2011/6/1 Robert Haas <robertmh...@gmail.com>: > On Tue, May 31, 2011 at 7:04 AM, Cédric Villemain > <cedric.villemain.deb...@gmail.com> wrote: >> Robert, I wonder if all the logic with INIT_FORK is only to simulate >> truncate on server restart ? > > That is correct. > >> I failled to understand why not simply use truncate around the server >> start (when it is in recovery). > > We need to do the equivalent of a truncate but without relying in any > way on the system catalogs. The startup process is not bound to a > database, and starting a separate worker process for each database > would be both very complicated and very expensive. > > Also note that while truncate is very simple for a table (just zero > out the file) it's not so simple for an index (a zero-length file is > an invalid index, not an empty one). > >> While here I also wonder why GiST unlogged are not supported ?! > > Because they use LSNs internally to guarantee proper synchronization, > which presumes that WAL records are being omitted. Temporary GIST > indexes were broken too, for the same reason, but Heikki fixed that > using GetXLogRecPtrForTemp(). We could engineer a similar solution > for unlogged GIST indexes using a shared counter that is saved in > pg_control across clean shutdowns, but I think that's a 9.2 project. > > -- > Robert Haas > EnterpriseDB: http://www.enterprisedb.com > The Enterprise PostgreSQL Company >
All right, things under a new light! Thank you. -- Cédric Villemain 2ndQuadrant http://2ndQuadrant.fr/ PostgreSQL : Expertise, Formation et Support -- Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-bugs
