RE: [sqlite] Very Slow delete times on larger databases, please help!
Yes we found this out too. We never vacuum the file, it is acceptable for it to just get larger not smaller. We generate an indication on the current database capacity not from the file size but from the total number of pages in the database file minus the number of free pages in the database. So these times are not affected by vacuum. Thanks Mark > -Original Message- > From: Brett Wilson [mailto:[EMAIL PROTECTED] > Sent: 26 October 2005 19:22 > To: sqlite-users@sqlite.org > Subject: Re: [sqlite] Very Slow delete times on larger > databases, please > help! > > > Vacuuming is just slow. I don't think there is much you can do except > don't do it unless you really need it, and don't turn on autovacuum. > > Brett > > On 10/26/05, R S <[EMAIL PROTECTED]> wrote: > > In my case Delete happens reasonably OK but Vaccuuming > takes incredibly > > long? > > > > > > On 10/21/05, Allan, Mark <[EMAIL PROTECTED]> wrote: > > > > > > > > > Thanks to both Christian Smith and John Stanton for your posts. > > > > > > > On Wed, 19 Oct 2005, Christian Smith wrote: > > > > From the VDBE output you originally posted, you are doing a > > > > fair amount of > > > > work for each deleted row: > > > > - Index search to find the next row from EXAMINATIONS to delete > > > > - Removing the row from 3 indexes on EXAMINATIONS > > > > - (trigger) Remove related row in SPIRO_TEST from 2 indexes > > > > on SPIRO_TEST > > > > - (trigger) Remove related row in SPIRO_TEST > > > > - Remove the row from EXAMINATIONS > > > > > > > > Check your cache size. If the above work is causing the > 75 page entry > > > > cache to thrash, you're likely to hit worst case > performance as the > > > > thrashing pages may be being accessed in a cyclical fashion. > > > > Not sure how > > > > like it is that your page cache is not big enough. How > big is a row of > > > > data, typically? > > > > > > Our cache size is 75 pages of 8192 bytes = 600Kb. > > > > > > The maximum size of an EXAMINATIONS record is about 500 > bytes, 450 bytes > > > of this is a varchar field. In the test example the > average size of an > > > EXAMINATIONS record is 60 bytes as not much text is saved. > > > > > > The maximum size of a SPIRO_TEST record is about 5Kb, > these will vary from > > > test to test, but for the test example the size of each > SPIRO_TEST record is > > > fixed to approx 1Kb. > > > > > > Based on this I dont think that we should be thrashing > the cache. I am > > > however unsure how SQlite works here. > > > > > > > Also, a 60x slowdown is not to be unexpected. The PC > version, while > > > > probably having the same SQLite page cache size in the SQLite > > > > app itself, > > > > will most likely be reading and writing to the OSes > cache at memory to > > > > memory copy speed most of the time, with synchronous writes > > > > only done when > > > > needed. The embedded platform you're using probably > writes straight to > > > > FLASH, which is necassarily a synchronous operation if > your OS doesn't > > > > have a cache between your app and the FLASH FS. While flash > > > > writes are low > > > > latency, they are also low bandwidth, and won't be > within an order of > > > > magnitude of performance when compared to a desktop PC > write to OS > > > > filesystem cache. > > > > > > > > Finally, you give no indication on the actual CPU speed of > > > > the embedded > > > > platform. It's quite reasonable to assume a development > PC could be an > > > > order of magnitude faster on sheer integer throughput. I'm > > > > amazed how slow > > > > my 50MHz microSPARC based SPARCclassic is. Such a platform > > > > would not be > > > > much, if at all, slower than a modern embedded > platform, and has the > > > > benefit of gobs of RAM, but still runs the same code > two orders of > > > > magnitude slower at least than my Athlon XP 1700 based > > > > desktop. You have > > > > to keep your performance expectations realistic. You > are, afterall, > > > > running a complete, ACID transaction, SQL relational database. > > > > > > > > > The maximum CPU speed of our ARM7 chip is 71Mhz. > >
Re: [sqlite] Very Slow delete times on larger databases, please help!
