On Feb 25, 2010, at 10:19 AM, Rob Read 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. >
Probably this is due to memory fragmentation. In a low-memory environment, you should use sqlite3_config(SQLITE_CONFIG_PAGECACHE,...) to set up a separate buffer for use by the page cache. The page cache is the primary memory user, so allocate most of your memory budget to it. And since all page cache allocations are the same size, you won't get fragmentation there. You can normally get by with much less memory for the general-purpose heap, depending on how many prepared statements you are holding at once and how complex your schema is. > > > 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 D. Richard Hipp d...@hwaci.com _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
