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gc current block 2-way on select

in Database Administration (MOSC) 8 commentsAnswered

Hello all,

It's Oracle database 19.16 , 2 nodes RAC

We had an issue with bad execution plan due to some missing statistics. The problem though manifested itself by massive waits on "gc current block 2-way". After statistics gathering, the wait seems disappeared and replaced by "db file sequential read"

I don't understand, why a select statement generates massive requests for "current" table blocks. I checked based on the event parameters and requested blocks belongs to the table, not index, not header, not UNDO, temp... whatever, table blocks.

Again, the question is not why plan is bad or why we have massive number of requests, but why these table blocks are requested in current mode.

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