RE: Help Needed regarding performance improvement of delete query
And replying to Scott's post to say thanks for the compliment, but I've just had another idea ... How many fields are you using for your select on the master file? ESPECIALLY if it's just the date, trans that across to your secondary file, and index it! If it's more than one field, try and work out a usable trans that will pull all the fields across in one index that you can run a select over. Don't forget, declaring an index means that that data is stored in the file, whether it was calculated, trans'd, or was in the file anyway. So now you can do a select and purge on your secondary file without ever having to go near the primary, and the database will take care of making sure all the required information is available as it's needed ... :-) Cheers, Wol -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Scott Richardson Sent: 15 March 2004 13:08 To: U2 Users Discussion List Subject: Re: Help Needed regarding performance improvement of delete query Great points from Wol, as always. What kind of /tmp disk space do you have on this system? (Assuming that /tmp is where UV does some of it's SELECT scratch pad intermediate writing when processing large queries, consult your sites actual uvconfig for all of your actual values...). If this /tmp is small, single physical disk, or heavily fragmented, this would also contribute to poor query runtime performance. Ditto on your system's swap space, which should be at least 2X physical memory. Wol's approach of breaking down the query into selecting smaller groups of data is a great one. Chip away at the stone, methodically, consistently, and constantly. What platform is this on? What OS version? What UV Version? How much memory disk space? How much /tmp and swap space? Are you running this query with other users on the system, who may be also trying to access the files this query is working with? Are you runing this at night when it might conflict with a backup operation? More food for thought. Regards, Scott - Original Message - From: Anthony Youngman [EMAIL PROTECTED] To: U2 Users Discussion List [EMAIL PROTECTED] Sent: Monday, March 15, 2004 4:02 AM Subject: RE: Help Needed regarding performance improvement of delete query This might help speed things up a bit ... Firstly, of course, is your file properly sized? Secondly, (and in this case you will need to run the SELECT / DELETE sequence several times) try putting a SAMPLE 1000 (or whatever number makes sense) at the end of your select. Basically, this will mean that the SELECT runs until it finds that number of records and then stops. So each sequence won't load the system so badly. Creating a huge select list will stress your ram badly ... looping through this sequence won't stress the system so badly, though you really do need to use indices to reduce the stress even more ... Create an index on various fields that you're using as your select criteria. If you're selecting old records, then you need to select on date, and this really will make life both easy and fast. The more closely you can guarantee that a select, acting on a single index, will pick up only or mostly records that you are going to delete, the better. That will SERIOUSLY reduce the time taken and the performance hit. Cheers, Wol -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of ashish ratna Sent: 15 March 2004 08:25 To: [EMAIL PROTECTED] Subject: Help Needed regarding performance improvement of delete query Hi All, We are working for purging of old data from the database. But we are facing performance problems in this. We are using select query which is created dynamically on the basis of number of records. We want to know if there is any limit for size of query in Universe. Although in universe help pdf it is mentioned that there is no limit for the length of select query. But when we run the program on the file with records more than 0.5 million it gave the error- Pid 14433 received a SIGSEGV for stack growth failure. Possible causes: insufficient memory or swap space, or stack size exceeded maxssiz. Memory fault(coredump) If there is no limitation on the size of query then please suggest some other possible solution which can help us reducing the time of query and completing the process successfully without giving the error. Thanks in advance. Regards, Ashish. *** This transmission is intended for the named recipient only. It may contain private and confidential information. If this has come to you in error you must not act on anything disclosed in it, nor must you copy it, modify it, disseminate it in any way, or show it to anyone. Please e-mail the sender to inform us of the transmission error or telephone ECA International immediately and delete the e-mail from your information system. Telephone numbers for ECA International
Re: Help Needed regarding performance improvement of delete query
