Hi, I am a Google soc student and in need of some help with PostgreSQL internals:
My C function can run (and already running) for a very very long time on some inputs and reiterate on relations using SPI. Basically, I open portals and cursors to relations. Also note that I always open the relations in READ ONLY mode using SPI. A big no no is that some data in the relations would change since that would just ruin everything. I have a great need to identify a tuple uniquely so my prototype uses the CTID field for that purpose. Btw, this identification is required by the algorithm and primary keys are just wasteful and will slow the process considerably (not to mention some relations don't have primary keys). The question is, can the CTID field change throughout the run of my function due to some other processes working on the relation? Or because of command boundaries it is pretty much secured inside an implicit transaction? The problem wasn't so great if I didn't want to exploit indices in the relations (but I do and does), since after you issue a SELECT that uses indices, all you can rely on is the CTID to uniquely identify a tuple. The other solution is to temporarily duplicate the relations but this is less appealing (plus it's already working great with CTIDs). -- Tzahi Fadida Blog: http://tzahi.blogsite.org | Home Site: http://tzahi.webhop.info WARNING TO SPAMMERS: see at http://members.lycos.co.uk/my2nis/spamwarning.html ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
