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Index Rebuild

How to rebuild a 12 TB index that you accidentally dropped from a 55 TB table

Once upon a time there was a very experienced database administrator who accidentally dropped a 12 TB index from a 55 TB table. The question I had was “How did he fix it?”(read more)

Index Advanced Compression: Multi-Column Index Part II (Blow Out)

I previously discussed how Index Advanced Compression can automatically determine not only the correct number of columns to compress, but also the correct number of columns to compress within specific leaf blocks of the index. However, this doesn’t mean we can just order the columns within the index without due consideration from a “compression” perspective. As […]

Index Advanced Compression: Multi-Column Index Part I (There There)

I’ve discussed Index Advanced Compression here a number of times previously. It’s the really cool additional capability introduced to the Advanced Compression Option with, that not only makes compressing indexes a much easier exercise but also enables indexes to be compressed more effectively than previously possible. Thought I might look at a multi-column index to highlight just […]

Index Rebuild, the Need vs the Implications Support Note 989093.1 (Getting Better)

Once upon a time, Oracle Support had a note called Script: Lists All Indexes that Benefit from a Rebuild (Doc ID 122008.1) which lets just say I didn’t view in a particularly positive light :) Mainly because it gave dubious advice which included that indexes should be rebuilt if: Deleted entries represent 20% or more of […]

Index Rebuild – Does it use the Index or the Table ? (Nothing Touches Me)

A common question that gets asked is does Oracle access the index itself or the parent table during an index rebuild to extract the necessary data for the index ? Thought it might be worth a blog post to discuss. