Now, I recently was performing some tracing on a query and got the statistic back CONSISTENT_GETS. Yeah, I know what that it... I thought... I actually thought it was reads from a ROLLBACK SEGMENT. i.e. a read needed to keep the data consistent in a query. After I made mods to the query... I started to doubt my understanding of it. Then I decided to go chasing it's REAL MEANING.... which seems to be a pretty hard thing to do. The following are definitions I have found.
* 'consistent changes' = changes made to block for CONSISTENT READ and changes made to SORT blocks
'consistent changes' = db_block_changes counts modifications made to CURRENT blocks
consistent gets - Number of times a consistent read was requested for a block.
consistent changes -
Number of times a user process has applied rollback entries to perform a consistent read on the block.
None of which are really clear about what they are trying to say.
So, I'm wondering if anyone can provide me with a hard definition once and for all, just so I can clear my understanding of where it is actually reading from.
Thanks,
OCP 8i, 9i DBA
Brisbane Australia