Alvaro Herrera wrote: > > Excerpts from Bruce Momjian's message of jue nov 10 16:59:20 -0300 2011: > > Alvaro Herrera wrote: > > > Hello, > > > > > > After some rather extensive rewriting, I submit the patch to improve > > > foreign key locks. > > > > > > To recap, the point of this patch is to introduce a new lock tuple mode, > > > that lets the RI code obtain a lighter lock on tuples, which doesn't > > > conflict with updates that do not modify the key columns. > > > > What kind of operations benefit from a non-key lock like this? > > I'm not sure I understand the question. > > With this patch, a RI check does "SELECT FOR KEY SHARE". This means the > tuple is locked with that mode until the transaction finishes. An > UPDATE that modifies the referenced row will not conflict with that lock. > > An UPDATE that modifies the key columns will be blocked, just as now. > Same with a DELETE.
OK, so it prevents non-key data modifications from spilling to the referred rows --- nice. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