In a message dated 3/15/2004 9:54:01 AM Eastern Standard Time, [EMAIL PROTECTED] writes: 10 READNEXT ID ELSE STOP READV DTE FROM F.MASTER, ID, 5 ELSE GOTO 10 IF DTE GT DEL.DATE THEN GOTO 10 DELETE F.MASTER, ID DELETE F.REFERENCE, ID GOTO 10 I count three goto's So three times through the spank machine. Will -- u2-users mailing list [EMAIL PROTECTED] http://www.oliver.com/mailman/listinfo/u2-users
Re: Help Needed regarding performance improvement of delete query
Gives Mark the most improved player award. Will In a message dated 3/16/2004 5:07:09 PM Eastern Standard Time, [EMAIL PROTECTED] writes: LOOP WHILE READNEXT ID DO READV DTE FROM F.MASTER, ID, 5 THEN IF DTE LE DEL.DATE THEN DELETE F.MASTER, ID DELETE F.REFERENCE, ID END END REPEAT there you go (to). -- u2-users mailing list [EMAIL PROTECTED] http://www.oliver.com/mailman/listinfo/u2-users
RE: Help Needed regarding performance improvement of delete query
I personally like this approach... LOOP READNEXT ID ELSE EXIT READV DTE FROM F.MASTER, ID, 5 ELSE CONTINUE IF DTE LE DEL.DATE ELSE CONTINUE DELETE F.MASTER, ID DELETE F.REFERENCE, ID REPEAT That's my $0.02 worth. (If that!) Grant -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Tuesday, March 16, 2004 6:08 PM To: U2 Users Discussion List Subject: Re: Help Needed regarding performance improvement of delete query Gives Mark the most improved player award. Will In a message dated 3/16/2004 5:07:09 PM Eastern Standard Time, [EMAIL PROTECTED] writes: LOOP WHILE READNEXT ID DO READV DTE FROM F.MASTER, ID, 5 THEN IF DTE LE DEL.DATE THEN DELETE F.MASTER, ID DELETE F.REFERENCE, ID END END REPEAT there you go (to). -- u2-users mailing list [EMAIL PROTECTED] http://www.oliver.com/mailman/listinfo/u2-users -- u2-users mailing list [EMAIL PROTECTED] http://www.oliver.com/mailman/listinfo/u2-users
RE: Help Needed regarding performance improvement of delete query
Hi Wol, The scenario is that- We have a master file having more than 3-4 million records and have corresponding reference file which contains reference data for this master file. Now we start our purge program which selects records from master file on the basis of date. Corresponding data should be deleted from the other file (reference file). For this requirement we have adopted the approach that- select the record from master file on the basis of date. Save the list of these records, then on the basis of this list select the records from reference file. Issue is that this list contains more than 0.5 million and I want to take few (say 10,000 at a time) record ids from this list for further processing. Any pointers for this problem will be very helpful. Thanks in advance. Ashish. -Original Message- From: Anthony Youngman [mailto:[EMAIL PROTECTED] Sent: Monday, March 15, 2004 4:50 PM To: ashish ratna Subject: RE: Help Needed regarding performance improvement of delete query Ahhh I thought you were selecting records and deleting them. So the first thousand would have disappeared, and you would obviously get a different thousand next time round because the first lot would have gone :-) Sounds like that's not the case. In that case, do you have a field that is repeated across many records, but where each individual value (or range of values) wouldn't return too big a bunch of records? Or do you have a numeric id - you could declare an index on that ... Let's take that numeric id idea - and then you'll have to build on it for yourself. Declare an i-descriptor as @ID[3]. That logically partitions your file into a thousand pieces. Declare an index on this. The first term in your select will then be WITH IDESC EQ whatever-number-you-want. That'll reduce the load on the database for each pass, you'll just need to wrap it in a loop where whatever-number goes from 0 to 999 Actually, what I would probably do is declare my i-descriptor as INT(@ID/30) and then run this purge daily with whatever-number as today's day. Obviously, it'll do nothing on the 31sts, and in March it'll do two month's work on the 29th and 30th, but you've reduced the hit on the system considerably. Without knowing what you're doing in more detail, it's difficult to give you any proper advice, but certainly I'll try and think of any tips that you can build upon, like this. But you need to work out what's right for you :-) NB Any reason for taking this off the mailing list? By all means cc it to me, but if you keep it on the list there are other people who may be able to help too - I'm very good at overviews, but I fall short on the logic - I think there is a way to get the next thousand records, but I haven't got a clue what the syntax is ... Cheers, Wol -Original Message- From: ashish ratna [mailto:[EMAIL PROTECTED] Sent: 15 March 2004 10:33 To: Anthony Youngman Subject: RE: Help Needed regarding performance improvement of delete query Hi, Thanks for the nice suggestions. I have another question that, using SAMPLE once I process 1000 records (using SAMPLE 1000), how can I select next 1000 records in next run (i.e. 1001 to 2000 records and so on)? I was trying few combinations but didn't succeeded. Can you tell me the syntax for that? Thanks again. Regards, Ashish. