Hmm. I see that sqlite3PcacheReleaseMemory() is a no-op if sqlite3GlobalConfig.nPage is non-zero, and that happens when SQLITE_DEFAULT_PCACHE_INITSZ is not zero. If I compile with -DSQLITE_DEFAULT_PCACHE_INITSZ=0 , then I see the expected pages freed. AFAICT, it doesn't matter if you make use of more than SQLITE_DEFAULT_PCACHE_INITSZ pages, it still doesn't free the excess.
Looks like that was added in 3.8.11 back in July. -scott On Thu, Jan 7, 2016 at 5:44 AM, Bart Smissaert <bart.smissaert at gmail.com> wrote: > These are the compile flags of my sqlite3.dll: > > compile_option > ---------------------------------------------------- > DEBUG > ENABLE_COLUMN_METADATA > ENABLE_MEMORY_MANAGEMENT > MEMDEBUG > OMIT_LOOKASIDE > THREADSAFE=0 > > And these are the set pragma's: > > PRAGMA cache_size 32768 > PRAGMA default_cache_size 32768 > PRAGMA page_count 712711 > PRAGMA max_page_count 1073741823 > PRAGMA page_size 1024 > PRAGMA journal_size_limit -1 > PRAGMA locking_mode normal > PRAGMA automatic_index 1 > PRAGMA encoding UTF-8 > PRAGMA ignore_check_constraints 0 > PRAGMA read_uncommitted 0 > PRAGMA recursive_triggers 0 > PRAGMA reverse_unordered_selects 0 > PRAGMA secure_delete 0 > PRAGMA wal_autocheckpoint 1000 > PRAGMA writable_schema 0 > PRAGMA journal_mode off > PRAGMA auto_vacuum NONE > PRAGMA synchronous OFF > PRAGMA temp_store DEFAULT > > > RBS > > On Thu, Jan 7, 2016 at 1:39 PM, Bart Smissaert <bart.smissaert at gmail.com> > wrote: > > > > So you should > > see results if you start a transaction, do a few update statements, > commit > > the transaction, the call sqlite3_release_memory(db). > > > > I tried this with a large table, first with no transaction then with a > > transaction > > and tried the sqlite3_release_memory directly after the sqlite3_finalize, > > but in both cases result still zero: > > > > sqlite3_memory_used: 37190712 > > sqlite3_release_memory: 0 > > sqlite3_memory_used: 37190712 > > > > This was a single update, where I don't think a transaction is helpful. > > Still no idea how I can make sqlite3_release_memory produce non-zero. > > > > RBS > > > > > > > > On Thu, Jan 7, 2016 at 6:05 AM, Scott Hess <shess at google.com> wrote: > > > >> On Wed, Jan 6, 2016 at 3:03 PM, Bart Smissaert < > bart.smissaert at gmail.com> > >> wrote: > >> > >> > Have compiled sqlite3.dll (latest) compiled with > >> ENABLE_MEMORY_MANAGEMENT, > >> > but sofar > >> > not been able yet to make sqlite3_release_memory produce anything else > >> than > >> > 0. > >> > What would be the simplest way to make this happen? > >> > I don't want to do this with C coding, so it should be some SQL > >> scenario or > >> > to do with simple > >> > SQLite functions such as sqlite3_step, _prepare, -finalize etc. > >> > >> > >> Last time I was paying attention to this, I believe that I found that > the > >> biggest effect was to free unpinned pages from the page cache. So it > >> might > >> not free pages if you're in a transaction, for instance. I would guess > >> that if you had memory-mapped mode on and are doing only reads, there > >> would > >> be no pages to free (mmap pages aren't in the page cache). So you > should > >> see results if you start a transaction, do a few update statements, > commit > >> the transaction, the call sqlite3_release_memory(db). > >> > >> -scott > >> _______________________________________________ > >> sqlite-users mailing list > >> sqlite-users at mailinglists.sqlite.org > >> http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > >> > > > > > _______________________________________________ > sqlite-users mailing list > sqlite-users at mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users >
