RE: Using PQ in FTS

Frits

> If mixed access (meaning both buffered and direct access)
> is done on objects where DML is happening, it can result
> in buffer busy waits because extents needs to be
> checkpointed before direct access can occure.

Be careful... checkpoints are not performed at extent level...

Up to 10gR1 checkpoints are executed at tablespace level.

As of 10gR2 checkpoints are executed at segment level (e.g. for a partitioned table a single partition can be checkpointed).

> Seen a great deal of buffer busy waits in 9.2.0.6/linux where
> concurrent DML queries got downgraded to serial due to the
> parallel automatic tuning.

Do you mean because of parallel adaptive multi user?

Regards,
Chris

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