Controls the use of file system buffering for IQ Temporary dbspaces.
ON, OFF
OFF
Can be set for the PUBLIC group only. You must shut down and restart the database for the change to take effect. DBA permissions are required to set this option.
Setting OS_FILE_CACHE_BUFFERING_TEMPDB to OFF prevents file system buffering for IQ Temporary Store files. Turning off file system buffering saves a data copy from the file system buffer cache to the main IQ buffer cache. Usually this reduces paging caused by competition for memory between the IQ buffer manager and the file system buffer of the operating system. When OS_FILE_CACHE_BUFFERING_TEMPDB reduces paging, this option improves performance; however, if the IQ page size for the database is less than the block size of the file system (typically only in testing situations), performance decreases, especially during multiuser operation.
Experiment with this option to determine the best setting for different conditions. You must restart the database for the new setting to take effect.
This direct I/O performance option is available on Sun Solaris UFS, Linux, Linux IBM, AIX, and Windows file systems only. This option has no effect on HP-UX and HP-UXi and does not affect databases on raw disk. In Linux, direct I/O is supported in kernel versions 2.6.x.
To enable direct I/O on Linux kernel version 2.6 and AIX, also set the environment variable IQ_USE_DIRECTIO to 1. Direct I/O is disabled by default in Linux kernel version 2.6 and AIX. IQ_USE_DIRECTIO has no effect on Sun Solaris and Windows.
Sybase IQ does not support direct I/O on Linux
kernel version 2.4. If you set the IQ_USE_DIRECTIO
environment variable on Linux kernel version 2.4, the Sybase IQ server
does not start. The error Error: Invalid Block I/O
argument, maybe <pathname> is a directory,
or it exceeds maximum file size limit for the platform, or trying
to use Direct IO on unsupported OS is reported.
OS_FILE_CACHE_BUFFERING controls file system buffering for IQ Main Store files.
“OS_FILE_CACHE_BUFFERING option”
Chapter 4, “Managing System Resources” in the Performance and Tuning Guide
