Hi,
Has anyone got problem with this on large table. It seems it take ages to return the result ( half an hour :-( ).
SELECT COUNT(*) FROM COORDINATE
A strange thing is the tempory space (System Managed) keeps growing during the query:
14346747904 Dec 2 16:22 SQL00002.TDA
It's almost as large as the current table (17GB). Any comments?
Many thanks,
Bing 12 39615
Bing Wu wrote: Hi,
Has anyone got problem with this on large table. It seems it take ages to return the result ( half an hour :-( ).
SELECT COUNT(*) FROM COORDINATE
A strange thing is the tempory space (System Managed) keeps growing during the query:
14346747904 Dec 2 16:22 SQL00002.TDA
It's almost as large as the current table (17GB). Any comments?
Many thanks,
Bing
try:
select count(1) from ...
and see.
hth.
Wolfgang
Many thanks for the hint. It seems still taking long time.
Bing
Wolfgang Riedel wrote: try:
select count(1) from ...
and see.
hth. Wolfgang
>Has anyone got problem with this on large table. It seems it take ages to return the result ( half an hour :-( ).
SELECT COUNT(*) FROM COORDINATE
have you ran explain ? maybe an index would help
Is there any index for the table?
Maybe you should reorg the TS and Indexspace to optimize it.
Form the result count, it's a huge table, if it's not well orgnized, it'll
need a long time to get a result of course.
"Bing Wu" <bi**@biop.ox.ac.uk> wrote in message
news:bq**********@news.ox.ac.uk... Hi,
Has anyone got problem with this on large table. It seems it take ages to
return the result ( half an hour :-( ). SELECT COUNT(*) FROM COORDINATE
A strange thing is the tempory space (System Managed) keeps growing during
the query: 14346747904 Dec 2 16:22 SQL00002.TDA
It's almost as large as the current table (17GB). Any comments?
Many thanks,
Bing
Bing Wu wrote: Hi,
Has anyone got problem with this on large table. It seems it take ages to return the result ( half an hour :-( ).
SELECT COUNT(*) FROM COORDINATE
A strange thing is the tempory space (System Managed) keeps growing during the query:
14346747904 Dec 2 16:22 SQL00002.TDA
It's almost as large as the current table (17GB). Any comments?
Many thanks,
Bing
Are you certain that COORDINATE is a table and not a view? Normally
a simple query like this should not require any temp space. As someone
already mentioned in this thread, get an explain for the query. Once
you do, post it here, maybe someone will be able to help you then.
Regards,
Miro
Yes, it's a table with over a billion rows. I have run the SQL explain and please find the result below.
Thanks again,
Bing
Package Name = "DB2ADMIN"."DYNEXPLN" Version = ""
Prep Date = 2003/12/04
Prep Time = 15:36:33
Bind Timestamp = 2003-12-04-15.36.33.960521
Isolation Level = Cursor Stability
Blocking = Block Unambiguous Cursors
Query Optimization Class = 7
Partition Parallel = No
Intra-Partition Parallel = Yes (Bind Degree = ANY)
SQL Path = "SYSIBM", "SYSFUN", "SYSPROC", "DB2ADMIN"
-------------------- SECTION ---------------------------------------
Section = 1
SQL Statement:
DECLARE C1 CURSOR
FOR
SELECT COUNT(*)
FROM COORDINATE
Intra-Partition Parallelism Degree = 2
Section Code Page = 819
Estimated Cost = 8889258.000000
Estimated Cardinality = 1.000000
Process Using 2 Subagents
| Access Table Name = DB2ADMIN.COORDINATE ID = 4,4
| | #Columns = 0
| | Parallel Scan
| | Relation Scan
| | | Prefetch: Eligible
| | Lock Intents
| | | Table: Intent Share
| | | Row : Next Key Share
| | Sargable Predicate(s)
| | | Partial Predicate Aggregation
| | | | Column Function(s)
| Partial Aggregation Completion
| | Column Function(s)
| Insert Into Asynchronous Local Table Queue ID = q1
Access Local Table Queue ID = q1 #Columns = 1
Final Aggregation
| Column Function(s)
Return Data to Application
| #Columns = 1
End of section
miro flasza wrote: Are you certain that COORDINATE is a table and not a view? Normally a simple query like this should not require any temp space. As someone already mentioned in this thread, get an explain for the query. Once you do, post it here, maybe someone will be able to help you then.