Vacuuming is just slow. I don't think there is much you can do except don't do it unless you really need it, and don't turn on autovacuum. Brett On 10/26/05, R S <[EMAIL PROTECTED]> wrote: > In my case Delete happens reasonably OK but Vaccuuming takes incredibly > long? > > > On 10/21/05, Allan, Mark <[EMAIL PROTECTED]> wrote: > > > > > > Thanks to both Christian Smith and John Stanton for your posts. > > > > > On Wed, 19 Oct 2005, Christian Smith wrote: > > > From the VDBE output you originally posted, you are doing a > > > fair amount of > > > work for each deleted row: > > > - Index search to find the next row from EXAMINATIONS to delete > > > - Removing the row from 3 indexes on EXAMINATIONS > > > - (trigger) Remove related row in SPIRO_TEST from 2 indexes > > > on SPIRO_TEST > > > - (trigger) Remove related row in SPIRO_TEST > > > - Remove the row from EXAMINATIONS > > > > > > Check your cache size. If the above work is causing the 75 page entry > > > cache to thrash, you're likely to hit worst case performance as the > > > thrashing pages may be being accessed in a cyclical fashion. > > > Not sure how > > > like it is that your page cache is not big enough. How big is a row of > > > data, typically? > > > > Our cache size is 75 pages of 8192 bytes = 600Kb. > > > > The maximum size of an EXAMINATIONS record is about 500 bytes, 450 bytes > > of this is a varchar field. In the test example the average size of an > > EXAMINATIONS record is 60 bytes as not much text is saved. > > > > The maximum size of a SPIRO_TEST record is about 5Kb, these will vary from > > test to test, but for the test example the size of each SPIRO_TEST record is > > fixed to approx 1Kb. > > > > Based on this I dont think that we should be thrashing the cache. I am > > however unsure how SQlite works here. > > > > > Also, a 60x slowdown is not to be unexpected. The PC version, while > > > probably having the same SQLite page cache size in the SQLite > > > app itself, > > > will most likely be reading and writing to the OSes cache at memory to > > > memory copy speed most of the time, with synchronous writes > > > only done when > > > needed. The embedded platform you're using probably writes straight to > > > FLASH, which is necassarily a synchronous operation if your OS doesn't > > > have a cache between your app and the FLASH FS. While flash > > > writes are low > > > latency, they are also low bandwidth, and won't be within an order of > > > magnitude of performance when compared to a desktop PC write to OS > > > filesystem cache. > > > > > > Finally, you give no indication on the actual CPU speed of > > > the embedded > > > platform. It's quite reasonable to assume a development PC could be an > > > order of magnitude faster on sheer integer throughput. I'm > > > amazed how slow > > > my 50MHz microSPARC based SPARCclassic is. Such a platform > > > would not be > > > much, if at all, slower than a modern embedded platform, and has the > > > benefit of gobs of RAM, but still runs the same code two orders of > > > magnitude slower at least than my Athlon XP 1700 based > > > desktop. You have > > > to keep your performance expectations realistic. You are, afterall, > > > running a complete, ACID transaction, SQL relational database. > > > > > > The maximum CPU speed of our ARM7 chip is 71Mhz. > > > > > Others have indicated that dropping indexes might help when > > > deleting or > > > inserting records. However, have you tried simply not having > > > indexes at > > > all? Would that cause unacceptable slowdown? Perhaps, for the > > > demo query > > > from the original post, just keep the DATE index on > > > EXAMINATIONS, and use > > > full table scans for queries based on EXAM_TYPE and > > > STATUS_FLAG. Truth is, > > > given the small number of EXAM_TYPE and STATUS_FLAG values (I > > > presume), > > > you're as well just doing table scans when looking for > > > specific exam types > > > and statuses. Indexes only really help when you have a large > > > variation in > > > values with few collisions. Doing this will leave a single > > > index update in > > > addition to the actual row removals, which should improve performance. > > > > I have tried permanently dropping the indexes on EXAM_TYPE and STATUS_FLAG > > and this gives some improvement in time. Indeed it does seem that the > > STATUS_FLAG index is worthless and in the initial version of the software we > > will have only 1 EXAM_TYPE (although this will increase for each module we > > release over the next few months). > > > > I have also tried the suggested method of dropping the > > EXAM_PATIENT_ID_INDEX index on the examinations table before delete and > > rebuilding it on completion. I cannot delete the remaining indexes as they > > are used during the delete operation and this slows the whole operation > > down. > > > > The latest changes have reduced the time to delete the same number of > > records from 3:45 minutes to 2:53 minutes. Still a long time to wait but
Re: [sqlite] Very Slow delete times on larger databases, please help!
