[GENERAL] Performance problem with query
Good morning list, the following query takes about 15 to 20 minutes for around 2 million lines in the file myfile.txt, but with 8 million lines it takes around 5 hours and i just don't understand why there is such a huge discrepancy in performance. COPY public.temp_table FROM 'myfile.txt' WITH DELIMITER '\t'; INSERT INTO public.master(pid,smid, val1, val2, chr) SELECT pid, smid, val1, val12, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; INSERT INTO public.values(smid, pos, chr) SELECT DISTINCT smid, pos, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; I came up with this query, because i wanted to use the COPY command to load huge files into the db, but i don't want to load all the columns contained in the file in only one table but copy some of them into one table and some in a second table. As i found out with logging, the data is loaded into temp_table within 15 minutes, but to transfer it from the temp_table to public.master took around 5 hours and from temp_table to public.values took again only something like 10 minutes. Can it be that the cast takes up so much more time than when reading and transferring 2 million lines? Thanks for any advice! -- Christian Rengstl M.A. Klinik und Poliklinik für Innere Medizin II Kardiologie - Forschung Universitätsklinikum Regensburg B3 1.388 Franz-Josef-Strauss-Allee 11 93053 Regensburg Tel.: +49-941-944-7230 ---(end of broadcast)--- TIP 5: don't forget to increase your free space map settings
Re: [GENERAL] Performance problem with query
On 7/13/06, Christian Rengstl <[EMAIL PROTECTED]> wrote: Good morning list, the following query takes about 15 to 20 minutes for around 2 million lines in the file myfile.txt, but with 8 million lines it takes around 5 hours and i just don't understand why there is such a huge discrepancy in performance. on the surface it doesn't make sense, can you post an explain analyze? merlin ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster
Re: [GENERAL] Performance problem with query
On 7/14/06, Christian Rengstl <[EMAIL PROTECTED]> wrote: Hi, somehow my reply yesterday got lost, but nevertheless here comes the explain analyze again. It's the explain of the operation that causes this huge performance discrepancy. Unfortunately i had to perform the explain analyze with an empty temp_table, because after the whole operation is done, i delete the data again to save some space. that's not much help. remember that explain analyze actually performs your query. so next time you run it, do explain analyze and post results here. just quick tip: run analyze before you run your big query. merlin ---(end of broadcast)--- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
Antw: [GENERAL] Performance problem with query
now finally after a long time i have the query plan for the whole filled table. I hope somebody can explain me why it takes so much longer... QUERY PLAN - Result (cost=0.09..254643.09 rows=8044000 width=39) (actual time=0.043..0.043 rows=0 loops=1) One-Time Filter: split_part(($1)::text, '_'::text, 2))::smallint = 1) IS NOT TRUE) AND (((split_part(($2)::text, '_'::text, 2))::smallint = 22) IS NOT TR UE)) InitPlan -> Limit (cost=0.00..0.02 rows=1 width=10) (never executed) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (never executed) -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.006..0.006 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.004..0.004 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=10) (never executed) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (never executed) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) (nev er executed) Total runtime: 0.238 ms Result (cost=0.06..254643.06 rows=8044000 width=39) (actual time=0.056..655772 .273 rows=8044000 loops=1) One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 1) InitPlan -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.003..0.003 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.002..0.002 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.006..0.007 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.004..0.004 rows=1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) (act ual time=0.002..191672.344 rows=8044000 loops=1) Total runtime: 62259544.896 ms Result (cost=0.06..254643.06 rows=8044000 width=39) (actual time=1.245..1.245 rows=0 loops=1) One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 22) InitPlan -> Limit (cost=0.00..0.02 rows=1 width=10) (never executed) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (never executed) -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.013..0.014 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.009..0.009 rows=1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) (nev er executed) Total runtime: 22.270 ms (31 Zeilen) >>> "Christian Rengstl" <[EMAIL PROTECTED]> 13.07.06 8.37 Uhr >>> Good morning list, the following query takes about 15 to 20 minutes for around 2 million lines in the file myfile.txt, but with 8 million lines it takes around 5 hours and i just don't understand why there is such a huge discrepancy in performance. COPY public.temp_table FROM 'myfile.txt' WITH DELIMITER '\t'; INSERT INTO public.master(pid,smid, val1, val2, chr) SELECT pid, smid, val1, val12, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; INSERT INTO public.values(smid, pos, chr) SELECT DISTINCT smid, pos, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; I came up with this query, because i wanted to use the COPY command to load huge files into the db, but i don't want to load all the columns contained in the file in only one table but copy some of them into one table and some in a second table. As i found out with logging, the data is loaded into temp_table within 15 minutes, but to transfer it from the temp_table toagain only something like 10 minutes. Can it be that the cast takes up so much more time than when reading and transferring 2 million lines? Thanks for any advice! -- Christian Rengstl M.A. Klinik und Poliklinik für Innere Medizin II Kardiologie - Forschung Universitätsklinikum Regensburg B3 1.388 Franz-Josef-Strauss-Allee 11 93053 Regensburg Tel.: +49-941-944-7230 ---(end of broadcast)--- TIP 5: don't forget to increase your free space map settings ---(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: [GENERAL] Performance problem with query