Regards, Miro
Yes, it's indexed and organised. I'll try the reorg and see if it improves.
Thanks,
Bing
Jing Li wrote: Is there any index for the table? Maybe you should reorg the TS and Indexspace to optimize it. Form the result count, it's a huge table, if it's not well orgnized, it'll need a long time to get a result of course.
Bing Wu,
do you have any indexes on the table at all?
Have you run reorgchk?
Likely unrelated, but what happens if you do a select count_big(*)
against the table? Have you done a runstats on the table? Runstats on
its indexes? Can you define a unique index on it (sorry if you'd heard
these sugggestions before)?
Bing Wu wrote: Yes, it's indexed and organised. I'll try the reorg and see if it improves.
Thanks,
Bing
Jing Li wrote:
Is there any index for the table? Maybe you should reorg the TS and Indexspace to optimize it. Form the result count, it's a huge table, if it's not well orgnized, it'll need a long time to get a result of course.
Bing, is the access plan with a default query set to 1 the same - relation
scan and not index scan ?
Jean-Marc
"Bing Wu" <bi**@biop.ox.ac.uk> a écrit dans le message de
news:bq**********@news.ox.ac.uk... Yes, it's a table with over a billion rows. I have run the SQL explain and
please find the result below. Thanks again,
Bing
Package Name = "DB2ADMIN"."DYNEXPLN" Version = ""
Prep Date = 2003/12/04 Prep Time = 15:36:33
Bind Timestamp = 2003-12-04-15.36.33.960521
Isolation Level = Cursor Stability Blocking = Block Unambiguous Cursors Query Optimization Class = 7
Partition Parallel = No Intra-Partition Parallel = Yes (Bind Degree = ANY)
SQL Path = "SYSIBM", "SYSFUN", "SYSPROC",
"DB2ADMIN" -------------------- SECTION --------------------------------------- Section = 1
SQL Statement: DECLARE C1 CURSOR FOR SELECT COUNT(*) FROM COORDINATE
Intra-Partition Parallelism Degree = 2
Section Code Page = 819
Estimated Cost = 8889258.000000 Estimated Cardinality = 1.000000
Process Using 2 Subagents | Access Table Name = DB2ADMIN.COORDINATE ID = 4,4 | | #Columns = 0 | | Parallel Scan | | Relation Scan | | | Prefetch: Eligible | | Lock Intents | | | Table: Intent Share | | | Row : Next Key Share | | Sargable Predicate(s) | | | Partial Predicate Aggregation | | | | Column Function(s) | Partial Aggregation Completion | | Column Function(s) | Insert Into Asynchronous Local Table Queue ID = q1 Access Local Table Queue ID = q1 #Columns = 1 Final Aggregation | Column Function(s) Return Data to Application | #Columns = 1
End of section
miro flasza wrote: Are you certain that COORDINATE is a table and not a view? Normally a simple query like this should not require any temp space. As someone already mentioned in this thread, get an explain for the query. Once you do, post it here, maybe someone will be able to help you then.
Regards, Miro
Jean-Marc,
Do you mean: SET CURRENT QUERY OPTIMIZATION 1? The current value is 7 at the mo.
Thanks,
Bing
Jean-Marc Blaise wrote: Bing, is the access plan with a default query set to 1 the same - relation scan and not index scan ?
Jean-Marc
"Bing Wu" <bi**@biop.ox.ac.uk> a ?rit dans le message de news:bq**********@news.ox.ac.uk...
Yes, it's a table with over a billion rows. I have run the SQL explain and
please find the result below.