In my case Delete happens reasonably OK but Vaccuuming takes incredibly long? On 10/21/05, Allan, Mark <[EMAIL PROTECTED]> wrote: > > > Thanks to both Christian Smith and John Stanton for your posts. > > > On Wed, 19 Oct 2005, Christian Smith wrote: > > From the VDBE output you originally posted, you are doing a > > fair amount of > > work for each deleted row: > > - Index search to find the next row from EXAMINATIONS to delete > > - Removing the row from 3 indexes on EXAMINATIONS > > - (trigger) Remove related row in SPIRO_TEST from 2 indexes > > on SPIRO_TEST > > - (trigger) Remove related row in SPIRO_TEST > > - Remove the row from EXAMINATIONS > > > > Check your cache size. If the above work is causing the 75 page entry > > cache to thrash, you're likely to hit worst case performance as the > > thrashing pages may be being accessed in a cyclical fashion. > > Not sure how > > like it is that your page cache is not big enough. How big is a row of > > data, typically? > > Our cache size is 75 pages of 8192 bytes = 600Kb. > > The maximum size of an EXAMINATIONS record is about 500 bytes, 450 bytes > of this is a varchar field. In the test example the average size of an > EXAMINATIONS record is 60 bytes as not much text is saved. > > The maximum size of a SPIRO_TEST record is about 5Kb, these will vary from > test to test, but for the test example the size of each SPIRO_TEST record is > fixed to approx 1Kb. > > Based on this I dont think that we should be thrashing the cache. I am > however unsure how SQlite works here. > > > Also, a 60x slowdown is not to be unexpected. The PC version, while > > probably having the same SQLite page cache size in the SQLite > > app itself, > > will most likely be reading and writing to the OSes cache at memory to > > memory copy speed most of the time, with synchronous writes > > only done when > > needed. The embedded platform you're using probably writes straight to > > FLASH, which is necassarily a synchronous operation if your OS doesn't > > have a cache between your app and the FLASH FS. While flash > > writes are low > > latency, they are also low bandwidth, and won't be within an order of > > magnitude of performance when compared to a desktop PC write to OS > > filesystem cache. > > > > Finally, you give no indication on the actual CPU speed of > > the embedded > > platform. It's quite reasonable to assume a development PC could be an > > order of magnitude faster on sheer integer throughput. I'm > > amazed how slow > > my 50MHz microSPARC based SPARCclassic is. Such a platform > > would not be > > much, if at all, slower than a modern embedded platform, and has the > > benefit of gobs of RAM, but still runs the same code two orders of > > magnitude slower at least than my Athlon XP 1700 based > > desktop. You have > > to keep your performance expectations realistic. You are, afterall, > > running a complete, ACID transaction, SQL relational database. > > > The maximum CPU speed of our ARM7 chip is 71Mhz. > > > Others have indicated that dropping indexes might help when > > deleting or > > inserting records. However, have you tried simply not having > > indexes at > > all? Would that cause unacceptable slowdown? Perhaps, for the > > demo query > > from the original post, just keep the DATE index on > > EXAMINATIONS, and use > > full table scans for queries based on EXAM_TYPE and > > STATUS_FLAG. Truth is, > > given the small number of EXAM_TYPE and STATUS_FLAG values (I > > presume), > > you're as well just doing table scans when looking for > > specific exam types > > and statuses. Indexes only really help when you have a large > > variation in > > values with few collisions. Doing this will leave a single > > index update in > > addition to the actual row removals, which should improve performance. > > I have tried permanently dropping the indexes on EXAM_TYPE and STATUS_FLAG > and this gives some improvement in time. Indeed it does seem that the > STATUS_FLAG index is worthless and in the initial version of the software we > will have only 1 EXAM_TYPE (although this will increase for each module we > release over the next few months). > > I have also tried the suggested method of dropping the > EXAM_PATIENT_ID_INDEX index on the examinations table before delete and > rebuilding it on completion. I cannot delete the remaining indexes as they > are used during the delete operation and this slows the whole operation > down. > > The latest changes have reduced the time to delete the same number of > records from 3:45 minutes to 2:53 minutes. Still a long time to wait but any > time saving is welcome, especially as the test is for a 50% full scenario so > at 99% we can expect it to take 6 minutes. > > Thanks again for your help. > > If there are any other ideas on how we can optimise this further then > please let me know. > > > Mark > > > DISCLAIMER: > This information and any attachments contained in this email message is > intended only for the use of the
