RE: Latch 'parallel query qref latch'
Jon, Thanks for the email. My next question is fairly obvious...I'm getting a lot of waits on this latch (up to 5% of all waits) - how do I tune it ? (We've got a pretty typical environment here, a few big tables with parallel degree 4, on a 2 cpu box with 2G of RAM, and only a couple of end users doing big queries)... Any guidelines (from anybody) would be much appreciated... TIA Ben From: Jon Walthour [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED] Subject: RE: Latch 'parallel query qref latch' Date: Thu, 14 Jun 2001 13:01:56 -0800 Ben: The qref latch is obtained for each Parallel Query process. It is acquired before the queue buffers can be manipulated so that communication can take place between the various slave processes. The latch is acquired for putting messages into the buffer. You will generally see lots of misses for this latch since it is acquired with a nowait option. Jon Walthour, OCDBA Oracle DBA Computer Horizons Cincinnati, Ohio --- Original Message --- From: Ben Jones [EMAIL PROTECTED] To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED] Date: 6/14/01 1:56:36 PM Does anyone know what causes waits on this latch ? Thanks Ben _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Ben Jones 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: Jon Walthour 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). _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Ben Jones 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: Latch 'parallel query qref latch'
Ben: As I said in my previous post, you may get a lot of waits on this latch and that is not necessarily something to be overly concerned about. However, you can lower this number by increasing the PARALLEL_MAX_SERVERS parameter. This is the maximum number of servers that are allowed to exist concurrently. Set the value to: (max # of concurrent PQO users) * (their max degree of parallelism) * 2 HTH! -- Jon Walthour, OCDBA Oracle DBA Computer Horizons Cincinnati, Ohio From: Ben Jones [EMAIL PROTECTED] Organization: Fat City Network Services, San Diego, California Reply-To: [EMAIL PROTECTED] Date: Fri, 15 Jun 2001 00:05:48 -0800 To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED] Subject: RE: Latch 'parallel query qref latch' Jon, Thanks for the email. My next question is fairly obvious...I'm getting a lot of waits on this latch (up to 5% of all waits) - how do I tune it ? (We've got a pretty typical environment here, a few big tables with parallel degree 4, on a 2 cpu box with 2G of RAM, and only a couple of end users doing big queries)... Any guidelines (from anybody) would be much appreciated... TIA Ben From: Jon Walthour [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED] Subject: RE: Latch 'parallel query qref latch' Date: Thu, 14 Jun 2001 13:01:56 -0800 Ben: The qref latch is obtained for each Parallel Query process. It is acquired before the queue buffers can be manipulated so that communication can take place between the various slave processes. The latch is acquired for putting messages into the buffer. You will generally see lots of misses for this latch since it is acquired with a nowait option. Jon Walthour, OCDBA Oracle DBA Computer Horizons Cincinnati, Ohio --- Original Message --- From: Ben Jones [EMAIL PROTECTED] To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED] Date: 6/14/01 1:56:36 PM Does anyone know what causes waits on this latch ? Thanks Ben _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Ben Jones 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: Jon Walthour 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). _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Ben Jones 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: Jon Walthour 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: Latch 'parallel query qref latch'
inter process communications between groups of parallel query server processes. often found in parallel == serial or parallel == parallel operations. -Original Message- Sent: Thursday, June 14, 2001 1:57 PM To: Multiple recipients of list ORACLE-L Does anyone know what causes waits on this latch ? Thanks Ben _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Ben Jones 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: Mohan, Ross 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).