Thanks again,
Bing
Package Name = "DB2ADMIN"."DYNEXPLN" Version = ""
Prep Date = 2003/12/04 Prep Time = 15:36:33
Bind Timestamp = 2003-12-04-15.36.33.960521
Isolation Level = Cursor Stability Blocking = Block Unambiguous Cursors Query Optimization Class = 7
Partition Parallel = No Intra-Partition Parallel = Yes (Bind Degree = ANY)
SQL Path = "SYSIBM", "SYSFUN", "SYSPROC",
"DB2ADMIN"
-------------------- SECTION --------------------------------------- Section = 1
SQL Statement: DECLARE C1 CURSOR FOR SELECT COUNT(*) FROM COORDINATE
Intra-Partition Parallelism Degree = 2
Section Code Page = 819
Estimated Cost = 8889258.000000 Estimated Cardinality = 1.000000
Process Using 2 Subagents | Access Table Name = DB2ADMIN.COORDINATE ID = 4,4 | | #Columns = 0 | | Parallel Scan | | Relation Scan | | | Prefetch: Eligible | | Lock Intents | | | Table: Intent Share | | | Row : Next Key Share | | Sargable Predicate(s) | | | Partial Predicate Aggregation | | | | Column Function(s) | Partial Aggregation Completion | | Column Function(s) | Insert Into Asynchronous Local Table Queue ID = q1 Access Local Table Queue ID = q1 #Columns = 1 Final Aggregation | Column Function(s) Return Data to Application | #Columns = 1
End of section
miro flasza wrote:
Are you certain that COORDINATE is a table and not a view? Normally a simple query like this should not require any temp space. As someone already mentioned in this thread, get an explain for the query. Once you do, post it here, maybe someone will be able to help you then.
Regards, Miro
No, I'm speaking about SET CURRENT DEGREE = '1' , to inhibate the intra
parallelism and see what's the explain gives. You can either set the
max_querydegree parameter in the DB CFG to 1 and change it back, online.
Cheers,
Jean-Marc
"Bing Wu" <bi**@biop.ox.ac.uk> a écrit dans le message de
news:bq**********@news.ox.ac.uk... Jean-Marc,
Do you mean: SET CURRENT QUERY OPTIMIZATION 1? The current value is 7 at
the mo. Thanks,
Bing
Jean-Marc Blaise wrote: Bing, is the access plan with a default query set to 1 the same -
relation scan and not index scan ?
Jean-Marc
"Bing Wu" <bi**@biop.ox.ac.uk> a ?rit dans le message de news:bq**********@news.ox.ac.uk...
Yes, it's a table with over a billion rows. I have run the SQL explain
and please find the result below.
Thanks again,
Bing
Package Name = "DB2ADMIN"."DYNEXPLN" Version = ""
Prep Date = 2003/12/04 Prep Time = 15:36:33
Bind Timestamp = 2003-12-04-15.36.33.960521
Isolation Level = Cursor Stability Blocking = Block Unambiguous Cursors Query Optimization Class = 7
Partition Parallel = No Intra-Partition Parallel = Yes (Bind Degree = ANY)
SQL Path = "SYSIBM", "SYSFUN", "SYSPROC",
"DB2ADMIN"
-------------------- SECTION --------------------------------------- Section = 1
SQL Statement: DECLARE C1 CURSOR FOR SELECT COUNT(*) FROM COORDINATE
Intra-Partition Parallelism Degree = 2
Section Code Page = 819
Estimated Cost = 8889258.000000 Estimated Cardinality = 1.000000
Process Using 2 Subagents | Access Table Name = DB2ADMIN.COORDINATE ID = 4,4 | | #Columns = 0 | | Parallel Scan | | Relation Scan | | | Prefetch: Eligible | | Lock Intents | | | Table: Intent Share | | | Row : Next Key Share | | Sargable Predicate(s) | | | Partial Predicate Aggregation | | | | Column Function(s) | Partial Aggregation Completion | | Column Function(s) | Insert Into Asynchronous Local Table Queue ID = q1 Access Local Table Queue ID = q1 #Columns = 1 Final Aggregation | Column Function(s) Return Data to Application | #Columns = 1
End of section
miro flasza wrote:
Are you certain that COORDINATE is a table and not a view? Normally a simple query like this should not require any temp space. As someone already mentioned in this thread, get an explain for the query. Once you do, post it here, maybe someone will be able to help you then.
Regards, Miro
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