RE: [sqlite] Very Slow delete times on larger databases, please help!
Thanks to both Christian Smith and John Stanton for your posts. > On Wed, 19 Oct 2005, Christian Smith wrote: > From the VDBE output you originally posted, you are doing a > fair amount of > work for each deleted row: > - Index search to find the next row from EXAMINATIONS to delete > - Removing the row from 3 indexes on EXAMINATIONS > - (trigger) Remove related row in SPIRO_TEST from 2 indexes > on SPIRO_TEST > - (trigger) Remove related row in SPIRO_TEST > - Remove the row from EXAMINATIONS > > Check your cache size. If the above work is causing the 75 page entry > cache to thrash, you're likely to hit worst case performance as the > thrashing pages may be being accessed in a cyclical fashion. > Not sure how > like it is that your page cache is not big enough. How big is a row of > data, typically? Our cache size is 75 pages of 8192 bytes = 600Kb. The maximum size of an EXAMINATIONS record is about 500 bytes, 450 bytes of this is a varchar field. In the test example the average size of an EXAMINATIONS record is 60 bytes as not much text is saved. The maximum size of a SPIRO_TEST record is about 5Kb, these will vary from test to test, but for the test example the size of each SPIRO_TEST record is fixed to approx 1Kb. Based on this I dont think that we should be thrashing the cache. I am however unsure how SQlite works here. > Also, a 60x slowdown is not to be unexpected. The PC version, while > probably having the same SQLite page cache size in the SQLite > app itself, > will most likely be reading and writing to the OSes cache at memory to > memory copy speed most of the time, with synchronous writes > only done when > needed. The embedded platform you're using probably writes straight to > FLASH, which is necassarily a synchronous operation if your OS doesn't > have a cache between your app and the FLASH FS. While flash > writes are low > latency, they are also low bandwidth, and won't be within an order of > magnitude of performance when compared to a desktop PC write to OS > filesystem cache. > > Finally, you give no indication on the actual CPU speed of > the embedded > platform. It's quite reasonable to assume a development PC could be an > order of magnitude faster on sheer integer throughput. I'm > amazed how slow > my 50MHz microSPARC based SPARCclassic is. Such a platform > would not be > much, if at all, slower than a modern embedded platform, and has the > benefit of gobs of RAM, but still runs the same code two orders of > magnitude slower at least than my Athlon XP 1700 based > desktop. You have > to keep your performance expectations realistic. You are, afterall, > running a complete, ACID transaction, SQL relational database. The maximum CPU speed of our ARM7 chip is 71Mhz. > Others have indicated that dropping indexes might help when > deleting or > inserting records. However, have you tried simply not having > indexes at > all? Would that cause unacceptable slowdown? Perhaps, for the > demo query > from the original post, just keep the DATE index on > EXAMINATIONS, and use > full table scans for queries based on EXAM_TYPE and > STATUS_FLAG. Truth is, > given the small number of EXAM_TYPE and STATUS_FLAG values (I > presume), > you're as well just doing table scans when looking for > specific exam types > and statuses. Indexes only really help when you have a large > variation in > values with few collisions. Doing this will leave a single > index update in > addition to the actual row removals, which should improve performance. I have tried permanently dropping the indexes on EXAM_TYPE and STATUS_FLAG and this gives some improvement in time. Indeed it does seem that the STATUS_FLAG index is worthless and in the initial version of the software we will have only 1 EXAM_TYPE (although this will increase for each module we release over the next few months). I have also tried the suggested method of dropping the EXAM_PATIENT_ID_INDEX index on the examinations table before delete and