Commits
dimir authored 9ccba6f6b60
........S. [ZBX-6493] improve performance when working with Oracle by changing memory based prefetch to rows based Prefetching when working with Oracle is needed because otherwise it fetches only 1 row at a time when doing selects (default behavior). There are 2 ways to do prefetching: memory based and rows based. Based on the study optimal (speed-wise) memory based prefetch is 2 MB. But in case of many subsequent selects CPU usage jumps up to 100 %. Using rows prefetch with up to 200 rows does not affect CPU usage, it is the same as without prefetching at all. Before this fix: - 2 MB memory based prefetch was used with Oracle for selects - in case of big database housekeeper hits 100 % CPU usage After this fix: - 200 rows prefetch is used with Oracle for selects - in case of big database CPU usage is not affected by housekeeper More info: http://docs.oracle.com/cd/B28359_01/appdev.111/b28395/oci04sql.htm