what's hash-join
Hi Rukmini could tell me what's that hash-join GSK Rukmini DeviTo: Multiple recipients of list ORACLE-L rukmini@indb[EMAIL PROTECTED] rain.comcc: 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).
Re: what's hash-join
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 DeviTo: Multiple recipients of list ORACLE-L rukmini@indb [EMAIL PROTECTED] rain.comcc: 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
RE: what's hash-join
Huh? Is this jeporady? Walking on water and developing software from a specification are easy if both are frozen. Christopher R. Spence Oracle DBA Fuelspot -Original Message- Sent: Thursday, May 31, 2001 6:00 AM To: Multiple recipients of list ORACLE-L Probably a cartesian product Roland S -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: 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: Christopher Spence 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).
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 DeviTo: Multiple recipients of list ORACLE-L rukmini@indb [EMAIL PROTECTED] rain.comcc: 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]
RE: what's hash-join
Kev: How well a HASH join works depends on the data you are working with. In my experience it works best when you are joining a large table against a very small table. I've seen up to 50% improvement when I forced the optimizer to use HASH joins instead of Nested Loops or Merge Joins Kevin -Original Message- Sent: Thursday, May 31, 2001 9:34 AM To: Multiple recipients of list ORACLE-L 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 DeviTo: Multiple recipients of list ORACLE-L rukmini@indb [EMAIL PROTECTED] rain.comcc: 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
RE: what's hash-join
It will perform better than sort and merge and nested loops in most cases. They tend to be fast. But will not out perform index nested loops in most cases. Although in some cases a sort and merge can out perform a hash join. Walking on water and developing software from a specification are easy if both are frozen. Christopher R. Spence Oracle DBA Fuelspot -Original Message- Sent: Thursday, May 31, 2001 9:34 AM To: Multiple recipients of list ORACLE-L 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 DeviTo: Multiple recipients of list ORACLE-L rukmini@indb [EMAIL PROTECTED] rain.comcc: 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
RE: what's hash-join
Title: RE: what's hash-join 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
Re: what's hash-join
And it will skip partitions that it can see will not match any other corresponding partition. PD Miller wrote: At 0:16 -0800 31/5/01, Senthil Ganapathi wrote: could tell me what's that hash-join Straight from the concepts manual: To perform a hash join, Oracle follows these steps: 1. Oracle performs a full table scan on each of the tables and splits each into as many partitions as possible based on the available memory. 2. Oracle builds a hash table from one of the partitions (if possible, Oracle will select a partition that fits into available memory). Oracle then uses the corresponding partition in the other table to probe the hash table. All partition pairs that do not fit into memory are placed onto disk. 3. For each pair of partitions (one from each table), Oracle uses the smaller one to build a hash table and the larger one to probe the hash table. Or to paraphrase: load each table into a set of hash partitions based on the equi-join predicate. Use the smaller hash partition hash values to find the matches in the larger.RegardsPaul Miller -- - Carib Data Limited mailto:[EMAIL PROTECTED]> http://www.caribdata.co.uk> -- Venlig hilsen Mogens Nrgaard Technical Director Miracle A/S, Denmark Web: http://MiracleAS.dk Mobile: +45 2527 7100
RE: what's hash-join
The general school of thought is joining a large table to a small one. There is an article on Metalink thats a little out of date now, but it describes the good/the bad, and tuning of hash joins. Look for doc 67134.1 and 41954.1 hth connor --- Kevin Kostyszyn [EMAIL PROTECTED] wrote: 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 DeviTo: Multiple recipients of list ORACLE-L rukmini@indb [EMAIL PROTECTED] rain.comcc: 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 === message truncated === = 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
Re: what's hash-join
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 worksfaster 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 mergeHash 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) 538-5051San Diego, California -- Public Internet access / Mailing Lists To REMOVE yourself from this mailing list, send an E-Mail messageto: [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)