rebuilding it on completion. I cannot delete the remaining indexes as they are used during the delete operation and this slows the whole operation down. The latest changes have reduced the time to delete the same number of records from 3:45 minutes to 2:53 minutes. Still a long time to wait but any time saving is welcome, especially as the test is for a 50% full scenario so at 99% we can expect it to take 6 minutes. Thanks again for your help. If there are any other ideas on how we can optimise this further then please let me know. Mark DISCLAIMER: This information and any attachments contained in this email message is intended only for the use of the individual or entity to which it is addressed and may contain information that is privileged, confidential, and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, or the employee or agent responsible for delivering the message to the intended
RE: [sqlite] Very Slow delete times on larger databases, please help!
On Wed, 19 Oct 2005, Allan, Mark wrote: >We are able to compile our application for both target and host. When >compiled for host the application runs on Win32 and will >create/read/write to a database file on the host PC. > >The performance of the deletions on Win32 will not take the 11 minutes I >specified, this is only a problem for our target. The same operation on >the PC will take only 3-4 seconds. Please note that since my first email >we have tried increasing the page size of SQLite and have increased the >page size from 1024 bytes to 8192 bytes. This has decreased the time to >process the same delete operation from 11 minutes to 3.75 minutes on our >target hardware. Both host and target versions of the software use the >same configuration a page size of 8192 bytes and a cache of 75 pages = >600k. > >The only real differences are 1) the hardware, 2) the filing system. We >would expect a difference in performance as the PC is much faster than >our target hardware and the write speed to NOR flash is comparatively >slow but not as drastic a drop-off as we see. 3-4 seconds -> 3-4 minutes. >From the VDBE output you originally posted, you are doing a fair amount of work for each deleted row: - Index search to find the next row from EXAMINATIONS to delete - Removing the row from 3 indexes on EXAMINATIONS - (trigger) Remove related row in SPIRO_TEST from 2 indexes on SPIRO_TEST - (trigger) Remove related row in SPIRO_TEST - Remove the row from EXAMINATIONS Check your cache size. If the above work is causing the 75 page entry cache to thrash, you're likely to hit worst case performance as the thrashing pages may be being accessed in a cyclical fashion. Not sure how like it is that your page cache is not big enough. How big is a row of data, typically? Also, a 60x slowdown is not to be unexpected. The PC version, while probably having the same SQLite page cache size in the SQLite app itself, will most likely be reading and writing to the OSes cache at memory to memory copy speed most of the time, with synchronous writes only done when needed. The embedded platform you're using probably writes straight to FLASH, which is necassarily a synchronous operation if your OS doesn't have a cache between your app and the FLASH FS. While flash writes are low latency, they are also low bandwidth, and won't be within an order of magnitude of performance when compared to a desktop PC write to OS filesystem cache. Finally, you give no indication on the actual CPU speed of the embedded platform. It's quite reasonable to assume a development PC could be an order of magnitude faster on sheer integer throughput. I'm amazed how slow my 50MHz microSPARC based SPARCclassic is. Such a platform would not be much, if at all, slower than a modern embedded platform, and has the benefit of gobs of RAM, but still runs the same code two orders of magnitude slower at least than my Athlon XP 1700 based desktop. You have to keep your performance expectations realistic. You are, afterall, running a complete, ACID transaction, SQL relational database. > >It may be useful for us to know what SQLite is doing during deletion so >that we can try and optimise our code and/or any configuration of SQLite, >our filesystem code or the hardware to try and get this figure down. Can >anyone give me a reasonably detailed description of what is happening >during delete. The documentation on the website has not helped us >diagnose where our problem lies. Others have indicated that dropping indexes might help when deleting or