On Tue, Nov 30, 2010 at 9:20 AM, Philip Martin <philip.mar...@wandisco.com> wrote: > Florian Weimer <fwei...@bfk.de> writes: > >> * Philip Martin: >> >>> An SQLite read blocks SQlite writes by other threads/processes, so >>> the long lived select may cause writes to fail that would otherwise >>> succeed. >> >> AFAIK, such blocking only happens inside SQLite if you are not in WAL >> mode and the write transaction has outgrown its cache size. > > WAL has limits, it doesn't work on network disks for example. In the > absence of WAL the cache only delays the block, when the write commits > it still requires an exclusive lock.
Also, savvy users could theoretically enable WAL on specific working copies without Subversion knowing or caring about it (so long as Subversion is using a recent enough sqlite). -Hyrum