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Anthony Youngman Sent: Monday, March 15, 2004 2:32 PM To: U2 Users Discussion List Subject: RE: Help Needed regarding performance improvement of delete query This might help speed things up a bit ... Firstly, of course, is your file properly sized? Secondly, (and in this case you will need to run the SELECT / DELETE sequence several times) try putting a SAMPLE 1000 (or whatever number makes sense) at the end of your select. Basically, this will mean that the SELECT runs until it finds that number of records and then stops. So each sequence won't load the system so badly. Creating a huge select list will stress your ram badly ... looping through this sequence won't stress the system so badly, though you really do need to use indices to reduce the stress even more ... Create an index on various fields that you're using as your select criteria. If you're selecting old records, then you need to select on date, and this really will make life both easy and fast. The more closely you can guarantee that a select, acting on a single index, will pick up only or mostly records that you are going to delete, the better. That will SERIOUSLY reduce the time taken and the performance hit. Cheers, Wol -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of ashish ratna Sent: 15 March 2004 08:25 To: [EMAIL PROTECTED] Subject: Help Needed regarding performance improvement of delete query Hi All, We are working for purging of old data from the database. But we are facing performance problems in this. We are using select
Re: Help Needed regarding performance improvement of delete query
Great points from Wol, as always. What kind of /tmp disk space do you have on this system? (Assuming that /tmp is where UV does some of it's SELECT scratch pad intermediate writing when processing large queries, consult your sites actual uvconfig for all of your actual values...). If this /tmp is small, single physical disk, or heavily fragmented, this would also contribute to poor query runtime performance. Ditto on your system's swap space, which should be at least 2X physical memory. Wol's approach of breaking down the query into selecting smaller groups of data is a great one. Chip away at the stone, methodically, consistently, and constantly. What platform is this on? What OS version? What UV Version? How much memory disk space? How much /tmp and swap space? Are you running this query with other users on the system, who may be also trying to access the files this query is working with? Are you runing this at night when it might conflict with a backup operation? More food for thought. Regards, Scott - Original Message - From: Anthony Youngman [EMAIL PROTECTED] To: U2 Users Discussion List [EMAIL PROTECTED] Sent: Monday, March 15, 2004 4:02 AM Subject: RE: Help Needed regarding performance improvement of delete query This might help speed things up a bit ... Firstly, of course, is your file properly sized? Secondly, (and in this case you will need to run the SELECT / DELETE sequence several times) try putting a SAMPLE 1000 (or whatever number makes sense) at the end of your select. Basically, this will mean that the SELECT runs until it finds that number of records and then stops. So each sequence won't load the system so badly. Creating a huge select list will stress your ram badly ... looping through this sequence won't stress the system so badly, though you really do need to use indices to reduce the stress even more ... Create an index on various fields that you're using as your select criteria. If you're selecting old records, then you need to select on date, and this really will make life both easy and fast. The more closely you can guarantee that a select, acting on a single index, will pick up only or mostly records that you are going to delete, the better. That will SERIOUSLY reduce the time taken and the performance hit. Cheers, Wol -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of ashish ratna Sent: 15 March 2004 08:25 To: [EMAIL PROTECTED] Subject: Help Needed regarding performance improvement of delete query Hi All, We are working for purging of old data from the database. But we are facing performance problems in this. We are using select query which is created dynamically on the basis of number of records. We want to know if there is any limit for size of query in Universe. Although in universe help pdf it is mentioned that there is no limit for the length of select query. But when we run the program on the file with records more than 0.5 million it gave the error- Pid 14433 received a SIGSEGV for stack growth failure. Possible causes: insufficient memory or swap space, or stack size exceeded maxssiz. Memory fault(coredump) If there is no limitation on the size of query then please suggest some other possible solution which can help us reducing the time of query and completing the process successfully without giving the error. Thanks in advance. Regards, Ashish. *** This