inserting records. However, have you tried simply not having indexes at all? Would that cause unacceptable slowdown? Perhaps, for the demo query from the original post, just keep the DATE index on EXAMINATIONS, and use full table scans for queries based on EXAM_TYPE and STATUS_FLAG. Truth is, given the small number of EXAM_TYPE and STATUS_FLAG values (I presume), you're as well just doing table scans when looking for specific exam types and statuses. Indexes only really help when you have a large variation in values with few collisions. Doing this will leave a single index update in addition to the actual row removals, which should improve performance. > >Best Regards > >Mark > Christian > > >-Original Message- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] >Sent: 18 October 2005 19:06 >To: sqlite-users@sqlite.org >Subject: Re: [sqlite] Very Slow delete times on larger databases, please >help! > > >"Allan, Mark" <[EMAIL PROTECTED]> wrote: >> Have you been able to investigate this yet? > >I have investigated and I found nothing wrong. I am unable >to reproduce the problem. >-- >D. Richard Hipp <[EMAIL PROTECTED]> > > > > >DISCLAIMER: >This information and any attachments contained in this email message is >
Re: [sqlite] Very Slow delete times on larger databases, please help!
This may or may not help, depending upon your schema. We find in general that insertions and deletions are the major overhead in index maintenance and there is a point where it is cheaper to drop the indices you are not using and rebuild them rather than to involve the high overhead of repeated B-Tree rebalancing etc. The drop and rebuild has the added benefit of ending up with an optimally organized index free from fragmentation. The cost of insertions and deletions in an index is not linear with index size. I haven't looked at the Sqlite B-Tree algorithms, so this I can only suggest this as an experiment. If Sqlite uses some form of B-Tree optimization, the overhead of insertions and deletions is greater and the drop and rebuild more likely to be an improvement. JS Allan, Mark wrote: We are able to compile our application for both target and host. When compiled for host the application runs on Win32 and will create/read/write to a database file on the host PC. The performance of the deletions on Win32 will not take the 11 minutes I specified, this is only a problem for our target. The same operation on the PC will take only 3-4 seconds. Please note that since my first email we have tried increasing the page size of SQLite and have increased the page size from 1024 bytes to 8192 bytes. This has decreased the time to process the same delete operation from 11 minutes to 3.75 minutes on our target hardware. Both host and target versions of the software use the same configuration a page size of 8192 bytes and a cache of 75 pages = 600k. The only real differences are 1) the hardware, 2) the filing system. We would expect a difference in performance as the PC is much faster than our target hardware and the write speed to NOR flash is comparatively slow but not as drastic a drop-off as we see. 3-4 seconds -> 3-4 minutes. It may be useful for us to know what SQLite is doing during deletion so that we can try and optimise our code and/or any configuration of SQLite, our filesystem code or the hardware to try and get this figure down. Can anyone give me a reasonably detailed description of what is happening during delete. The documentation on the website has not helped us diagnose where our problem lies. Best Regards Mark -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: 18 October 2005 19:06 To: sqlite-users@sqlite.org Subject: Re: [sqlite] Very Slow delete times on larger databases, please help! "Allan, Mark" <[EMAIL PROTECTED]> wrote: Have you been able to investigate this yet? I have investigated and I found nothing wrong. I am unable to reproduce the problem. -- D. Richard Hipp <[EMAIL PROTECTED]> DISCLAIMER: This information and any attachments contained in this email message is intended only for the use of the individual or entity to which it is addressed and may contain information that is privileged, confidential, and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, or the employee or agent responsible for delivering the message to the intended recipient, you are hereby notified that any dissemination, distribution, forwarding, or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by return email, and delete the original message immediately.
