Data Compression
Question: where is a compressed table's compression dictionary stored, and can it be viewed/protected against failure? Answers: each dbspace holds its own compression repository (rsccompdict), so dictionaries are backed up along with the dbspace they belong to, and the sysmaster view syscompdicts_full exposes one row per compressed table/fragment (recovering a lost dictionary would need IBM support). The poster on 11.50.FC4 couldn't find that view; the cause was sysmaster not being updated during the FC3-to-FC4 upgrade, fixed by running $INFORMIXDIR/etc/conv/rebuildsmi.sh as user informix.
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Hi, When we compress any table, where we can find the Compression Dictionary ? Can it be viewed in any data dictionary ? As we need to make sure that Compression Dictionary is available, in case of any failure.
>Hi, >When we compress any table, where we can find the Compression Dictionary ? >Can it be viewed in any data dictionary ? >As we need to make sure that Compression Dictionary is available, in case of any failure. Each dbspace has it's own compression repository called rsccompdict, but there is a view in sysmaster called syscompdicts_full that should get you access to all the rsccompdict partitions for all dbspaces. That view has a byte field which should be the compression dictionary and there will be 1 row for each table/fragment that is compressed. I know you can unload that table to a file, but I haven't played around with trying to recover any lost compression dictionaries. I would think the best option should anything happen would be to have your unloaded data and then contact tech support to have them try to get your unloaded compression dictionary back in it's correct place. Jacques Renaut IBM IDS Advanced Support APD Team
Just to clarify one point. The tables/fragments which are stored in a dbspace? have their dictionaries stored in the same dbspace. So when you backup just a single dbspace the associated dictionaries are also backed up. John F. Miller III STSM, Support Architect miller3@us.ibm.com 503-578-5645 IBM Informix Dynamic Server (IDS) ids-bounces@iiug.org wrote on 06/24/2009 07:49:14 AM: > [image removed] > > Re: Data Compression [16152] > > Jacques Renaut > > to: > > ids > > 06/24/2009 07:50 AM > > Sent by: > > ids-bounces@iiug.org > > Please respond to ids > > >Hi, > >When we compress any table, where we can find the Compression Dictionary ? > >Can it be viewed in any data dictionary ? > >As we need to make sure that Compression Dictionary is available, in case of > any failure. > > Each dbspace has it's own compression repository called rsccompdict,but there > is a view in sysmaster called syscompdicts_full that should get you access to > all the rsccompdict partitions for all dbspaces. That view has a byte field > which should be the compression dictionary and there will be 1 row for each > table/fragment that is compressed. I know you can unload that table > to a file, > but I haven't played around with trying to recover any lost compression > dictionaries. I would think the best option should anything happen > would be to > have your unloaded data and then contact tech support to have them try to get > your unloaded compression dictionary back in it's correct place. > > Jacques Renaut > IBM IDS Advanced Support > APD Team > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. >
Hi, I am using 11.50.FC4 version. Here, i can't get the view named "syscompdicts_full" in sysmaster db. Is there anything else i have to do it to access this view. Regards Kasi
Hi, Here we had some troubles around sysmaster, but that´s because we upgraded from 11.50.FC3 to FC4. If that´s your case, also, you should rebuild your sysmaster, I think. I´ve being informed as below: --------------------------------------------- Unfortunately the sysmaster database does not get updated when upgrading from 11.50.FC3 to 11.50.FC4! So check with IBM on how to correct this or you can run the $INFORMIXDIR/etc/conv/rebuildsmi.sh script as user informix. Test this on your development server first, and do full backups; it should be safe and you shouldn't need to bounce the engine. ----------------------------------------------- Regards! Alexandre Marini Analista de Tecnologia da Informação - DBA SEFAZ-MS / UIMP / Sistemas: Fronteiras e SIG-DW SHAHZAD SALAM KASI escreveu: > Hi, > I am using 11.50.FC4 version. Here, i can't get the view named > "syscompdicts_full" in sysmaster db. Is there anything else i have to do it to > access this view. > > Regards > Kasi > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > > >
You can try rebuilding the sysmaster database. To do that as user informix run the following script $INFORMIXDIR/etc/conv/rebuildsmi.sh [or .badt on NT] John F. Miller III STSM, Support Architect miller3@us.ibm.com 503-578-5645 IBM Informix Dynamic Server (IDS) ids-bounces@iiug.org wrote on 06/25/2009 03:06:56 AM: > [image removed] > > Re: Data Compression [16156] > > SHAHZAD SALAM KASI > > to: > > ids > > 06/25/2009 03:07 AM > > Sent by: > > ids-bounces@iiug.org > > Please respond to ids > > Hi, > I am using 11.50.FC4 version. Here, i can't get the view named > "syscompdicts_full" in sysmaster db. Is there anything else i have > to do it to > access this view. > > Regards > Kasi > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. >