Re: partition buffer summary - Btree percentage

I believe it is fixed in 7.31UC3 and 7.30UC7, I relocated my desk and cannot find the note on the subject so I'm going from memory here. I do not think there is a fix contemplated for 7.2x so upgrades MAY have to rebuild indexes to eliminate the problem. Art S. Kagel "Carlson@WHSmith" wrote: > > Any idea in which version this bug is fixed? > > John Carlson > Informix DBA > WHSmith USA > > plsmith@my-deja.com wrote: > > > > Vardan > > > > You have almost certainly run into bug no. 115327 and you should be > > able to request a patch to fix it. > > It is a bug in 7.2x and 7.3x whereby btree pages can be generated with > > an invalid page type. This page type is then handled incorrectly by the > > new 7.30 buffer priority management. > > Dropping and rebuilding affected indexes is a reasonable workaround, but > > the problme could re-occur depending on the habits of you application. > > The invalid page types are generated when all the rows are deleted from > > a table thus compressing the index down to a single page. When rows are > > inserted an invalid page type is then copied through all the leaf nodes. > > If you look at onstat -R you will see that the majority of pages are in > > the medium-high category, whereas data pages are medium-low. Leaf node > > pages should also be medium low, but because of the invalid page type > > they are placed in the medium-high category, thus squeezing out the data > > pages. If you install a patch you should see a reversal of these > > percentages and an increase in your read cache. > > If you talk to Informix tech support refer them to case No. 861366 which > > contains a reproducable example. > > I have a small script which will identify invalid pages types (sql > > courtesy of John Miller, thanks ). > > > > email me if you would like a copy. > > > > hth > > Pete Smith > > Logica > > > > In article <7s5n3g$mq7$1@nnrp1.deja.com>, > > Vardan Aroustamian <vaar@geocities.com> wrote: > > > Hello, > > > > > > I'm new to SAP environment and would like to get some input > > > from experienced users. > > > > > > Anyone knows of some "usual" percentage for Data vs. Btree > > > pages in the buffer pool (from onstat -P output). > > > > > > Currently I have > > > > > > Percentages: > > > Data 20.09 > > > Btree 77.75 > > > Other 2.16 > > > > > > I heard about some bug when Btree is more than 90%. > > > I'm not sure will I reach that number. > > > > > > Informix 7.30.UC7XB > > > SunOS 5.5.1 > > > > > > Database ~50GB > > > SAP 4.5 > > > > > > Actually I believe this is not SAP specific question. > > > Anyway, thanks for any information. > > > > > > Vardan > > > > > > -- > > > Vardan Aroustamian > > > vaar@geocities.com > > > > > > Sent via Deja.com http://www.deja.com/ > > > Share what you know. Learn what you don't. > > > > > > > Sent via Deja.com http://www.deja.com/ > > Share what you know. Learn what you don't.

It is sorta fixed in 7.30UC7 --- we are using version 7.30UC7XK1, and it seems to be okay there (at least our small test system didn't show the buffer problem). Will probably be stressing it this week as we upgrade SAP.... Doug Art S. Kagel wrote in message <37E7BA3B.DC191AA1@bloomberg.net>... >I believe it is fixed in 7.31UC3 and 7.30UC7, I relocated my desk and >cannot find the note on the subject so I'm going from memory here. I do >not think there is a fix contemplated for 7.2x so upgrades MAY have to >rebuild indexes to eliminate the problem. > >Art S. Kagel > >"Carlson@WHSmith" wrote: >> >> Any idea in which version this bug is fixed? >> >> John Carlson >> Informix DBA >> WHSmith USA >> >> plsmith@my-deja.com wrote: >> > >> > Vardan >> > >> > You have almost certainly run into bug no. 115327 and you should be >> > able to request a patch to fix it. >> > It is a bug in 7.2x and 7.3x whereby btree pages can be generated with >> > an invalid page type. This page type is then handled incorrectly by the >> > new 7.30 buffer priority management. >> > Dropping and rebuilding affected indexes is a reasonable workaround, but >> > the problme could re-occur depending on the habits of you application. >> > The invalid page types are generated when all the rows are deleted from >> > a table thus compressing the index down to a single page. When rows are >> > inserted an invalid page type is then copied through all the leaf nodes. >> > If you look at onstat -R you will see that the majority of pages are in >> > the medium-high category, whereas data pages are medium-low. Leaf node >> > pages should also be medium low, but because of the invalid page type >> > they are placed in the medium-high category, thus squeezing out the data >> > pages. If you install a patch you should see a reversal of these >> > percentages and an increase in your read cache. >> > If you talk to Informix tech support refer them to case No. 861366 which >> > contains a reproducable example. >> > I have a small script which will identify invalid pages types (sql >> > courtesy of John Miller, thanks ). >> > >> > email me if you would like a copy. >> > >> > hth >> > Pete Smith >> > Logica >> > >> > In article <7s5n3g$mq7$1@nnrp1.deja.com>, >> > Vardan Aroustamian <vaar@geocities.com> wrote: >> > > Hello, >> > > >> > > I'm new to SAP environment and would like to get some input >> > > from experienced users. >> > > >> > > Anyone knows of some "usual" percentage for Data vs. Btree >> > > pages in the buffer pool (from onstat -P output). >> > > >> > > Currently I have >> > > >> > > Percentages: >> > > Data 20.09 >> > > Btree 77.75 >> > > Other 2.16 >> > > >> > > I heard about some bug when Btree is more than 90%. >> > > I'm not sure will I reach that number. >> > > >> > > Informix 7.30.UC7XB >> > > SunOS 5.5.1 >> > > >> > > Database ~50GB >> > > SAP 4.5 >> > > >> > > Actually I believe this is not SAP specific question. >> > > Anyway, thanks for any information. >> > > >> > > Vardan >> > > >> > > -- >> > > Vardan Aroustamian >> > > vaar@geocities.com >> > > >> > > Sent via Deja.com http://www.deja.com/ >> > > Share what you know. Learn what you don't. >> > > >> > >> > Sent via Deja.com http://www.deja.com/ >> > Share what you know. Learn what you don't.