On 7/18/06, Christian Rengstl <[EMAIL PROTECTED]> wrote: now finally after a long time i have the query plan for the whole filled table. I hope somebody can explain me why it takes so much longer... QUERY PLAN - Result (cost=0.09..254643.09 rows=8044000 width=39) (actual time=0.043..0.043 rows=0 loops=1) One-Time Filter: split_part(($1)::text, '_'::text, 2))::smallint = 1) IS NOT TRUE) AND (((split_part(($2)::text, '_'::text, 2))::smallint = 22) IS NOT TR UE)) InitPlan -> Limit (cost=0.00..0.02 rows=1 width=10) (never executed) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (never executed) -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.006..0.006 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.004..0.004 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=10) (never executed) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (never executed) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) (nev er executed) Total runtime: 0.238 ms Result (cost=0.06..254643.06 rows=8044000 width=39) (actual time=0.056..655772 .273 rows=8044000 loops=1) One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 1) InitPlan -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.003..0.003 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.002..0.002 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.006..0.007 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.004..0.004 rows=1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) (act ual time=0.002..191672.344 rows=8044000 loops=1) Total runtime: 62259544.896 ms Result (cost=0.06..254643.06 rows=8044000 width=39) (actual time=1.245..1.245 rows=0 loops=1) One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 22) InitPlan -> Limit (cost=0.00..0.02 rows=1 width=10) (never executed) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (never executed) -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.013..0.014 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.009..0.009 rows=1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) (nev er executed) Total runtime: 22.270 ms (31 Zeilen) >>> "Christian Rengstl" <[EMAIL PROTECTED]> 13.07.06 8.37 Uhr >>> Good morning list, the following query takes about 15 to 20 minutes for around 2 million lines in the file myfile.txt, but with 8 million lines it takes around 5 hours and i just don't understand why there is such a huge discrepancy in performance. COPY public.temp_table FROM 'myfile.txt' WITH DELIMITER '\t'; INSERT INTO public.master(pid,smid, val1, val2, chr) SELECT pid, smid, val1, val12, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; INSERT INTO public.values(smid, pos, chr) SELECT DISTINCT smid, pos, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; what is this phrase doing exactly? CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) it looks fishy. merlin ---(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: [GENERAL] Performance problem with query
The thing is that in the text file there is a column that is something like xyz_12 and in the table i just need the integer part of it that's what the query is used for. The problem though is not really in the select part, because running the select part on 8 million lines takes about 3 minutes, but i don't know why the insert is taking so long. "Merlin Moncure" <[EMAIL PROTECTED]> wrote on 07/18/06 9:39 pm: > On 7/18/06, Christian Rengstl > <[EMAIL PROTECTED]> wrote: >> now finally after a long time i have the query plan for the whole filled >> table. I hope somebody can explain me why it takes so much longer... >> >> QUERY PLAN >> >> >> >> - >> Result (cost=0.09..254643.09 rows=8044000 width=39) (actual >> time=0.043..0.043 >> rows=0 loops=1) >> One-Time Filter: split_part(($1)::text, '_'::text, 2))::smallint = 1) >> IS >> NOT TRUE) AND (((split_part(($2)::text, '_'::text, 2))::smallint = 22) IS >> NOT TR >> UE)) >> InitPlan >> -> Limit (cost=0.00..0.02 rows=1 width=10) (never executed) >> -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 >> width= >> 10) (never executed) >> -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.006..0.006 >> rows >> =1 loops=1) >> -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 >> width= >> 10) (actual time=0.004..0.004 rows=1 loops=1) >> -> Limit (cost=0.00..0.02 rows=1 width=10) (never executed) >> -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 >> width= >> 10) (never executed) >> -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) >> (nev >> er executed) >> Total runtime: 0.238 ms >> >> Result (cost=0.06..254643.06 rows=8044000 width=39) (actual >> time=0.056..655772 >> .273 rows=8044000 loops=1) >> One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 1) >> InitPlan >> -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.003..0.003 >> rows >> =1 loops=1) >> -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 >> width= >> 10) (actual time=0.002..0.002 rows=1 loops=1) >> -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.006..0.007 >> rows >> =1 loops=1) >> -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 >> width= >> 10) (actual time=0.004..0.004 rows=1 loops=1) >> -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) >> (act >> ual time=0.002..191672.344 rows=8044000 loops=1) >> Total runtime: 62259544.896 ms >> >> Result (cost=0.06..254643.06 rows=8044000 width=39) (actual >> time=1.245..1.245 >> rows=0 loops=1) >> One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 22) >> InitPlan >> -> Limit (cost=0.00..0.02 rows=1 width=10) (never executed) >> -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 >> width= >> 10) (never executed) >> -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.013..0.014 >> rows >> =1 loops=1) >> -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 >> width= >> 10) (actual time=0.009..0.009 rows=1 loops=1) >> -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) >> (nev >> er executed) >> Total runtime: 22.270 ms >> (31 Zeilen) >> >> >> >> >>> "Christian Rengstl" <[EMAIL PROTECTED]> 13.07.06 8.37 Uhr >>> >> Good morning list, >> >> the following query takes about 15 to 20 minutes for around 2 million lines >> in the file myfile.txt, but with 8 million lines it takes around 5 hours and >> i just don't understand why there is such a huge discrepancy in performance. >> >> COPY public.temp_table FROM 'myfile.txt' WITH DELIMITER '\t'; >> >> INSERT INTO public.master(pid,smid, val1, val2, chr) >> SELECT pid, smid, val1, val12, CAST(split_part((SELECT chr from >> public.temp_table LIMIT 1), '_', 2) as int2) >>FROM public.temp_table; >> >> INSERT INTO public.values(smid, pos, chr) >> SELECT DISTINCT smid, pos, CAST(split_part((SELECT chr from >> public.temp_table LIMIT 1), '_', 2) as int2) >> FROM public.temp_table; >> > > what is this phrase doing exactly? > CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) > > it looks fishy. > merlin > > ---(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 -- Christian Rengstl M.A. Klinik und Poliklinik für Innere Medizin II Kardiologie - Forschung Universitätsklinikum Regensburg B3 1.388 Franz-Josef-Strauss-Allee 11 93053 Regensburg Tel.: +49-941-944-7230 --
