Return-Path: owner-postman Received: from localhost (localhost [127.0.0.1]) by nobozo.CS.Berkeley.EDU (8.6.4/8.6.3) with SMTP id GAA00605 for postgres-dist; Thu, 11 Nov 1993 06:37:45 -0800 Resent-From: POSTGRES mailing list Resent-Message-Id: <199311111437.GAA00605@nobozo.CS.Berkeley.EDU> X-Authentication-Warning: nobozo.CS.Berkeley.EDU: Host localhost didn't use HELO protocol Sender: owner-postman@postgres.Berkeley.EDU X-Return-Path: owner-postman Received: from fel.tno.nl (tnofel.fel.tno.nl [192.55.105.65]) by nobozo.CS.Berkeley.EDU (8.6.4/8.6.3) with SMTP id GAA00596 for ; Thu, 11 Nov 1993 06:37:39 -0800 Received: by fel.tno.nl id AA12842 (5.65c/IDA-1.4.3 for postgres@postgres.berkeley.edu); Thu, 11 Nov 1993 15:38:44 +0100 From: Peter van Oosterom Message-Id: <199311111438.AA12842@fel.tno.nl> Subject: rewrite rule To: postgres@postgres.Berkeley.EDU Date: Thu, 11 Nov 93 15:38:44 MET X-Mailer: ELM [version 2.3 PL11] Resent-To: postgres-dist@postgres.Berkeley.EDU Resent-Date: Thu, 11 Nov 93 06:37:41 -0800 Resent-XMts: smtp Dear Postgres-group, There seams to be an error in the "rewrite rule" system. Consider the following example; create, fill, and inspect a relation: create rel(a=text, b=int4)\g append rel(a="AAB", b=10)\g append rel(a="HLP", b=3)\g retrieve (rel.all)\g This gives: ----------------------------- | a | b | ----------------------------- | HLP | 3 | ----------------------------- | AAB | 10 | ----------------------------- Now define a rule to change "AAB" into "Y" and inspect the relation again: define rewrite rule r1 is on retrieve to rel.a where current.a = "AAB" do instead retrieve (a = "Y")\g retrieve (rel.all)\g This gives: ----------------------------- | a | b | ----------------------------- | Y | 3 | ----------------------------- | Y | 10 | ----------------------------- Note that "HLP" is also changed into "Y", which should not be the case. More testing reveals that every string is converted to "Y". However, using an "instance rule" instead of a "rewrite rule" works fine: remove rewrite rule r1\g define instance rule r2 is on retrieve to rel.a where current.a = "AAB" do instead retrieve (a = "Y")\g retrieve (rel.all)\g This gives: ----------------------------- | a | b | ----------------------------- | HLP | 3 | ----------------------------- | Y | 10 | ----------------------------- This is the right result. Can somebody tell me what is wrong with the rewrite rule (or perhaps what did I do wrong with the rewrite rule)? Kind regards, Peter van Oosterom (oosterom@fel.tno.nl)