Re: Not using Physical Log, why?

Can you describe the sequence of events?... Was the table already loaded, or did you load it before the update? Was there any other operation on the table? How did you check that no physical log was used? On Sun, Dec 5, 2010 at 12:05 AM, Cesar Inacio Martins < cesar_inacio_martins@yahoo.com.br> wrote: > Hi , > > I already identify this situation on v11.10 xC1 and since then I not > found any answer. > I just forgot about this and today the situation "popup" and again I not > found the reason.... > > v11.70 UC1DE - OpenSuse 11.2 > > This is a very simple test environment. > - Database with log > - 1 table with +- 520.000 records , rowsize 1320, 1 PK > - update executed over 1 field ( NCHAR(100) ), single transaction (begin > work) , changing 100.000 records > - No physical log is used > - Only logical log is filled > > If the transaction is rolled back, then the physical log is used.. > appear to be filled by the recover from logical log, and monitoring with > onstat -D , I can see the pages writes on the physical log and the> dbspace used by table grow up with exactly same values... > > Looking the Logical Log content (onlog -n # -l ) they used HUPDAT > record, what have the before/after image. > I already looking into the manual about this situation and not found. > Can someone explain why the engine choose this way ? > > Regards > Cesar > > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > The table already existed or you created and loaded it just before the update? -- Fernando Nunes Portugal http://informix-technology.blogspot.com My email works... but I don't check it frequently... --0015174c0c72d7b1b404969fb0a4

Hi Fernando, Please, read my other reply for details how I executed the test. There is no other event occurring , only my session. Yes, the table already loaded (few days ago). No, any other operation... On 12/04/2010 11:28 PM, Fernando Nunes wrote: > Can you describe the sequence of events?... Was the table already loaded, or > did you load it before the update? > Was there any other operation on the table? > How did you check that no physical log was used? > > On Sun, Dec 5, 2010 at 12:05 AM, Cesar Inacio Martins< > cesar_inacio_martins@yahoo.com.br> wrote: > >> Hi , >> >> I already identify this situation on v11.10 xC1 and since then I not >> found any answer. >> I just forgot about this and today the situation "popup" and again I not >> found the reason.... >> >> v11.70 UC1DE - OpenSuse 11.2 >> >> This is a very simple test environment. >> - Database with log >> - 1 table with +- 520.000 records , rowsize 1320, 1 PK >> - update executed over 1 field ( NCHAR(100) ), single transaction (begin >> work) , changing 100.000 records >> - No physical log is used >> - Only logical log is filled >> >> If the transaction is rolled back, then the physical log is used.. >> appear to be filled by the recover from logical log, and monitoring with >> onstat -D , I can see the pages writes on the physical log and the>> dbspace used by table grow up with exactly same values... >> >> Looking the Logical Log content (onlog -n # -l ) they used HUPDAT >> record, what have the before/after image. >> I already looking into the manual about this situation and not found. >> Can someone explain why the engine choose this way ? >> >> Regards >> Cesar >> >> >> >> > ******************************************************************************* >> Forum Note: Use "Reply" to post a response in the discussion forum. >> >> > The table already existed or you created and loaded it just before the > update? >

I can't give you a definitive answer, but I believe this has to do with what Jacques Renaut mentioned in another reply. In version 10- we had fuzzy checkpoints... Which meant that pages changed by "fuzzy" operations were not written to disk at checkpoint. We changed that, but on the "fuzzy" stuff explanation in the manual it's also written that fuzzy operations did not force physical log. So although we eliminated fuzzy checkpoints some of the optimizations created at the time are probably still used. Regards. On Sun, Dec 5, 2010 at 2:07 AM, Cesar Inacio Martins < cesar_inacio_martins@yahoo.com.br> wrote: > Hi Fernando, > > Please, read my other reply for details how I executed the test. > > There is no other event occurring , only my session. > Yes, the table already loaded (few days ago). > No, any other operation... > > On 12/04/2010 11:28 PM, Fernando Nunes wrote: > > Can you describe the sequence of events?... Was the table already loaded, > or > > did you load it before the update? > > Was there any other operation on the table? > > How did you check that no physical log was used? > > > > On Sun, Dec 5, 2010 at 12:05 AM, Cesar Inacio Martins< > > cesar_inacio_martins@yahoo.com.br> wrote: > > > >> Hi , > >> > >> I already identify this situation on v11.10 xC1 and since then I not > >> found any answer. > >> I just forgot about this and today the situation "popup" and again I not > >> found the reason.... > >> > >> v11.70 UC1DE - OpenSuse 11.2 > >> > >> This is a very simple test environment. > >> - Database with log > >> - 1 table with +- 520.000 records , rowsize 1320, 1 PK > >> - update executed over 1 field ( NCHAR(100) ), single transaction (begin > >> work) , changing 100.000 records > >> - No physical log is used > >> - Only logical log is filled > >> > >> If the transaction is rolled back, then the physical log is used.. > >> appear to be filled by the recover from logical log, and monitoring with > >> onstat -D , I can see the pages writes on the physical log and the> >> dbspace used by table grow up with exactly same values... > >> > >> Looking the Logical Log content (onlog -n # -l ) they used HUPDAT > >> record, what have the before/after image. > >> I already looking into the manual about this situation and not found. > >> Can someone explain why the engine choose this way ? > >> > >> Regards > >> Cesar > >> > >> > >> > >> > > > > ******************************************************************************* > >> Forum Note: Use "Reply" to post a response in the discussion forum. > >> > >> > > The table already existed or you created and loaded it just before the > > update? > > > > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > -- Fernando Nunes Portugal http://informix-technology.blogspot.com My email works... but I don't check it frequently... --0015174bef24b74ba20496b428ae