Subject | RE: [firebird-support] Correct Page Size for the database. |
---|---|
Author | Leyne, Sean |
Post date | 2006-08-23T22:33:43Z |
Martin,
situations.
I would suggest that you review your application and the SELECT
statements which it is executing. This is where I think would find the
source of any performance problems.
As to your question, there are 3 factors which I believe need to be
considered in setting the page size value:
1 - the Depth value from GStat (db statistics) for indexes. A value of
3 or more suggests that a larger page size is required.
2 - the size of the data rows and/or the size of BLOBs to be stored. If
you are going to be storing large BLOB; the bigger the page, the better,
since this will reduce the number of fetchs the engine will need to
perform.
3 - To a lesser extent, the size of the disk cluster (or is it sector
size?) for the drive you are using. In an ideal world, I would format
the drive so that the db page size and the cluster size would be the
same. Having a db page size which is larger than a disk page could mean
that the disk would need to perform multiple disk reads in order to read
a single db page. The growing prevalence of cache disk controller and
SAN based disks, is reducing the significance of drive characteristics
as factor to selection of database page size.
Sean
> Currently using 4096 and wondering if we should be using somethingelse
> to improve performance.Performance is only affected by database page size in exceptional
situations.
I would suggest that you review your application and the SELECT
statements which it is executing. This is where I think would find the
source of any performance problems.
As to your question, there are 3 factors which I believe need to be
considered in setting the page size value:
1 - the Depth value from GStat (db statistics) for indexes. A value of
3 or more suggests that a larger page size is required.
2 - the size of the data rows and/or the size of BLOBs to be stored. If
you are going to be storing large BLOB; the bigger the page, the better,
since this will reduce the number of fetchs the engine will need to
perform.
3 - To a lesser extent, the size of the disk cluster (or is it sector
size?) for the drive you are using. In an ideal world, I would format
the drive so that the db page size and the cluster size would be the
same. Having a db page size which is larger than a disk page could mean
that the disk would need to perform multiple disk reads in order to read
a single db page. The growing prevalence of cache disk controller and
SAN based disks, is reducing the significance of drive characteristics
as factor to selection of database page size.
Sean