-----Original Message----- From: Tom Lane [mailto:[EMAIL PROTECTED]] Sent: Friday, April 05, 2002 11:37 AM To: Doug McNaught Cc: Dann Corbit; [EMAIL PROTECTED] Subject: Re: [HACKERS] Suggestion for optimization
Doug McNaught <[EMAIL PROTECTED]> writes: > "Dann Corbit" <[EMAIL PROTECTED]> writes: >> It would be nice if total table cardinality could be maintained live. > How would this work with MVCC? It wouldn't. That's why it's not there. Under MVCC, table cardinality is in the eye of the beholder... >>------------------------- If this is true (even after a commit) then MVCC is a very bad thing. No transactions occur, and two people ask the same question yet get different answers. Doesn't that scare anyone? That would mean (among other things) that Postgresql cannot be used for a data warehouse. One of the primary facets of a reliable database transaction system is repeatability. In fact, if there is no certain cardinality known after commits, then there are no reliable database operations that can be trusted. How many accounts are 90 days overdue? Bill says 78 and Frank says 82. Who is right and how can we know? I have spent months working on Postgresql projects here (at CONNX Solutions Inc.) and talked management into using an open source database. Please tell me I'm not going to look like a bloody idiot in the near term. <<------------------------- ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
