FW: Unions slow in IDS 7.30

Posted in 1999

Willem Roos — Fri, 24 Sep 1999 00:44:14 +0200 — source: Informix-list mailing list archive (1991-1998)

This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ------_=_NextPart_001_01BF0615.2B1EE2AC Content-Type: text/plain; charset="iso-8859-1" Hmmm, Apologies for wasting your bandwidth, i have in the mean time figured it out. The union all eliminates the order by that would otherwise be done to take out the duplicates. The bit about it working fine under 7.23 is a lie - one that is apparently used often by users who wish to put pressure on their DBA after each upgrade. I'm starting to see through it :-) Regards > -----Original Message----- > From: Willem Roos > Sent: Friday, September 24, 1999 12:27 AM > To: 'Informix Mailing List' > Subject: Unions slow in IDS 7.30 > > > All, > > One of our users is running a query with a union consisting > of 2 subselects. The two subselects run fine on their own > (15 seconds). With a UNION they take more than a minute, > but with a UNION ALL they run their usual 15 seconds again. > The union vs. union all have identical query execution > plans - only the est. # of rows differs by a few hundred, > but the same cost. > > This used to be OK on 7.23 but seems to have broken on 7.30. > I've run update stats until blue in the face. Has anyone > seen this before. > > TIA > > /* ----------------------------------------------------- * > * Willem Roos (+27) 21 980 4941 * > * Forced to use M$ Outlook ## * > * ----------------------------------------------------- */ > ------_=_NextPart_001_01BF0615.2B1EE2AC Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"> <HTML> <HEAD> <META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; = charset=3Diso-8859-1"> <META NAME=3D"Generator" CONTENT=3D"MS Exchange Server version = 5.5.2448.0"> <TITLE>FW: Unions slow in IDS 7.30</TITLE> </HEAD> <BODY> Hmmm, Apologies for wasting your bandwidth, i have in the = mean time figured it out. The union all eliminates the order = by that would otherwise be done to take out the duplicates. = The bit about it working fine under 7.23 is a lie - one that = is apparently used often by users who wish to put pressure on = their DBA after each upgrade. I'm starting to see through it = :-) Regards > -----Original Message----- > From: Willem Roos > Sent: Friday, September 24, 1999 12:27 = AM > To: 'Informix Mailing List' > Subject: Unions slow in IDS 7.30 > > > All, > > One of our users is running a query with a = union consisting > of 2 subselects. The two subselects run fine on = their own > (15 seconds). With a UNION they take more than = a minute, > but with a UNION ALL they run their usual 15 = seconds again. > The union vs. union all have identical query = execution > plans - only the est. # of rows differs by a = few hundred, > but the same cost. > > This used to be OK on 7.23 but seems to have = broken on 7.30. > I've run update stats until blue in the face. = Has anyone > seen this before. > > TIA > > /* = ----------------------------------------------------- * >  * Willem = Roos           &n= bsp;           &n= bsp; (+27) 21 980 4941 * >  * Forced to use M$ Outlook = ##           &nbs= p;           &nbs= p;   * >  * = ----------------------------------------------------- */ > </BODY> </HTML> ------_=_NextPart_001_01BF0615.2B1EE2AC--

FW: Unions slow in IDS 7.30

Related threads

Your privacy choices