transmission is intended for the named recipient only. It may contain private and confidential information. If this has come to you in error you must not act on anything disclosed in it, nor must you copy it, modify it, disseminate it in any way, or show it to anyone. Please e-mail the sender to inform us of the transmission error or telephone ECA International immediately and delete the e-mail from your information system. Telephone numbers for ECA International offices are: Sydney +61 (0)2 9911 7799, Hong Kong + 852 2121 2388, London +44 (0)20 7351 5000 and New York +1 212 582 2333. *** -- u2-users mailing list [EMAIL PROTECTED] http://www.oliver.com/mailman/listinfo/u2-users -- u2-users mailing list [EMAIL PROTECTED] http://www.oliver.com/mailman/listinfo/u2-users
Re: Help Needed regarding performance improvement of delete query
Folks, It's a real nightmare when you have to purge +2gig files, eh? They can run for weeks and have your users complaining that entire week too. Nag.. nag..nag... Simple solution: Backup entire data file to media. Select what you want to KEEP and move those records to a temp file. Clearfile in a basic program or delete old data file. Rename temp file or copy records back to original data file. If you have a exclusive access window, this is a piece of cake; otherwise, you have to become more creative and carve out your own customized exclusive access window on the fly and use a whole host of mirrors hoping the phone doesn't ring with your fingerprints all over a potiential mess --- just in case you get distracted and mis-shuffle the deck :p) Bram - Original Message - From: ashish ratna To: Anthony Youngman Cc: [EMAIL PROTECTED] Sent: Monday, March 15, 2004 7:55 AM Subject: RE: Help Needed regarding performance improvement of delete query Hi Wol, The scenario is that- We have a master file having more than 3-4 million records and have corresponding reference file which contains reference data for this master file. Now we start our purge program which selects records from master file on the basis of date. Corresponding data should be deleted from the other file (reference file). For this requirement we have adopted the approach that- select the record from master file on the basis of date. Save the list of these records, then on the basis of this list select the records from reference file. Issue is that this list contains more than 0.5 million and I want to take few (say 10,000 at a time) record ids from this list for further processing. Any pointers for this problem will be very helpful. Thanks in advance. Ashish. -Original Message- From: Anthony Youngman [mailto:[EMAIL PROTECTED] Sent: Monday, March 15, 2004 4:50 PM To: ashish ratna Subject: RE: Help Needed regarding performance improvement of delete query Ahhh I thought you were selecting records and deleting them. So the first thousand would have disappeared, and you would obviously get a different thousand next time round because the first lot would have gone :-) Sounds like that's not the case. In that case, do you have a field that is repeated across many records, but where each individual value (or range of values) wouldn't return too big a bunch of records? Or do you have a numeric id - you could declare an index on that ... Let's take that numeric id idea - and then you'll have to build on it for yourself. Declare an i-descriptor as @ID[3]. That logically partitions your file into a thousand pieces. Declare an index on this. The first term in your select will then be WITH IDESC EQ whatever-number-you-want. That'll reduce the load on the database for each pass, you'll just need to wrap it in a loop where whatever-number goes from 0 to 999 Actually, what I would probably do is declare my i-descriptor as INT(@ID/30) and then run this purge daily with whatever-number as today's day. Obviously, it'll do nothing on the 31sts, and in March it'll do two month's work on the 29th and 30th, but you've reduced the hit on the system considerably. Without knowing what you're doing in more detail, it's difficult to give you any proper advice, but certainly I'll try and think of any tips that you can build upon, like this. But you need to work out what's right for you :-) NB Any reason for taking this off the mailing list? By all means cc it to me, but if you keep it on the list there are other people who may be able to help too - I'm very good at overviews, but I fall short on the logic - I think there is a way to get the next thousand records, but I haven't got a clue what the syntax is ... Cheers, Wol -Original Message- From: ashish ratna [mailto:[EMAIL PROTECTED] Sent: 15 March 2004 10:33 To: Anthony Youngman Subject: RE: Help Needed regarding performance improvement of delete query Hi, Thanks for the nice suggestions. I have another question that, using SAMPLE once I process 1000 records (using SAMPLE 1000), how can I select next 1000 records in next run (i.e. 1001 to 2000 records and so on)? I was trying few combinations but didn't succeeded. Can you tell me the syntax for that? Thanks again. Regards, Ashish. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Anthony Youngman Sent: Monday, March 15, 2004 2:32 PM To: U2 Users Discussion List Subject: RE: Help Needed regarding performance improvement of delete query This might help speed things up a bit ... Firstly, of course, is your file properly sized? Secondly, (and in this case you will need to run the SELECT / DELETE sequence several times) try putting a SAMPLE 1000 (or whatever number makes sense) at the end of your select
