A proper backup program that opened the file for r/o, non-exclusive use may be able to copy the file.
I thought SQLite has a live backup capability now. Surely that is the best way to handle this. Wednesday, July 8, 2009, 6:16:41 PM, you wrote: JS> It looks like you are trying to copy from a process other than the one JS> which holds the lock. JS> Think abnout it - the lock gives exlusive access to the file to the JS> process which sets it and blocks all other processes. JS> Stan Bielski wrote: >> Just to make sure I understood you correctly, is this what you are >> suggesting? >> >> * Open file with sqlite app (in my case sqlite3) >> * execute BEGIN EXCLUSIVE TRANSACTION; >> * initiate the file copy >> * COMMIT; after the copy is finished. >> >> I tried doing this, but very early into the copy Windows issues the >> following error: >> >> Errror 0x80070021: The process cannot access the file because another >> process has locked a portion of the file. >> >> >> On Tue, Jul 7, 2009 at 1:03 PM, John Stanton<jo...@viacognis.com> wrote: >> >>> You should synchronize your backup (copy). Try surrounding it with an >>> exclusive transaction. >>> >>> Stan Bielski wrote: >>> >>>> Sorry for the repost, but the original thread was hijacked by another >>>> list user. This is a serious problem IMHO; it looks like the DB can't >>>> be backed-up without rendering the machine unusable if a query hits it >>>> while a copy is in progress. >>>> >>>> Hello, >>>> >>>> In the course of copying a largish (20 GB) database file while >>>> accessing it via sqlite3, the machine became very unresponsive. I >>>> opened task manager and found that the system was using a huge amount >>>> of virtual memory, causing it to thrash. Per-process memory usage >>>> looked normal and did not add up to anywhere near system-wide VM >>>> usage. >>>> >>>> I ran into this issue at a customer site and was able to reproduce it >>>> using a local Windows 2008 installation. I have not installed any >>>> backup software or a virus scanner. Storage is local disk, SQLite >>>> version is 3.3.17. >>>> >>>> At first I thought that this was a general Windows problem involving a >>>> process accessing a file that is being copied, but other binaries I >>>> tested do not cause the same behavior that sqlite3 does. I performed >>>> the following experiments to try to diagnose the issue. >>>> >>>> Case 1: >>>> >>>> * I copy a 20 GB sqlite DB using Windows' own copy utility (e.g. via >>>> explorer). >>>> * At any point during the copy, I open the file being copied in sqlite3 >>>> * I exit sqlite3. >>>> * During the rest of the copy the OS will consume virtual memory >>>> linear (seemingly identical) to the amount of data copied since the >>>> process opened the file. >>>> >>>> I repeated this experiment using a similarly-sized file created from >>>> /dev/zero (i.e. an invalid DB) and the results were the same. >>>> >>>> Case 2: >>>> >>>> * I copy the sqlite DB using Windows' own copy utility (e.g. via explorer). >>>> * At any point during the copy, I run 'strings' with the file as an >>>> argument. >>>> * I exit strings. >>>> * The copy does not result in the OS consuming additional virtual memory. >>>> >>>> Case 3: >>>> >>>> * I open the DB in sqlite3 >>>> * I let sqlite3 idle and do not input any commands. >>>> * I copy a sqlite DB using Windows' own copy utility (e.g. via explorer). >>>> * I continue to let sqlite3 idle and do not input any commands. >>>> * During the rest of the copy the OS will consume virtual memory >>>> linear (seemingly identical) to the amount of data copied since the >>>> process opened the file. >>>> >>>> Is there a workaround for this issue? Any assistance or info is >>>> appreciated. >>>> >>>> Thanks, >>>> -Stan -- Best regards, Neville Franks, http://www.surfulater.com http://blog.surfulater.com _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