Re: [GENERAL] Performance problem with query
The analyze is from the exact query and i dropped the indexes before the insert as well without imrpvement. The target table is as well completely empty and the insert is supposed to write, in this case, more or less 8 million lines in the table. There is a rule though, because i have inheritance table structure with one master table and around 20 child tables. Q <[EMAIL PROTECTED]> wrote on 07/19/06 4:37 am: > > On 19/07/2006, at 4:24 AM, Christian Rengstl wrote: > >> now finally after a long time i have the query plan for the whole >> filled table. I hope somebody can explain me why it takes so much >> longer... > > > These explain analyze results don't appear to be from the queries you > posted previously. For these results to mean anything you need to > include the EXACT queries you used to generate them. > >> Result (cost=0.06..254643.06 rows=8044000 width=39) (actual >> time=0.056..655772 >> .273 rows=8044000 loops=1) >> One-Time Filter: ((split_part(($1)::text, '_'::text, >> 2))::smallint = 1) >> InitPlan >> -> Limit (cost=0.00..0.02 rows=1 width=10) (actual >> time=0.003..0.003 rows >> =1 loops=1) >> -> Seq Scan on temp_table (cost=0.00..194313.00 >> rows=8044000 width= >> 10) (actual time=0.002..0.002 rows=1 loops=1) >> -> Limit (cost=0.00..0.02 rows=1 width=10) (actual >> time=0.006..0.007 rows >> =1 loops=1) >> -> Seq Scan on temp_table (cost=0.00..194313.00 >> rows=8044000 width= >> 10) (actual time=0.004..0.004 rows=1 loops=1) >> -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 >> width=39) (act >> ual time=0.002..191672.344 rows=8044000 loops=1) >> Total runtime: 62259544.896 ms > > > This is the query you want to be interested in, the others took no > time at all. > > As a guess I would say the query is an INSERT INTO ... FROM > SELECT ... WHERE (split_part(???, '_', 2))::smallint = 1 statement. > The majority of the time appears to be taken up on the actual INSERT > and not the SELECT part. > > How many rows are in the target table and what indexes does it have? > Does it have any triggers, check constraints, or rules applied to it? > All these things can make the insert take longer as the number of > rows you have already in the table increases. > > More than likely you have a target table with a LOT of rows and a > bunch of indexes on it and your disks are being thrashed because the > indexes are not able to stay cached in RAM. At this point you should > ensure your machine is not swapping do disk, and at the very least > you should go through one of the many tuning guidelines available and > ensure you have allocated the appropriate amount of memory to > postgresql for your needs. > > You may also want to consider dropping the indexes before you do the > INSERT and recreate them afterwards. > > > > "Christian Rengstl" <[EMAIL PROTECTED]> > 13.07.06 8.37 Uhr >>> >> Good morning list, >> >> the following query takes about 15 to 20 minutes for around 2 >> million lines in the file myfile.txt, but with 8 million lines it >> takes around 5 hours and i just don't understand why there is such >> a huge discrepancy in performance. >> >> COPY public.temp_table FROM 'myfile.txt' WITH DELIMITER '\t'; >> >> INSERT INTO public.master(pid,smid, val1, val2, chr) >> SELECT pid, smid, val1, val12, CAST(split_part((SELECT >> chr from public.temp_table LIMIT 1), '_', 2) as int2) >>FROM public.temp_table; >> >> INSERT INTO public.values(smid, pos, chr) >> SELECT DISTINCT smid, pos, CAST(split_part((SELECT chr from >> public.temp_table LIMIT 1), '_', 2) as int2) >> FROM public.temp_table; >> >> I came up with this query, because i wanted to use the COPY command >> to load huge files into the db, but i don't want to load all the >> columns contained in the file in only one table but copy some of >> them into one table and some in a second table. As i found out with >> logging, the data is loaded into temp_table within 15 minutes, but >> to transfer it from the temp_table toagain only something like 10 >> minutes. Can it be that the cast takes up so much more time than >> when reading and transferring 2 million lines? > > > -- > Seeya...Q > > -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- > >_ / Quinton Dolan - [EMAIL PROTECTED] >__ __/ / / __/ / / > /__ / _// /Gold Coast, QLD, Australia >__/ __/ __/ / / - /Ph: +61 419 729 806 > ___ / > _\ > > > > > ---(end of broadcast)--- > TIP 2: Don't 'kill -9' the postmaster -- Christian Rengstl M.A. Klinik und Poliklinik für Innere Medizin II Kardiologie - Forschung Universitätsklinikum Regensburg B3 1.388 Franz-Josef-Strauss-Allee 11 930
Re: [GENERAL] Performance problem with query
On 19/07/2006, at 6:32 PM, Christian Rengstl wrote: The analyze is from the exact query and i dropped the indexes before the insert as well without imrpvement. The target table is as well completely empty and the insert is supposed to write, in this case, more or less 8 million lines in the table. There is a rule though, because i have inheritance table structure with one master table and around 20 child tables. I would say the problem is in the rule. Try doing the insert into a duplicate table with no rules or inheritance and see how long it takes. Perhaps you should provide the actual schema of tables and rules that are involved in the query in question. Q <[EMAIL PROTECTED]> wrote on 07/19/06 4:37 am: On 19/07/2006, at 4:24 AM, Christian Rengstl wrote: now finally after a long time i have the query plan for the whole filled table. I hope somebody can explain me why it takes so much longer... These explain analyze results don't appear to be from the queries you posted previously. For these results to mean anything you need to include the EXACT queries you used to generate them. Result (cost=0.06..254643.06 rows=8044000 width=39) (actual time=0.056..655772 .273 rows=8044000 loops=1) One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 1) InitPlan -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.003..0.003 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.002..0.002 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.006..0.007 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.004..0.004 