When one talks about "pinning" in indexes, what exactly is this? Is there some other word/term I can search for, as google has not provided any solutions.
It is part of a test question, where students were asked to define and describe pinning in relation to indexes.
Does anyone have an idea?
"pinning" in Oracle parlance basically means "ensure that this is always kept in memory".
It is frequently used for hot indexes that see a lot of queries against them, but might ordinarily age out of Oracle's cache (and thus have to be re-read from the disk). By pinning the index in memory the index scan will theoretically never require a disk access. If the index is large and the cache cycles frequently this could be a substantial performance improvement over frequently refreshing the cache.
