Barry Lind wrote: > Oracle's implementation is a shared cache for all plans. This was > introduced in Oracle 6 or 7 (I don't remember which anymore). The net > effect was that in general there was a significant performance > improvement with the shared cache. However poorly written apps can now > bring the Oracle database to its knees because of the locking issues > associated with the shared cache. For example if the most frequently > run sql statements are coded poorly (i.e. they don't use bind variables, > eg. 'select bar from foo where foobar = $1' vs. 'select bar from foo > where foobar = || somevalue' (where somevalue is likely to be > different on every call)) the shared cache doesn't help and its overhead > becomes significant.
This is very interesting. We have always been concerned that shared cache invalidation could cause more of a performance problem that the shared cache gives benefit, and it sounds like you are saying exactly that. -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026 ---------------------------(end of broadcast)--------------------------- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])