rows=1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) (act ual time=0.002..191672.344 rows=8044000 loops=1) Total runtime: 62259544.896 ms This is the query you want to be interested in, the others took no time at all. As a guess I would say the query is an INSERT INTO ... FROM SELECT ... WHERE (split_part(???, '_', 2))::smallint = 1 statement. The majority of the time appears to be taken up on the actual INSERT and not the SELECT part. How many rows are in the target table and what indexes does it have? Does it have any triggers, check constraints, or rules applied to it? All these things can make the insert take longer as the number of rows you have already in the table increases. More than likely you have a target table with a LOT of rows and a bunch of indexes on it and your disks are being thrashed because the indexes are not able to stay cached in RAM. At this point you should ensure your machine is not swapping do disk, and at the very least you should go through one of the many tuning guidelines available and ensure you have allocated the appropriate amount of memory to postgresql for your needs. You may also want to consider dropping the indexes before you do the INSERT and recreate them afterwards. "Christian Rengstl" <[EMAIL PROTECTED]> 13.07.06 8.37 Uhr >>> Good morning list, the following query takes about 15 to 20 minutes for around 2 million lines in the file myfile.txt, but with 8 million lines it takes around 5 hours and i just don't understand why there is such a huge discrepancy in performance. COPY public.temp_table FROM 'myfile.txt' WITH DELIMITER '\t'; INSERT INTO public.master(pid,smid, val1, val2, chr) SELECT pid, smid, val1, val12, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; INSERT INTO public.values(smid, pos, chr) SELECT DISTINCT smid, pos, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; I came up with this query, because i wanted to use the COPY command to load huge files into the db, but i don't want to load all the columns contained in the file in only one table but copy some of them into one table and some in a second table. As i found out with logging, the data is loaded into temp_table within 15 minutes, but to transfer it from the temp_table toagain only something like 10 minutes. Can it be that the cast takes up so much more time than when reading and transferring 2 million lines? -- Seeya...Q -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- _ / Quinton Dolan - [EMAIL PROTECTED] __ __/ / / __/ / / /__ / _// /Gold Coast, QLD, Australia __/ __/ __/ / / - /Ph: +61 419 729 806 ___ / _\ ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster -- Christian Rengstl M.A. Klinik und Poliklinik für Innere Medizin II Kardiologie - Forschung Universitätsklinikum Regensburg B3 1.388 Franz-Josef-Strauss-Allee 11 93053 Regensburg Tel.: +
Re: [GENERAL] Performance problem with query
Well, i'll try that, but honestly i don't think it's the rule as the rule is really simple: it's just one simple integer comparison... Q <[EMAIL PROTECTED]> wrote on 07/19/06 11:54 am: > On 19/07/2006, at 6:32 PM, Christian Rengstl wrote: > >> The analyze is from the exact query and i dropped the indexes >> before the insert as well without imrpvement. The target table is >> as well completely empty and the insert is supposed to write, in >> this case, more or less 8 million lines in the table. There is a >> rule though, because i have inheritance table structure with one >> master table and around 20 child tables. > > I would say the problem is in the rule. Try doing the insert into a > duplicate table with no rules or inheritance and see how long it takes. > > Perhaps you should provide the actual schema of tables and rules that > are involved in the query in question. > >> Q <[EMAIL PROTECTED]> wrote on 07/19/06 4:37 am: >>> >>> On 19/07/2006, at 4:24 AM, Christian Rengstl wrote: >>> now finally after a long time i have the query plan for the whole filled table. I hope somebody can explain me why it takes so much longer... >>> >>> >>> These explain analyze results don't appear to be from the queries you >>> posted previously. For these results to mean anything you need to >>> include the EXACT queries you used to generate them. >>> Result (cost=0.06..254643.06 rows=8044000 width=39) (actual time=0.056..655772 .273 rows=8044000 loops=1) One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 1) InitPlan -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.003..0.003 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.002..0.002 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.006..0.007 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.004..0.004 rows=1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) (act ual time=0.002..191672.344 rows=8044000 loops=1) Total runtime: 62259544.896 ms >>> >>> >>> This is the query you want to be interested in, the others took no >>> time at all. >>> >>> As a guess I would say the query is an INSERT INTO ... FROM >>> SELECT ... WHERE (split_part(???, '_', 2))::smallint = 1 statement. >>> The majority of the time appears to be taken up on the actual INSERT >>> and not the SELECT part. >>> >>> How many rows are in the target table and what indexes does it have? >>> Does it have any triggers, check constraints, or rules applied to it? >>> All these things can make the insert take longer as the number of >>> rows you have already in the table increases. >>> >>> More than likely you have a target table with a LOT of rows and a >>> bunch of indexes on it and your disks are being thrashed because the >>> indexes are not able to stay cached in RAM. At this point you should >>> ensure your machine is not swapping do disk, and at the very least >>> you should go through one of the many tuning guidelines available and >>> ensure you have allocated the appropriate amount of memory to >>> postgresql for your needs. >>> >>> You may also want to consider dropping the indexes before you do the >>> INSERT and recreate them afterwards. >>> >>> >>> >>> "Christian Rengstl" <[EMAIL PROTECTED]> >>> 13.07.06 8.37 Uhr >>> Good morning list, the following query takes about 15 to 20 minutes for around 2 million lines in the file myfile.txt, but with 8 million lines it takes around 5 hours and i just don't understand why there is such a huge discrepancy in performance. COPY public.temp_table FROM 'myfile.txt' WITH DELIMITER '\t'; INSERT INTO public.master(pid,smid, val1, val2, chr) SELECT pid, smid, val1, val12, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; INSERT INTO public.values(smid, pos, chr) SELECT DISTINCT smid, pos, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; I came up with this query, because i wanted to use the COPY command to load huge files into the db, but i don't want to load all the columns contained in the file in only one table but copy some of them into one table and some in a second table. As i found out with logging, the data is loaded into temp_table within 15 minutes, but to transfer it from the temp_table toagain only something like 10 minutes. Can it be that the cast takes up so much more time than when reading and transferring 2 million lines? >>> >>> >>> -- >>> Seeya...Q >>> >>> -=-=-=-=-=-=-=-=-=-=-=
