Is dirty read enough ?

Posted in 2003

Topics: Stored Procedures & SPL, Transactions, Locking & Isolation, Clustering, Grid & MACH11

↪ replying to xiaofeng chen

ar — Mon, 23 Jun 2003 14:38:17 +0200 — source: Usenet: comp.databases.informix

With set isolation to dirty read, clients will be able to select rows on a table, even if there are updates or inserts in progress. IDS doesn't try to put a shared lock on the rows it reads. I think set isolation to dirty read is enough. Regards "xiaofeng chen" <xchen@boco.com.cn> a 'crit dans le message de news:bd6nch$sb4$1@terabinaries.xmission.com... > > This is a multi-part message in MIME format. > > ------=_NextPart_000_007B_01C339B8.442F6BB0 > Content-Type: text/plain; > charset="us-ascii" > Content-Transfer-Encoding: 7bit > > Hi, everyone , > > Here I encounter a problem, in our system some tables were accessed > by many clients at the same time. In order to increase > concurrence and prevent influence with each other, we add "set lock mode > to wait" and "set isolation to dirty read" in our client code, > and in server side, we change the lock mode from page to row for the > tables , fragments the tables for distributing read/write operations, > add detached indexs instead of non-detached for tables. > But, I still wonder if it's enough, can it prevent system locks for > the index/table which will affect our clients? > If IDS wants to adjust the indexes according to data insertion, does it > affect the whole table?, and if it dose, how long will it take ? > > > Any comments are appreciated. > Michael. > > > ------=_NextPart_000_007B_01C339B8.442F6BB0 > Content-Type: text/html; > charset="us-ascii" > Content-Transfer-Encoding: quoted-printable > > <html xmlns:o=3D"urn:schemas-microsoft-com:office:office" = > xmlns:w=3D"urn:schemas-microsoft-com:office:word" = > xmlns=3D"http://www.w3.org/TR/REC-html40">; > > <head> > <META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; = > charset=3Dus-ascii"> > > > <meta name=3DProgId content=3DWord.Document> > <meta name=3DGenerator content=3D"Microsoft Word 10"> > <meta name=3DOriginator content=3D"Microsoft Word 10"> > <link rel=3DFile-List href=3D"cid:filelist.xml@01C339B6.E70E21C0"> >  > <style> >  > </style> >  > </head> > > <body lang=3DZH-CN link=3Dblue vlink=3Dpurple = > style=3D'tab-interval:21.0pt;text-justify-trim: > punctuation'> > > <div class=3DSection1 style=3D'layout-grid:15.6pt'> > > style=3D'font-size: > 9.0pt;mso-bidi-font-size:10.0pt;font-family:Arial'>Hi, class=3DGramE>everyone > , <o:p></o:p> > > style=3D'font-size: > 9.0pt;mso-bidi-font-size:10.0pt;font-family:Arial'><o:p> </o:p></spa= > n> > > style=3D'font-size: > 9.0pt;mso-bidi-font-size:10.0pt;font-family:Arial'> style=3D'mso-spacerun:yes'>   Here I encounter a = > problem, in our > system some tables were accessed by many clients at the same time. In = > order to increase<o:p></o:p> > > face=3DArial> style=3D'font-size:9.0pt;mso-bidi-font-size:10.0pt;font-family:Arial'>con= > currence size=3D1 face=3DArial> style=3D'font-size:9.0pt;mso-bidi-font-size: > 10.0pt;font-family:Arial'> and prevent influence with each other, we add = > “set > lock mode to wait” and “set isolation to dirty read” = > in our > client code, <o:p

xiaofeng chen — Mon, 23 Jun 2003 18:50:02 -0700 — source: Usenet: comp.databases.informix

This is a multi-part message in MIME format. ------=_NextPart_000_007B_01C339B8.442F6BB0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi, everyone , Here I encounter a problem, in our system some tables were accessed by many clients at the same time. In order to increase concurrence and prevent influence with each other, we add "set lock mode to wait" and "set isolation to dirty read" in our client code, and in server side, we change the lock mode from page to row for the tables , fragments the tables for distributing read/write operations, add detached indexs instead of non-detached for tables. But, I still wonder if it's enough, can it prevent system locks for the index/table which will affect our clients? If IDS wants to adjust the indexes according to data insertion, does it affect the whole table?, and if it dose, how long will it take ? Any comments are appreciated. Michael. ------=_NextPart_000_007B_01C339B8.442F6BB0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable <html xmlns:o=3D"urn:schemas-microsoft-com:office:office" = xmlns:w=3D"urn:schemas-microsoft-com:office:word" = xmlns=3D"http://www.w3.org/TR/REC-html40">; <head> <META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; = charset=3Dus-ascii"> <meta name=3DProgId content=3DWord.Document> <meta name=3DGenerator content=3D"Microsoft Word 10"> <meta name=3DOriginator content=3D"Microsoft Word 10"> <link rel=3DFile-List href=3D"cid:filelist.xml@01C339B6.E70E21C0">  <style>  </style>  </head> <body lang=3DZH-CN link=3Dblue vlink=3Dpurple = style=3D'tab-interval:21.0pt;text-justify-trim: punctuation'> <div class=3DSection1 style=3D'layout-grid:15.6pt'> Hi, everyone , <o:p></o:p> <o:p> </o:p></spa= n>    Here I encounter a = problem, in our system some tables were accessed by many clients at the same time. In = order to increase<o:p></o:p> con= currence and prevent influence with each other, we add = “set lock mode to wait” and “set isolation to dirty read” = in our client code, <o:p></o:p> and= in server side, we change the lock mode from = page to row for the tables , fragments the tables for distributing read/write operations,<o:p></o:p> add=@@N

Is dirty read enough ?

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