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Direct path and buffered reads again: compressed tables.

In the previous post on the decision between buffered and direct path reads I showed the decision is depended on the version. Up to and including version the size of a segment needs to be five times small table threshold in order to be considered for direct path reads, and starting from the database starts considering direct path reads starting from small table threshold. The lower limit just discussed is small table threshold or five times small table threshold with lower versions, upper limit is called “very large object threshold” (VLOT) and is five times the size of the buffercache, which is the threshold after which a table scan always is going via direct path.