Re: [GENERAL] Performance problem with query
Obviously it had something to do with the rule, because now everything finished within 20 minutes. the problem is just that i don't really want to give up the inheritance design. is there a way to maintain the inheritance that doesn't cause this huge performance problem? Q <[EMAIL PROTECTED]> wrote on 07/19/06 11:54 am: > On 19/07/2006, at 6:32 PM, Christian Rengstl wrote: > >> The analyze is from the exact query and i dropped the indexes >> before the insert as well without imrpvement. The target table is >> as well completely empty and the insert is supposed to write, in >> this case, more or less 8 million lines in the table. There is a >> rule though, because i have inheritance table structure with one >> master table and around 20 child tables. > > I would say the problem is in the rule. Try doing the insert into a > duplicate table with no rules or inheritance and see how long it takes. > > Perhaps you should provide the actual schema of tables and rules that > are involved in the query in question. > >> Q <[EMAIL PROTECTED]> wrote on 07/19/06 4:37 am: >>> >>> On 19/07/2006, at 4:24 AM, Christian Rengstl wrote: >>> now finally after a long time i have the query plan for the whole filled table. I hope somebody can explain me why it takes so much longer... >>> >>> >>> These explain analyze results don't appear to be from the queries you >>> posted previously. For these results to mean anything you need to >>> include the EXACT queries you used to generate them. >>> Result (cost=0.06..254643.06 rows=8044000 width=39) (actual time=0.056..655772 .273 rows=8044000 loops=1) One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 1) InitPlan -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.003..0.003 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.002..0.002 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.006..0.007 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.004..0.004 rows=1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) (act ual time=0.002..191672.344 rows=8044000 loops=1) Total runtime: 62259544.896 ms >>> >>> >>> This is the query you want to be interested in, the others took no >>> time at all. >>> >>> As a guess I would say the query is an INSERT INTO ... FROM >>> SELECT ... WHERE (split_part(???, '_', 2))::smallint = 1 statement. >>> The majority of the time appears to be taken up on the actual INSERT >>> and not the SELECT part. >>> >>> How many rows are in the target table and what indexes does it have? >>> Does it have any triggers, check constraints, or rules applied to it? >>> All these things can make the insert take longer as the number of >>> rows you have already in the table increases. >>> >>> More than likely you have a target table with a LOT of rows and a >>> bunch of indexes on it and your disks are being thrashed because the >>> indexes are not able to stay cached in RAM. At this point you should >>> ensure your machine is not swapping do disk, and at the very least >>> you should go through one of the many tuning guidelines available and >>> ensure you have allocated the appropriate amount of memory to >>> postgresql for your needs. >>> >>> You may also want to consider dropping the indexes before you do the >>> INSERT and recreate them afterwards. >>> >>> >>> >>> "Christian Rengstl" <[EMAIL PROTECTED]> >>> 13.07.06 8.37 Uhr >>> Good morning list, the following query takes about 15 to 20 minutes for around 2 million lines in the file myfile.txt, but with 8 million lines it takes around 5 hours and i just don't understand why there is such a huge discrepancy in performance. COPY public.temp_table FROM 'myfile.txt' WITH DELIMITER '\t'; INSERT INTO public.master(pid,smid, val1, val2, chr) SELECT pid, smid, val1, val12, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; INSERT INTO public.values(smid, pos, chr) SELECT DISTINCT smid, pos, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; I came up with this query, because i wanted to use the COPY command to load huge files into the db, but i don't want to load all the columns contained in the file in only one table but copy some of them into one table and some in a second table. As i found out with logging, the data is loaded into temp_table within 15 minutes, but to transfer it from the temp_table toagain only something like 10 minutes. Can it be that the cast takes up so much more
Re: [GENERAL] Performance problem with query
On 19/07/2006, at 8:49 PM, Christian Rengstl wrote: Obviously it had something to do with the rule, because now everything finished within 20 minutes. the problem is just that i don't really want to give up the inheritance design. is there a way to maintain the inheritance that doesn't cause this huge performance problem? That is hard to say unless you post the rule and table schema you are currently using. Q <[EMAIL PROTECTED]> wrote on 07/19/06 11:54 am: On 19/07/2006, at 6:32 PM, Christian Rengstl wrote: The analyze is from the exact query and i dropped the indexes before the insert as well without imrpvement. The target table is as well completely empty and the insert is supposed to write, in this case, more or less 8 million lines in the table. There is a rule though, because i have inheritance table structure with one master table and around 20 child tables. I would say the problem is in the rule. Try doing the insert into a duplicate table with no rules or inheritance and see how long it takes. Perhaps you should provide the actual schema of tables and rules that are involved in the query in question. Q <[EMAIL PROTECTED]> wrote on 07/19/06 4:37 am: On 19/07/2006, at 4:24 AM, Christian Rengstl wrote: now finally after a long time i have the query plan for the whole filled table. I hope somebody can explain me why it takes so much longer... These explain analyze results don't appear to be from the queries you posted previously. For