Could it be because of fragmentation issues? When you allow more cache pages to be allocated you allow more fragmentation to be introduced. And although in total there could be enough memory available there could still be no solid block of sufficient size available.
>From the comment in mem5.c: ============================ ** Let n be the size of the largest allocation divided by the minimum ** allocation size (after rounding all sizes up to a power of 2.) Let M ** be the maximum amount of memory ever outstanding at one time. Let ** N be the total amount of memory available for allocation. Robson ** proved that this memory allocator will never breakdown due to ** fragmentation as long as the following constraint holds: ** ** N >= M*(1 + log2(n)/2) - n + 1 ** ** The sqlite3_status() logic tracks the maximum values of n and M so ** that an application can, at any time, verify this constraint. ============================ Pavel On Thu, Feb 25, 2010 at 10:19 AM, Rob Read <r...@saltillo.com> wrote: > We are using sqlite in a low memory environment and as such have been using > the MEMSYS5 memory allocator. This has been working great to confine our > memory usage to the buffer that gets passed during start time. I have > recently run into some strange results while doing a step to insert a blob > into the database. If I set my cache size, using the pragma, to 1500 then > the step fails with SQLITE_NOMEM, but if I do this same process and decrease > the cache size to 1000 then the step succeeds. This might sound like a easy > problem to fix in that my page cache is taking up the memory that the step > needs to complete the insert, but if I check the memory usage by calling > sqlite3_memory_used(), in both situations I have plenty of memory available > to complete the transfer. If anyone could shed some light on this issue I > would appreciate it. > > > > Robert Read > > Lead Software Engineer > > Saltillo Corporation > > > > > > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
