On Mon, Dec 3, 2012 at 7:08 AM, Philip Martin <philip.mar...@wandisco.com>wrote:
> Prompted by a question on users I wondered how SQLite's vacuum > (http://sqlite.org/lang_vacuum.html) would affect wc.db size. On a > Subversion trunk working copy I have been using for months the size was > reduced from 2.3MB to 1.3MB which isn't really a significant change. > > For a further test I checked-out a ^/subversion/branches working copy > for a wc.db of 93MB with 121738 rows, I made it sparse with 66046 rows > and it was still 93MB, then I ran vacuum and it was reduced to 51MB. I > have a gcc working copy with some subtrees switched to an empty > directory. There vacuum reduced wc.db from 47MB to 8.1MB. > So it appears that vacuum is interesting if the number of rows decreases > dramatically. > > SQLite has auto_vacuum but it comes with a warning that it may make > fragmentation worse (http://sqlite.org/pragma.html#pragma_auto_vacuum) > so it's not clear whether we should enable it. Perhaps we should add a > "vacuum" to cleanup? A full vacuum rewrites all the tables so it's not > a trivial operation but it is reasonably fast for the working copies on > local disk that I tried. > I think adding "vacuum" to cleanup is a reasonable first step. "cleanup" is an explicit operation that a user could reasonably expect to take some non-trivial amount of time. We already remove unneeded pristines during cleanup, might as well do the same thing with wc.db space. -Hyrum