these results to mean anything you need to include the EXACT queries you used to generate them. Result (cost=0.06..254643.06 rows=8044000 width=39) (actual time=0.056..655772 .273 rows=8044000 loops=1) One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 1) InitPlan -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.003..0.003 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.002..0.002 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.006..0.007 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.004..0.004 rows=1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) (act ual time=0.002..191672.344 rows=8044000 loops=1) Total runtime: 62259544.896 ms This is the query you want to be interested in, the others took no time at all. As a guess I would say the query is an INSERT INTO ... FROM SELECT ... WHERE (split_part(???, '_', 2))::smallint = 1 statement. The majority of the time appears to be taken up on the actual INSERT and not the SELECT part. How many rows are in the target table and what indexes does it have? Does it have any triggers, check constraints, or rules applied to it? All these things can make the insert take longer as the number of rows you have already in the table increases. More than likely you have a target table with a LOT of rows and a bunch of indexes on it and your disks are being thrashed because the indexes are not able to stay cached in RAM. At this point you should ensure your machine is not swapping do disk, and at the very least you should go through one of the many tuning guidelines available and ensure you have allocated the appropriate amount of memory to postgresql for your needs. You may also want to consider dropping the indexes before you do the INSERT and recreate them afterwards. "Christian Rengstl" <[EMAIL PROTECTED] regensburg.de> 13.07.06 8.37 Uhr >>> Good morning list, the following query takes about 15 to 20 minutes for around 2 million lines in the file myfile.txt, but with 8 million lines it takes around 5 hours and i just don't understand why there is such a huge discrepancy in performance. COPY public.temp_table FROM 'myfile.txt' WITH DELIMITER '\t'; INSERT INTO public.master(pid,smid, val1, val2, chr) SELECT pid, smid, val1, val12, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; INSERT INTO public.values(smid, pos, chr) SELECT DISTINCT smid, pos, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; I came up with this query, because i wanted to use the COPY command to load huge files into the db, but i don't want to load all the columns contained in the file in only one table but copy some of them into one table and some in a second table. As i found out with logging, the data is loaded into temp_table within 15 minutes, but to transfer it from the temp_table toagain only something like 10 minutes. Can it be that the cast takes up so much more time than when reading and transferring 2 million lines? -- Seeya...Q -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- _ / Quinton Dolan - [EMAIL PROTECTED] __ __/ / / __/
Re: [GENERAL] Performance problem with query
So here's the master table including the rules:
entry_no int8 NOT NULL DEFAULT nextval('public.master_seq'::regclass),
pid varchar(15) NOT NULL,
val_1 varchar(1),
val_2 varchar(1),
chr int2 NOT NULL,
aendat timestamp DEFAULT now(),
aennam varchar(8),
CONSTRAINT "PK_ENTRY" PRIMARY KEY (entry_no),
CONSTRAINT "UNIQUE_MASTER" UNIQUE (pid, entry_no)
CREATE OR REPLACE RULE "INSERT_INTO_1" AS
ON INSERT TO public.master
WHERE new.chr = 1 DO INSTEAD INSERT INTO public.table_1 (entry_no, pid,
val_1, val_2, chr, aendat, aennam)
VALUES (new.entry_no, new.pid, new.val_1, new.val_2, new.chr, new.aendat,
new.aennam);
Like this i have around 20 rules so far, but there might be more later on. The
children tables are so far exactly as the master table.
Q <[EMAIL PROTECTED]> wrote on 07/19/06 1:52 pm:
> On 19/07/2006, at 8:49 PM, Christian Rengstl wrote:
>
>> Obviously it had something to do with the rule, because now
>> everything finished within 20 minutes. the problem is just that i
>> don't really want to give up the inheritance design. is there a way
>> to maintain the inheritance that doesn't cause this huge
>> performance problem?
>
> That is hard to say unless you post the rule and table schema you are
> currently using.
>
>> Q <[EMAIL PROTECTED]> wrote on 07/19/06 11:54 am:
>>> On 19/07/2006, at 6:32 PM, Christian Rengstl wrote:
>>>
The analyze is from the exact query and i dropped the indexes
before the insert as well without imrpvement. The target table is
as well completely empty and the insert is supposed to write, in
this case, more or less 8 million lines in the table. There is a
rule though, because i have inheritance table structure with one
master table and around 20 child tables.
>>>
>>> I would say the problem is in the rule. Try doing the insert into a
>>> duplicate table with no rules or inheritance and see how long it
>>> takes.
>>>
>>> Perhaps you should provide the actual schema of tables and rules that
>>> are involved in the query in question.
>>>
Q <[EMAIL PROTECTED]> wrote on 07/19/06 4:37 am:
>
> On 19/07/2006, at 4:24 AM, Christian Rengstl wrote:
>
>> now finally after a long time i have the query plan for the whole
>> filled table. I hope somebody can explain me why it takes so much
>> longer...
>
>
> These explain analyze results don't appear to be from the
> queries you
> posted previously. For these results to mean anything you need to
> include the EXACT queries you used to generate them.
>
>> Result (cost=0.06..254643.06 rows=8044000 width=39) (actual
>> time=0.056..655772
>> .273 rows=8044000 loops=1)
>> One-Time Filter: ((split_part(($1)::text, '_'::text,
>> 2))::smallint = 1)
>> InitPlan
>> -> Limit (cost=0.00..0.02 rows=1 width=10) (actual
>> time=0.003..0.003 rows
>> =1 loops=1)
>> -> Seq Scan on temp_table (cost=0.00..194313.00
>> rows=8044000 width=
>> 10) (actual time=0.002..0.002 rows=1 loops=1)
>> -> Limit (cost=0.00..0.02 rows=1 width=10) (actual
>> time=0.006..0.007 rows
>> =1 loops=1)
>> -> Seq Scan on temp_table (cost=0.00..194313.00
>> rows=8044000 width=
>> 10) (actual time=0.004..0.004 rows=1 loops=1)
>> -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000
>> width=39) (act
>> ual time=0.002..191672.344 rows=8044000 loops=1)
>> Total runtime: 62259544.896 ms
>
>
> This is the query you want to be interested in, the others took no
> time at all.
>
> As a guess I would say the query is an INSERT INTO ... FROM
> SELECT ... WHERE (split_part(???, '_', 2))::smallint = 1 statement.
