Understanding the Logical Log Usage

Am using version 10.00.UC7X1 and have a few *basic* questions on the usage of the logical log file. The database has a logging mode of unbuffered logging with a page size is 2048 bytes (as returned by onstat -b). I have 3 log files with each file being 5000 KB in size. I have a table with the following definition: sizetbl (i lvarchar(255), j lvarchar(3000), k lvarchar(255), m lvarchar(2500)); I observe that for an insert of a single row, one page is used in the logical log (based on onstat -l). The insert just inserts single characters: insert into sizetbl values ('1','2','3','4'); 1. Why does one page get used in the logical log for each insert? onstat -l displays parameters called numrecs and numpages. Thedocumentation says: numrecs: Is the number of records written; numpages: Is the number of pages written For the above operation, I observe that for each insert the numrecs gets incremented by three whereas the numpages gets incremented by 1. What does the term "records" mean in this context? 2. onlog displays a length of 44 (for begin) + 64 (for hinsert) + 40 (for commit) for a transaction involving a single insert. What does this length mean? The length of the logical record in bytes? Thanks a lot in advance!

On May 27, 7:05 am, Krishna <calvinkri...@gmail.com> wrote: > Am using version 10.00.UC7X1 and have a few *basic* questions on the > usage of the logical log file. > The database has a logging mode of unbuffered logging with a page size > is 2048 bytes (as returned by onstat -b). I have 3 log files with each > file being 5000 KB in size. > > I have a table with the following definition: > sizetbl (i lvarchar(255), j lvarchar(3000), k lvarchar(255), m > lvarchar(2500)); > > I observe that for an insert of a single row, one page is used in the > logical log (based on onstat -l). The insert just inserts single > characters: > > insert into sizetbl values ('1','2','3','4');> > 1. Why does one page get used in the logical log for each insert? > onstat -l displays parameters called numrecs and numpages. The> documentation says: numrecs: Is the number of records written; > numpages: Is the number of pages written The key to the answer of this question is the fact that you are using unbuffered logging. So that as soon as a commit work is hit, it forces the logical log buffer to be flushed to disk. When this occurs, it will only use the portion of a page that is needed, so you will possibly end up with non-full logical log pages. > > For the above operation, I observe that for each insert the numrecs > gets incremented by three whereas the numpages gets incremented by 1. > What does the term "records" mean in this context? Logical log records. As you mention below, you have 3 log records, 1 for the begin, 1 for the hinsert and 1 for the commit. > > 2. onlog displays a length of 44 (for begin) + 64 (for hinsert) + 40 > (for commit) for a transaction involving a single insert. What does > this length mean? The length of the logical record in bytes? Yes > > Thanks a lot in advance!