Rollback segment size refers to needing an accurate minimum number of bytes required by the rollback segment for any single given transaction or for the most important of these. There are differences between the kind of transactions (INSERTS,UPDATES and DELETES). For example the INSERTS generates less UNDO than deleting records because while rolling back an insert only requires deleting the row, rolling back a delete requires reinserting that row. It would take less bytes to store a rowid than to store information to reconstruct the actual row itself.

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Oracle 11g has a new hint telling data to persist in cache for x number of minutes. The syntax is:

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If a table or index becomes fragmented (not continuous on disk) performance can decrease. You can see which objects have over 10 extents with:

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A lot of developers use embedded SQL, or other tools to access their data. If a query is not optimized it can cause problems.

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In Oracle 11g we have the memory_max_target parameter which governs the total maximum RAM for both the PGA and SGA regions and the new memory_target parameter which governs the existing sizes. This allows RAM to be de-allocated from the SGA and transferred to the PGA.

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