Re: what's hash-join

[Shevtsov, Eduard]

Title: RE: what's hash-join

Hi Lisa,   You're correct. I'm sure you know, but I'd like to add that hash join usually works faster than over methods when there are no good selective conditions in the clause WHERE.   Regards, Ed   Hi Kevin, It's quick if you have the temp space to support it.  however with larger tables my experience has been that it blows temp, isn't that much faster even if you do have the temp space, and in most cases you are better off with index-driven nested loops join.  It works well with small to medium-sized tables. Just my .02 List, if I'm wrong, please correct me. Lisa Koivu Oracle Database Administrator 954-935-4117 The information in the electronic mail message is Cendant confidential and may be legally privileged, it is intended solely for the addressee(s) access to this internet electronic mail message by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken or omitted to be taken in reliance on it is prohibited and may be unlawful. The sender believes that this E-mail and any attachments were free of any virus, worm, Trojan horse, and/or malicious code when sent. This message and its attachments could have been infected during transmission. By reading the message and opening any attachments, the recipient accepts full responsibility for taking protective and remedial action about viruses and other defects. Cendant Corporation or Affiliates are not liable for any loss or damage arising in any way from this message or its attachments. -----Original Message----- From:   Kevin Kostyszyn [SMTP:[EMAIL PROTECTED]] Sent:   Thursday, May 31, 2001 9:34 AM To:     Multiple recipients of list ORACLE-L Subject:        RE: what's hash-join What's the performance (gain/loss) on such a join, when would you want to use one? Kev -----Original Message----- McDonald Sent: Thursday, May 31, 2001 6:00 AM To: Multiple recipients of list ORACLE-L A method of joining two tables.  You scan each and use a hashing algorithm to isolate/match keys. hth connor --- Senthil Ganapathi <[EMAIL PROTECTED]> wrote: > > Hi Rukmini > could tell me what's that hash-join > > GSK > > > > >                     "Rukmini > >                     Devi"                To: > Multiple recipients of list ORACLE-L >                     <rukmini@indb > <[EMAIL PROTECTED]> >                     rain.com>            cc: > >                     Sent by:             Subject: >  Re: 4 join methods? >                     root@fatcity. > >                     com > > > > > >                     31-05-01 > >                     09:55 AM > >                     Please > >                     respond to > >                     ORACLE-L > > > > > > > > > > 1. Equi-join     2. Self-join     3. Outer-join  4. > Hash-join > > rukmini > ----- Original Message ----- > To: "Multiple recipients of list ORACLE-L" > <[EMAIL PROTECTED]> > Sent: Thursday, May 31, 2001 11:20 AM > > > > i feel the fourth one is self join. > > > > ----- Original Message ----- > > To: Multiple recipients of list ORACLE-L > <[EMAIL PROTECTED]> > > Sent: Thursday, May 31, 2001 8:10 AM > > > > > > > Hi, > > > > > > I just read there are four join methods.  I know > three: > > > > > > Nested loops > > > Sort merge > > > Hash join > > > > > > What's the fourth? > > > > > > - Greg > > > > > > -- > > > Please see the official ORACLE-L FAQ: > http://www.orafaq.com > > > -- > > > Author: Greg Moore > > >   INET: [EMAIL PROTECTED] > > > > > > Fat City Network Services    -- (858) 538-5051 > FAX: (858) 538-5051 > > > San Diego, California        -- Public Internet > access / Mailing Lists > > > > -------------------------------------------------------------------- > > > To REMOVE yourself from this mailing list, send > an E-Mail message > > > to: [EMAIL PROTECTED] (note EXACT spelling of > 'ListGuru') and in > > > the message BODY, include a line containing: > UNSUB ORACLE-L > > > (or the name of mailing list you want to be > removed from).  You may > > > also send the HELP command for other information > (like subscribing). > > > > -- > > Please see the official ORACLE-L FAQ: > http://www.orafaq.com > > -- > > Author: Saurabh Sharma > >   INET: [EMAIL PROTECTED] > > > > Fat City Network Services    -- (858) 538-5051 > FAX: (858) 538-5051 > > San Diego, California        -- Public Internet > access / Mailing Lists > > > -------------------------------------------------------------------- > > To REMOVE yourself from this mailing list, send an > E-Mail message > > to: [EMAIL PROTECTED] (note EXACT spelling of > 'ListGuru') and in > > the message BODY, include a line containing: UNSUB > ORACLE-L > > (or the name of mailing list you want to be > removed from).  You may > > also send the HELP command for other information > (like subscribing). > > -- > Please see the official ORACLE-L FAQ: > http://www.orafaq.com > -- > Author: Rukmini Devi >   INET: [EMAIL PROTECTED] > > Fat City Network Services    -- (858) 538-5051  FAX: > (858) 538-5051 > San Diego, California        -- Public Internet > access / Mailing Lists > -------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an > E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of > 'ListGuru') and in > the message BODY, include a line containing: UNSUB > ORACLE-L > (or the name of mailing list you want to be removed > from).  You may > also send the HELP command for other information > (like subscribing). > > > > > -- > Please see the official ORACLE-L FAQ: > http://www.orafaq.com > -- > Author: Senthil Ganapathi >   INET: [EMAIL PROTECTED] > > Fat City Network Services    -- (858) 538-5051  FAX: > (858) 538-5051 > San Diego, California        -- Public Internet > access / Mailing Lists > -------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an > E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of > 'ListGuru') and in > the message BODY, include a line containing: UNSUB > ORACLE-L > (or the name of mailing list you want to be removed > from).  You may > also send the HELP command for other information > (like subscribing). ===== Connor McDonald http://www.oracledba.co.uk (mirrored at http://www.oradba.freeserve.co.uk) "Some days you're the pigeon, some days you're the statue" ____________________________________________________________ Do You Yahoo!? Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk or your free @yahoo.ie address at http://mail.yahoo.ie -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: =?iso-8859-1?q?Connor=20McDonald?=   INET: [EMAIL PROTECTED] Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051 San Diego, California        -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from).  You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Kevin Kostyszyn   INET: [EMAIL PROTECTED] Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051 San Diego, California        -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from).  You may also send the HELP command for other information (like subscribing).