Обсуждение: Antw: 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
takesso 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" <Christian.Rengstl@klinik.uni-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
linesit 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
loadall 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_tabletoagain only something like 10 minutes. Can it be that the cast takes up so much more time than when reading
andtransferring 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
On 7/18/06, Christian Rengstl <Christian.Rengstl@klinik.uni-regensburg.de> 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 takesso 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" <Christian.Rengstl@klinik.uni-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 millionlines 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
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" <Christian.Rengstl@klinik.uni-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 - qdolan@gmail.com
__ __/ / / __/ / /
/ __ / _/ / / Gold Coast, QLD, Australia
__/ __/ __/ ____/ / - / Ph: +61 419 729 806
_______ /
_\
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 integerpart of it that's what the query is used for. The problem though is not really in the select part, because runningthe select part on 8 million lines takes about 3 minutes, but i don't know why the insert is taking so long. "Merlin Moncure" <mmoncure@gmail.com> wrote on 07/18/06 9:39 pm: > On 7/18/06, Christian Rengstl > <Christian.Rengstl@klinik.uni-regensburg.de> wrote: >> now finally after a long time i have the query plan for the whole filled table. I hope somebody can explain me why ittakes 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" <Christian.Rengstl@klinik.uni-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 millionlines 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
The analyze is from the exact query and i dropped the indexes before the insert as well without imrpvement. The target tableis 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 <qdolan@gmail.com> 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" <Christian.Rengstl@klinik.uni-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 - qdolan@gmail.com > __ __/ / / __/ / / > / __ / _/ / / 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.: +49-941-944-7230
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 <qdolan@gmail.com> 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" <Christian.Rengstl@klinik.uni-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 - qdolan@gmail.com
>> __ __/ / / __/ / /
>> / __ / _/ / / 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.: +49-941-944-7230
--
Seeya...Q
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
_____ / Quinton Dolan - qdolan@gmail.com
__ __/ / / __/ / /
/ __ / _/ / / Gold Coast, QLD, Australia
__/ __/ __/ ____/ / - / Ph: +61 419 729 806
_______ /
_\
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 integercomparison... Q <qdolan@gmail.com> 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 <qdolan@gmail.com> 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" <Christian.Rengstl@klinik.uni-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 - qdolan@gmail.com >>> __ __/ / / __/ / / >>> / __ / _/ / / 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.: +49-941-944-7230 > > > -- > Seeya...Q > > -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- > > _____ / Quinton Dolan - qdolan@gmail.com > __ __/ / / __/ / / > / __ / _/ / / Gold Coast, QLD, Australia > __/ __/ __/ ____/ / - / Ph: +61 419 729 806 > _______ / > _\ > > -- 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
Obviously it had something to do with the rule, because now everything finished within 20 minutes. the problem is just thati don't really want to give up the inheritance design. is there a way to maintain the inheritance that doesn't causethis huge performance problem? Q <qdolan@gmail.com> 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 <qdolan@gmail.com> 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" <Christian.Rengstl@klinik.uni-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 - qdolan@gmail.com >>> __ __/ / / __/ / / >>> / __ / _/ / / 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.: +49-941-944-7230 > > > -- > Seeya...Q > > -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- > > _____ / Quinton Dolan - qdolan@gmail.com > __ __/ / / __/ / / > / __ / _/ / / Gold Coast, QLD, Australia > __/ __/ __/ ____/ / - / Ph: +61 419 729 806 > _______ / > _\ > > -- 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
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 <qdolan@gmail.com> 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 <qdolan@gmail.com> 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" <Christian.Rengstl@klinik.uni-
>>>>>>>> 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 -
>>>> qdolan@gmail.com
>>>> __ __/ / / __/ / /
>>>> / __ / _/ / / 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.: +49-941-944-7230
>>
>>
>> --
>> Seeya...Q
>>
>> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>>
>> _____ / Quinton Dolan - qdolan@gmail.com
>> __ __/ / / __/ / /
>> / __ / _/ / / Gold Coast, QLD, Australia
>> __/ __/ __/ ____/ / - / Ph: +61 419 729 806
>> _______ /
>> _\
>>
>>
>
>
> --
> 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
--
Seeya...Q
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
_____ / Quinton Dolan - qdolan@gmail.com
__ __/ / / __/ / /
/ __ / _/ / / Gold Coast, QLD, Australia
__/ __/ __/ ____/ / - / Ph: +61 419 729 806
_______ /
_\
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
themaster table.
Q <qdolan@gmail.com> 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 <qdolan@gmail.com> 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 <qdolan@gmail.com> 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" <Christian.Rengstl@klinik.uni-
>>>>>>>>> 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 -
>>>>> qdolan@gmail.com
>>>>> __ __/ / / __/ / /
>>>>> / __ / _/ / / 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.: +49-941-944-7230
>>>
>>>
>>> --
>>> Seeya...Q
>>>
>>> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>>>
>>> _____ / Quinton Dolan - qdolan@gmail.com
>>> __ __/ / / __/ / /
>>> / __ / _/ / / Gold Coast, QLD, Australia
>>> __/ __/ __/ ____/ / - / Ph: +61 419 729 806
>>> _______ /
>>> _\
>>>
>>>
>>
>>
>> --
>> 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
>
>
> --
> Seeya...Q
>
> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>
> _____ / Quinton Dolan - qdolan@gmail.com
> __ __/ / / __/ / /
> / __ / _/ / / Gold Coast, QLD, Australia
> __/ __/ __/ ____/ / - / Ph: +61 419 729 806
> _______ /
> _\
>
>
--
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
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 - qdolan@gmail.com
__ __/ / / __/ / /
/ __ / _/ / / Gold Coast, QLD, Australia
__/ __/ __/ ____/ / - / Ph: +61 419 729 806
_______ /
_\