> The majority of the time appears to be taken up on the actual
> INSERT
> and not the SELECT part.
>
> How many rows are in the target table and what indexes does it
> have?
> Does it have any triggers, check constraints, or rules applied
> to it?
> All these things can make the insert take longer as the number of
> rows you have already in the table increases.
>
> More than likely you have a target table with a LOT of rows and a
> bunch of indexes on it and your disks are being thrashed because
> the
> indexes are not able to stay cached in RAM. At this point you
> should
> ensure your machine is not swapping do disk, and at the very least
> you should go through one of the many tuning guidelines
> available and
> ensure you have allocated the appropriate amount of memory to
> postgresql for your needs.
>
> You may also want to consider dropping the indexes before you do
> the
> INSERT and recreate them afterwards.
>
>
>
> "Christian Rengstl" <[EMAIL PROTECTED]
> regensburg.de>
> 13.07.06 8.37 Uhr >>>
>> Good morning list,
>>
>> the fo
Re: [GENERAL] Performance problem with query
On 19/07/2006, at 10:03 PM, Christian Rengstl wrote:
So here's the master table including the rules:
entry_no int8 NOT NULL DEFAULT nextval('public.master_seq'::regclass),
pid varchar(15) NOT NULL,
val_1 varchar(1),
val_2 varchar(1),
chr int2 NOT NULL,
aendat timestamp DEFAULT now(),
aennam varchar(8),
CONSTRAINT "PK_ENTRY" PRIMARY KEY (entry_no),
CONSTRAINT "UNIQUE_MASTER" UNIQUE (pid, entry_no)
CREATE OR REPLACE RULE "INSERT_INTO_1" AS
ON INSERT TO public.master
WHERE new.chr = 1 DO INSTEAD INSERT INTO public.table_1
(entry_no, pid, val_1, val_2, chr, aendat, aennam)
VALUES (new.entry_no, new.pid, new.val_1, new.val_2, new.chr,
new.aendat, new.aennam);
Like this i have around 20 rules so far, but there might be more
later on. The children tables are so far exactly as the master table.
What about the children? Do they have the same indexes?
You could try adding an 'ORDER BY chr' to your long running INSERT
INTO ... SELECT ... query.
Obviously it had something to do with the rule, because now
everything finished within 20 minutes. the problem is just that i
don't really want to give up the inheritance design. is there a way
to maintain the inheritance that doesn't cause this huge
performance problem?
When you say "now everything finished within 20 minutes", what did
you actually do to achieve this?
--
Seeya...Q
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
_ / Quinton Dolan - [EMAIL PROTECTED]
__ __/ / / __/ / /
/__ / _// /Gold Coast, QLD, Australia
__/ __/ __/ / / - /Ph: +61 419 729 806
___ /
_\
---(end of broadcast)---
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Antw: Re: [GENERAL] Performance problem with query
Hi, somehow my reply yesterday got lost, but nevertheless here comes the explain analyze again. It's the explain of the operation that causes this huge performance discrepancy. Unfortunately i had to perform the explain analyze with an empty temp_table, because after the whole operation is done, i delete the data again to save some space. QUE RY PLAN - Result (cost=0.12..16.95 rows=390 width=108) (actual time=0.025..0.025 rows=0 loops=1) One-Time Filter: split_part(($1)::text, '_'::text, 2))::smallint = 1) IS NOT TRUE) AND (((split_part(($2)::text, '_'::text, 2))::smallint = 22) IS NOT TR UE)) InitPlan -> Limit (cost=0.00..0.04 rows=1 width=28) (never executed) -> Seq Scan on temp_table (cost=0.00..13.90 rows=390 width=28) (nev er executed) -> Limit (cost=0.00..0.04 rows=1 width=28) (actual time=0.005..0.005 rows =0 loops=1) -> Seq Scan on temp_table (cost=0.00..13.90 rows=390 width=28) (act ual time=0.001..0.001 rows=0 loops=1) -> Limit (cost=0.00..0.04 rows=1 width=28) (actual time=0.002..0.002 rows =0 loops=1) -> Seq Scan on temp_table (cost=0.00..13.90 rows=390 width=28) (act ual time=0.000..0.000 rows=0 loops=1) -> Seq Scan on temp_table (cost=0.00..13.90 rows=390 width=108) (actual tim e=0.000..0.000 rows=0 loops=1) Total runtime: 0.424 ms Result (cost=0.08..16.90 rows=390 width=108) (actual time=0.005..0.005 rows=0 loops=1) One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 1) InitPlan -> Limit (cost=0.00..0.04 rows=1 width=28) (never executed) -> Seq Scan on temp_table (cost=0.00..13.90 rows=390 width=28) (nev er executed) -> Limit (cost=0.00..0.04 rows=1 width=28) (actual time=0.002..0.002 rows =0 loops=1) -> Seq Scan on temp_table (cost=0.00..13.90 rows=390 width=28) (act ual time=0.001..0.001 rows=0 loops=1) -> Seq Scan on temp_table (cost=0.00..13.90 rows=390 width=108) (never exec uted) Total runtime: 0.267 ms Result (cost=0.08..16.90 rows=390 width=108) (actual time=0.005..0.005 rows=0 loops=1) One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 22) InitPlan -> Limit (cost=0.00..0.04 rows=1 width=28) (never executed) -> Seq Scan on temp_table (cost=0.00..13.90 rows=390 width=28) (nev er executed) -> Limit (cost=0.00..0.04 rows=1 width=28) (actual time=0.002..0.002 rows =0 loops=1) -> Seq Scan on temp_table (cost=0.00..13.90 rows=390 width=28) (act ual time=0.001..0.001 rows=0 loops=1) -> Seq Scan on temp_table (cost=0.00..13.90 rows=390 width=108) (never exec uted) Total runtime: 0.189 ms (31 Zeilen) ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster
Antw: Re: [GENERAL] Performance problem with query
