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Enable Index To Search For NULLs By Adding Constant to Index List. But Some Constants Better Than Others (Never Let Me Down)

Submitted by Richard Foote on Thu, 2018-11-15 01:29

By default, Oracle doesn’t index an entry if all columns within the index are NULL. However, (as I’ve blogged previously), it’s possible to index all possible NULL values by simply adding a constant value to the index column list. Importantly, the CBO knows when a column has all it’s NULL values indexed and can potentially […]

Reuse Of Empty Index Leaf Blocks (Free Four)

Submitted by Richard Foote on Thu, 2013-08-01 08:50

A recent question by Stalin Subbiah has prompted me to write a quick post on the reuse of empty leaf blocks. In part, the question asked: “Is there anyway I could monitor the effectiveness of empty blocks being reused from freelist of an index resulting from purge process that we are planning to start soon?” […]

Index Block Dumps: Final Demo (Come Together)

Submitted by Richard Foote on Thu, 2010-11-04 11:21

The intent of this blog piece is just to bring together the whole discussion of block dumps and how we can use block dumps to demonstrate Oracle behaviour. First, let’s start with a fresh little demo, creating an index on a NAME column with 500 entries (note this specific demo uses an 11.2.0.1 database running [...]