Re: Help Needed regarding performance improvement of delete query
Oh, by the way Don't forget to use fuser in unix or the equalivant on Bill Gates' machines in order to verify that you truly do have exclusive access rights; otherwise, no worky. - Original Message - From: Mike Masters To: U2 Users Discussion List Sent: Monday, March 15, 2004 8:24 AM Subject: Re: Help Needed regarding performance improvement of delete query I forgot to mention why. U2 definately prefers ADDing records instead of DELETing records.. any day. - Original Message - From: ashish ratna To: Anthony Youngman Cc: [EMAIL PROTECTED] Sent: Monday, March 15, 2004 7:55 AM Subject: RE: Help Needed regarding performance improvement of delete query Hi Wol, The scenario is that- We have a master file having more than 3-4 million records and have corresponding reference file which contains reference data for this master file. Now we start our purge program which selects records from master file on the basis of date. Corresponding data should be deleted from the other file (reference file). For this requirement we have adopted the approach that- select the record from master file on the basis of date. Save the list of these records, then on the basis of this list select the records from reference file. Issue is that this list contains more than 0.5 million and I want to take few (say 10,000 at a time) record ids from this list for further processing. Any pointers for this problem will be very helpful. Thanks in advance. Ashish. -Original Message- From: Anthony Youngman [mailto:[EMAIL PROTECTED] Sent: Monday, March 15, 2004 4:50 PM To: ashish ratna Subject: RE: Help Needed regarding performance improvement of delete query Ahhh I thought you were selecting records and deleting them. So the first thousand would have disappeared, and you would obviously get a different thousand next time round because the first lot would have gone :-) Sounds like that's not the case. In that case, do you have a field that is repeated across many records, but where each individual value (or range of values) wouldn't return too big a bunch of records? Or do you have a numeric id - you could declare an index on that ... Let's take that numeric id idea - and then you'll have to build on it for yourself. Declare an i-descriptor as @ID[3]. That logically partitions your file into a thousand pieces. Declare an index on this. The first term in your select will then be WITH IDESC EQ whatever-number-you-want. That'll reduce the load on the database for each pass, you'll just need to wrap it in a loop where whatever-number goes from 0 to 999 Actually, what I would probably do is declare my i-descriptor as INT(@ID/30) and then run this purge daily with whatever-number as today's day. Obviously, it'll do nothing on the 31sts, and in March it'll do two month's work on the 29th and 30th, but you've reduced the hit on the system considerably. Without knowing what you're doing in more detail, it's difficult to give you any proper advice, but certainly I'll try and think of any tips that you can build upon, like this. But you need to work out what's right for you :-) NB Any reason for taking this off the mailing list? By all means cc it to me, but if you keep it on the list there are other people who may be able to help too - I'm very good at overviews, but I fall short on the logic - I think there is a way to get the next thousand records, but I haven't got a clue what the syntax is ... Cheers, Wol -Original Message- From: ashish ratna [mailto:[EMAIL PROTECTED] Sent: 15 March 2004 10:33 To: Anthony Youngman Subject: RE: Help Needed regarding performance improvement of delete query Hi, Thanks for the nice suggestions. I have another question that, using SAMPLE once I process 1000 records (using SAMPLE 1000), how can I select next 1000 records in next run (i.e. 1001 to 2000 records and so on)? I was trying few combinations but didn't succeeded. Can you tell me the syntax for that? Thanks again. Regards, Ashish. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Anthony Youngman Sent: Monday, March 15, 2004 2:32 PM To: U2 Users Discussion List Subject: RE: Help Needed regarding performance improvement of delete query This might help speed things up a bit ... Firstly, of course, is your file properly sized? Secondly, (and in this case you will need to run the SELECT / DELETE sequence several times) try putting a SAMPLE 1000 (or whatever number makes sense) at the end of your select. Basically, this will mean that the SELECT runs until it finds that number of records and then stops