now finally after a long time i have the query plan for the whole filled table. I hope somebody can explain me why it takes so much longer... QUERY PLAN - Result (cost=0.09..254643.09 rows=8044000 width=39) (actual time=0.043..0.043 rows=0 loops=1) One-Time Filter: split_part(($1)::text, '_'::text, 2))::smallint = 1) IS NOT TRUE) AND (((split_part(($2)::text, '_'::text, 2))::smallint = 22) IS NOT TR UE)) InitPlan -> Limit (cost=0.00..0.02 rows=1 width=10) (never executed) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (never executed) -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.006..0.006 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.004..0.004 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=10) (never executed) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (never executed) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) (nev er executed) Total runtime: 0.238 ms Result (cost=0.06..254643.06 rows=8044000 width=39) (actual time=0.056..655772 .273 rows=8044000 loops=1) One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 1) InitPlan -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.003..0.003 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.002..0.002 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.006..0.007 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.004..0.004 rows=1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) (act ual time=0.002..191672.344 rows=8044000 loops=1) Total runtime: 62259544.896 ms Result (cost=0.06..254643.06 rows=8044000 width=39) (actual time=1.245..1.245 rows=0 loops=1) One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 22) InitPlan -> Limit (cost=0.00..0.02 rows=1 width=10) (never executed) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (never executed) -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.013..0.014 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.009..0.009 rows=1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) (nev er executed) Total runtime: 22.270 ms (31 Zeilen) >>> "Merlin Moncure" <[EMAIL PROTECTED]> 13.07.06 15.20 Uhr >>> On 7/13/06, Christian Rengstl <[EMAIL PROTECTED]> wrote: > Good morning list, > > the following query takes about 15 to 20 minutes for around 2 million lines in the file myfile.txt, but with 8 million lines it takes around 5 hours and i just don't understand why there is such a huge discrepancy in performance. on the surface it doesn't make sense, can you post an explain analyze? merlin ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster >>> "Merlin Moncure" <[EMAIL PROTECTED]> 13.07.06 15.20 Uhr >>> On 7/13/06, Christian Rengstl <[EMAIL PROTECTED]> wrote: > Good morning list, > > the following query takes about 15 to 20 minutes for around 2 million lines in the file myfile.txt, but with 8 million lines it takes around 5 hours and i just don't understand why there is such a huge discrepancy in performance. on the surface it doesn't make sense, can you post an explain analyze? merlin ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster ---(end of broadcast)--- TIP 5: don't forget to increase your free space map settings
Re: Antw: [GENERAL] Performance problem with query
On 19/07/2006, at 4:24 AM, Christian Rengstl wrote: now finally after a long time i have the query plan for the whole filled table. I hope somebody can explain me why it takes so much longer... These explain analyze results don't appear to be from the queries you posted previously. For these results to mean anything you need to include the EXACT queries you used to generate them. Result (cost=0.06..254643.06 rows=8044000 width=39) (actual time=0.056..655772 .273 rows=8044000 loops=1) One-Time Filter: ((split_part(($1)::text, '_'::text, 2))::smallint = 1) InitPlan -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.003..0.003 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.002..0.002 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=10) (actual time=0.006..0.007 rows =1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width= 10) (actual time=0.004..0.004 rows=1 loops=1) -> Seq Scan on temp_table (cost=0.00..194313.00 rows=8044000 width=39) (act ual time=0.002..191672.344 rows=8044000 loops=1) Total runtime: 62259544.896 ms This is the query you want to be interested in, the others took no time at all. As a guess I would say the query is an INSERT INTO ... FROM SELECT ... WHERE (split_part(???, '_', 2))::smallint = 1 statement. The majority of the time appears to be taken up on the actual INSERT and not the SELECT part. How many rows are in the target table and what indexes does it have? Does it have any triggers, check constraints, or rules applied to it? All these things can make the insert take longer as the number of rows you have already in the table increases. More than likely you have a target table with a LOT of rows and a bunch of indexes on it and your disks are being thrashed because the indexes are not able to stay cached in RAM. At this point you should ensure your machine is not swapping do disk, and at the very least you should go through one of the many tuning guidelines available and ensure you have allocated the appropriate amount of memory to postgresql for your needs. You may also want to consider dropping the indexes before you do the INSERT and recreate them afterwards. "Christian Rengstl" <[EMAIL PROTECTED]> 13.07.06 8.37 Uhr >>> Good morning list, the following query takes about 15 to 20 minutes for around 2 million lines in the file myfile.txt, but with 8 million lines it takes around 5 hours and i just don't understand why there is such a huge discrepancy in performance. COPY public.temp_table FROM 'myfile.txt' WITH DELIMITER '\t'; INSERT INTO public.master(pid,smid, val1, val2, chr) SELECT pid, smid, val1, val12, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; INSERT INTO public.values(smid, pos, chr) SELECT DISTINCT smid, pos, CAST(split_part((SELECT chr from public.temp_table LIMIT 1), '_', 2) as int2) FROM public.temp_table; I came up with this query, because i wanted to use the COPY command to load huge files into the db, but i don't want to load all the columns contained in the file in only one table but copy some of them into one table and some in a second table. As i found out with logging, the data is loaded into temp_table within 15 minutes, but to transfer it from the temp_table toagain only something like 10 minutes. Can it be that the cast takes up so much more time than when reading and transferring 2 million lines? -- Seeya...Q -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- _ / Quinton Dolan - [EMAIL PROTECTED] __ __/ / / __/ / / /__ / _// /Gold Coast, QLD, Australia __/ __/ __/ / / - /Ph: +61 419 729 806 ___ / _\ ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster
