy.cz>> wrote: > > Thanks for bug report. It is fixed in the attached patch. Hi, I gave it another try and this time it went fine - I didn't get any segfault when loading the data, which is a good news. Then I've run a simple benchmarking script, and the results are not as good as I expected, actually I'm getting much worse performance than with the original GIN index. The following table contains the time of loading the data (not a big difference), and number of queries per minute for various number of words in the query. The queries looks like this SELECT id FROM messages WHERE body_tsvector @@ plainto_tsquery('english', 'word1 word2 ...') so it's really the simplest form of FTS query possible. without patch | with patch -------------------------------------------- loading 750 sec | 770 sec 1 word 1500 | 1100 2 words 23000 | 9800 3 words 24000 | 9700 4 words 16000 | 7200 -------------------------------------------- I'm not saying this is a perfect benchmark, but the differences (of querying) are pretty huge. Not sure where this difference comes from, but it seems to be quite consistent (I usually get +-10% results, which is negligible considering the huge difference). Is this an expected behaviour that will be fixed by another patch? The database contains ~680k messages from the mailing list archives, i.e. about 900 MB of data (in the table), and the GIN index on tsvector is about 900MB too. So the whole dataset nicely fits into memory (8GB RAM), and it seems to be completely CPU bound (no I/O activity at all). The configuration was exactly the same in both cases shared buffers = 1GB work mem = 64 MB maintenance work mem = 256 MB I can either upload the database somewhere, or provide the benchmarking script if needed. Tomas -
Re: WIP: store additional info in GIN index
Alexander Korotkov <aekorotkov@gmail.com> — 2012-12-22T16:15:49Z
Hi! On Thu, Dec 6, 2012 at 5:44 AM, Tomas Vondra <tv@fuzzy.cz> wrote: > Then I've run a simple benchmarking script, and the results are not as > good as I expected, actually I'm getting much worse performance than > with the original GIN index. > > The following table contains the time of loading the data (not a big > difference), and number of queries per minute for various number of > words in the query. > > The queries looks like this > > SELECT id FROM messages > WHERE body_tsvector @@ plainto_tsquery('english', 'word1 word2 ...') > > so it's really the simplest form of FTS query possible. > > without patch | with patch > -------------------------------------------- > loading 750 sec | 770 sec > 1 word 1500 | 1100 > 2 words 23000 | 9800 > 3 words 24000 | 9700 > 4 words 16000 | 7200 > -------------------------------------------- > > I'm not saying this is a perfect benchmark, but the differences (of > querying) are pretty huge. Not sure where this difference comes from, > but it seems to be quite consistent (I usually get +-10% results, which > is negligible considering the huge difference). > > Is this an expected behaviour that will be fixed by another patch? > Another patches which significantly accelerate index search will be provided. This patch changes only GIN posting lists/trees storage. However, it wasn't expected that this patch significantly changes index scan speed in any direction. The database contains ~680k messages from the mailing list archives, > i.e. about 900 MB of data (in the table), and the GIN index on tsvector > is about 900MB too. So the whole dataset nicely fits into memory (8GB > RAM), and it seems to be completely CPU bound (no I/O activity at all). > > The configuration was exactly the same in both cases > > shared buffers = 1GB > work mem = 64 MB > maintenance work mem = 256 MB > > I can either upload the database somewhere, or provide the benchmarking > script if needed. Unfortunately, I can't reproduce such huge slowdown on my testcases. Could you share both database and benchmarking script? ------ With best regards, Alexander Korotkov. -
Re: WIP: store additional info in GIN index
Tomas Vondra <tv@fuzzy.cz> — 2012-12-23T23:48:49Z
Hi! On 22.12.2012 17:15, Alexander Korotkov wrote: > I'm not saying this is a perfect benchmark, but the differences (of > querying) are pretty huge. Not sure where this difference comes from, > but it seems to be quite consistent (I usually get +-10% results, which > is negligible considering the huge difference). > > Is this an expected behaviour that will be fixed by another patch? > > > Another patches which significantly accelerate index search will be > provided. This patch changes only GIN posting lists/trees storage. > However, it wasn't expected that this patch significantly changes index > scan speed in any direction. That was exactly my expectation - probably not an improvement, but definitely not a worse performance. > > The database contains ~680k messages from the mailing list archives, > i.e. about 900 MB of data (in the table), and the GIN index on tsvector > is about 900MB too. So the whole dataset nicely fits into memory (8GB > RAM), and it seems to be completely CPU bound (no I/O activity at all). > > The configuration was exactly the same in both cases > > shared buffers = 1GB > work mem = 64 MB > maintenance work mem = 256 MB > > I can either upload the database somewhere, or provide the benchmarking > script if needed. > > > Unfortunately, I can't reproduce such huge slowdown on my testcases. > Could you share both database and benchmarking script? It's strange, but no matter what I do I can't reproduce those results (with the significant performance decrease). So either I've done some strange mistake when running those tests, or there was something wrong with my system, or whatever :-( But when running the benchmarks now (double-checked everything, properly repeated the tests, ...), I've noticed a different behaviour. But first some info about the scripts I use for