Re: Help Needed regarding performance improvement of delete query
I have a client that needs roughly 250,000 items removed monthly from a file containing 5-6 million records. Since there is no need to use the keys (records) for any other purpose except for deleting because they are old, a standard data/basic SELECT statement is just about as fast as you can get. It isn't encumbered by the number of selected keys as it's not retaining them for any purpose. This simple program looks like this: OPEN MASTER TO F.MASTER ELSE STOP OPEN REFERENCE TO F.REFERENCE ELSE STOP DEL.DTE=ICONV(01/02/2003,D) SELECT F.MASTER 10 READNEXT ID ELSE STOP READV DTE FROM F.MASTER, ID, 5 ELSE GOTO 10 IF DTE GT DEL.DATE THEN GOTO 10 DELETE F.MASTER, ID DELETE F.REFERENCE, ID GOTO 10 END Of course if there's additional use for the deleted keys, then use another approach. my 1 cent. - Original Message - From: ashish ratna [EMAIL PROTECTED] To: Anthony Youngman [EMAIL PROTECTED] Cc: [EMAIL PROTECTED] Sent: Monday, March 15, 2004 7:55 AM Subject: RE: Help Needed regarding performance improvement of delete query Hi Wol, The scenario is that- We have a master file having more than 3-4 million records and have corresponding reference file which contains reference data for this master file. Now we start our purge program which selects records from master file on the basis of date. Corresponding data should be deleted from the other file (reference file). For this requirement we have adopted the approach that- select the record from master file on the basis of date. Save the list of these records, then on the basis of this list select the records from reference file. Issue is that this list contains more than 0.5 million and I want to take few (say 10,000 at a time) record ids from this list for further processing. Any pointers for this problem will be very helpful. Thanks in advance. Ashish. -Original Message- From: Anthony Youngman [mailto:[EMAIL PROTECTED] Sent: Monday, March 15, 2004 4:50 PM To: ashish ratna Subject: RE: Help Needed regarding performance improvement of delete query Ahhh I thought you were selecting records and deleting them. So the first thousand would have disappeared, and you would obviously get a different thousand next time round because the first lot would have gone :-) Sounds like that's not the case. In that case, do you have a field that is repeated across many records, but where each individual value (or range of values) wouldn't return too big a bunch of records? Or do you have a numeric id - you could declare an index on that ... Let's take that numeric id idea - and then you'll have to build on it for yourself. Declare an i-descriptor as @ID[3]. That logically partitions your file into a thousand pieces. Declare an index on this. The first term in your select will then be WITH IDESC EQ whatever-number-you-want. That'll reduce the load on the database for each pass, you'll just need to wrap it in a loop where whatever-number goes from 0 to 999 Actually, what I would probably do is declare my i-descriptor as INT(@ID/30) and then run this purge daily with whatever-number as today's day. Obviously, it'll do nothing on the 31sts, and in March it'll do two month's work on the 29th and 30th, but you've reduced the hit on the system considerably. Without knowing what you're doing in more detail, it's difficult to give you any proper advice, but certainly I'll try and think of any tips that you can build upon, like this. But you need to work out what's right for you :-) NB Any reason for taking this off the mailing list? By all means cc it to me, but if you keep it on the list there are other people who may be able to help too - I'm very good at overviews, but I fall short on the logic - I think there is a way to get the next thousand records, but I haven't got a clue what the syntax is ... Cheers, Wol -Original Message- From: ashish ratna [mailto:[EMAIL PROTECTED] Sent: 15 March 2004 10:33 To: Anthony Youngman Subject: RE: Help Needed regarding performance improvement of delete query Hi, Thanks for the nice suggestions. I have another question that, using SAMPLE once I process 1000 records (using SAMPLE 1000), how can I select next 1000 records in next run (i.e. 1001 to 2000 records and so on)? I was trying few combinations but didn't succeeded. Can you tell me the syntax for that? Thanks again. Regards, Ashish. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Anthony Youngman Sent: Monday, March 15, 2004 2:32 PM To: U2 Users Discussion List Subject: RE: Help Needed regarding performance improvement of delete query This might help speed things up a bit ... Firstly, of course, is your file properly sized? Secondly, (and in this case you will need to run the SELECT / DELETE sequence several times) try putting a SAMPLE 1000 (or whatever number makes sense) at the end of your select. Basically, this will mean that the SELECT runs until it finds