RE: [sqlite] Very Slow delete times on larger databases, please help!
We are able to compile our application for both target and host. When compiled for host the application runs on Win32 and will create/read/write to a database file on the host PC. The performance of the deletions on Win32 will not take the 11 minutes I specified, this is only a problem for our target. The same operation on the PC will take only 3-4 seconds. Please note that since my first email we have tried increasing the page size of SQLite and have increased the page size from 1024 bytes to 8192 bytes. This has decreased the time to process the same delete operation from 11 minutes to 3.75 minutes on our target hardware. Both host and target versions of the software use the same configuration a page size of 8192 bytes and a cache of 75 pages = 600k. The only real differences are 1) the hardware, 2) the filing system. We would expect a difference in performance as the PC is much faster than our target hardware and the write speed to NOR flash is comparatively slow but not as drastic a drop-off as we see. 3-4 seconds -> 3-4 minutes. It may be useful for us to know what SQLite is doing during deletion so that we can try and optimise our code and/or any configuration of SQLite, our filesystem code or the hardware to try and get this figure down. Can anyone give me a reasonably detailed description of what is happening during delete. The documentation on the website has not helped us diagnose where our problem lies. Best Regards Mark -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: 18 October 2005 19:06 To: sqlite-users@sqlite.org Subject: Re: [sqlite] Very Slow delete times on larger databases, please help! "Allan, Mark" <[EMAIL PROTECTED]> wrote: > Have you been able to investigate this yet? I have investigated and I found nothing wrong. I am unable to reproduce the problem. -- D. Richard Hipp <[EMAIL PROTECTED]> DISCLAIMER: This information and any attachments contained in this email message is intended only for the use of the individual or entity to which it is addressed and may contain information that is privileged, confidential, and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, or the employee or agent responsible for delivering the message to the intended recipient, you are hereby notified that any dissemination, distribution, forwarding, or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by return email, and delete the original message immediately.
Re: [sqlite] Very Slow delete times on larger databases, please help!
"Allan, Mark" <[EMAIL PROTECTED]> wrote: > Have you been able to investigate this yet? I have investigated and I found nothing wrong. I am unable to reproduce the problem. -- D. Richard Hipp <[EMAIL PROTECTED]>
RE: [sqlite] Very Slow delete times on larger databases, please help!
Have you been able to investigate this yet? Any ideas or recommendations? I sent you the analyzer output to [EMAIL PROTECTED] as it was too large to post on here. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: 12 October 2005 14:58 To: sqlite-users@sqlite.org Subject: Re: [sqlite] Very Slow delete times on larger databases, please help! "Allan, Mark" <[EMAIL PROTECTED]> wrote: > We are experiencing incredibly slow delete times when deleting a > large number of rows:- > > We are using SQLite on an embdedded platform with an ARM7 processor, > 2Mb RAM and 32Mb NOR Flash memory 25Mb of which is allocated for > storage for our database. > What operating system? Can you send the output of sqlite3_analyzer run against your database file prior to doing the delete? Have you tried upgrading to a later version of SQLite? -- D. Richard Hipp <[EMAIL PROTECTED]> DISCLAIMER: This information and any attachments contained in this email message is intended only for the use of the individual or entity to which it is addressed and may contain information that is privileged, confidential, and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, or the employee or agent responsible for delivering the message to the intended recipient, you are hereby notified that any dissemination, distribution, forwarding, or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by return email, and delete the original message immediately.