testing. All the scripts are available here: https://bitbucket.org/tvondra/archie It's my "hobby project" implementing fulltext mbox archive. It should be usable but it's still a bit WIP so let me know in case of any issues. The README should give you all the instructions on how to setup and load the database. I'm using ~1700 mbox files downloaded from http://archives.postgresql.org/ for these lists (until 2012/11): pgadmin-hackers pgsql-advocacy pgsql-announce pgsql-bugs pgsql-general pgsql-hackers pgsql-jdbc pgsql-novice pgsql-odbc pgsql-patches pgsql-sql which in the end gives ~677k rows in the 'messages' table, occupying ~5.5GB disk space (including all the indexes etc). Once you have the data loaded, you need to warmup the database and then start benchmarking it - I'm using the warmup.py script to both things. The script is quite simple, it basically just To warmup the DB, just run this ./warmup.py --db archie --duration 300 until the %util drops near 0 (assuming you have enough RAM to fit the whole database into memory). Then I usually do this as a benchmarking ./warmup.py --db archie --duration 300 --no-hash \ --no-thread --words 1 ./warmup.py --db archie --duration 300 --no-hash \ --no-thread --words 2 which runs 60-second tests and outputs one line for worker (by default equal to the number of CPUs). The script itself is very simple, it fetches a random message and uses the tsvector column as a source of words for the actual benchmark. It takes N words from the tsvector, splits them into groups and performs a simple fulltext query using plainto_tsquery('word1 word2 ...'). At the end it prints info including the number of queries per second. I've run the tests on the current master with and without the v3 patch. I've tested it with 1GB or 2GB shared buffers, and 32MB or 64MB work mem. The tests were run for 1, 2, 3, 4 and 5 words, and I've repeated it five times for each configuration. Duration of each run was 5-minutes. These are the averages (from the 5 runs) of queries per second for each combination of parameters: 1 2 3 4 5 ---------------------------------------------------- master 1GB/32MB 19 179 165 127 99 patched 1GB/32MB 19 175 163 124 96 master 1GB/64MB 20 181 165 127 99 patched 1GB/64MB 19 174 159 120 95 master 2GB/32MB 27 181 165 127 98 patched 2GB/32MB 25 176 156 120 93 master 2GB/64MB 27 180 166 128 102 patched 2GB/64MB 40 402 364 245 176 There's no significant difference in performance, except for the 2GB/64MB combination. And in that case it's actually the opposite direction than I've reported before - i.e. this time it's up to 100% faster than the unpatched master. The results are pretty consistent (very small variance across the repeated runs), so I'm not sure about the previous results. Any idea what might cause such behavior? Why should it happen only with this particular combination of shared_buffers and work_mem? kind regards Tomas -
Re: WIP: store additional info in GIN index
Craig Ringer <craig@2ndquadrant.com> — 2013-03-03T14:53:15Z
The GIN changes don't seem to have progressed in some time, and some of the most recent activity (http://archives.postgresql.org/message-id/50BFF89A.7080908@fuzzy.cz) suggests unconvincing test results. Is this work considered to be a dead-end - a good idea that didn't work out in practice? Or do you think it still has merit and can be made useful and ready for inclusion? Given the activity level I would like to bounce this patch, either as "returned with feedback" if you want to take another go at it post-9.3, or as "rejected" if you think the idea won't go anywhere. Please let me know how you think it looks. -- Craig Ringer http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
-
Re: WIP: store additional info in GIN index
Alexander Korotkov <aekorotkov@gmail.com> — 2013-03-03T17:29:57Z
On Sun, Mar 3, 2013 at 6:53 PM, Craig Ringer <craig@2ndquadrant.com> wrote: > The GIN changes don't seem to have progressed in some time, and some of > the most recent activity > (http://archives.postgresql.org/message-id/50BFF89A.7080908@fuzzy.cz) > suggests unconvincing test results. > Actually, _most_ recent acitivity showing inverse http://www.postgresql.org/message-id/50D79861.3030303@fuzzy.cz However, this patch itself is not expected to give significant changes in search speed. Testing results with both double acceleration and slowdown looks strange for me. I can't either reproduce it or explain. Is this work considered to be a dead-end - a good idea that didn't work > out in practice? Or do you think it still has merit and can be made > useful and ready for inclusion? > This patch is only first of future serie of GIN improvements patches. It doesn't change anything significant in search, only in storage. This time we are working on design of rest of patches in order to put them on the consideration. This lead to lack of attention to this patch. Given the activity level I would like to bounce this patch, either as > "returned with feedback" if you want to take another go at it post-9.3, > or as "rejected" if you think the idea won't go anywhere. Please let me > know how you think it looks. > "Returned with feedback", definitely. ------ With best regards, Alexander Korotkov.
-
Re: WIP: store additional info in GIN index
Craig Ringer <craig@2ndquadrant.com> — 2013-03-04T02:54:19Z
On 03/04/2013 01:29 AM, Alexander Korotkov wrote: Given the activity level I would like to bounce this patch, either as "returned with feedback" if you want to take another go at it post-9.3, or as "rejected" if you think the idea won't go anywhere. Please let me know how you think it looks. "Returned with feedback", definitely. Done, and thankyou for taking the time to explain and write such a clear response that'll be useful if others have reason to look into the same area later. -- Craig Ringer http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services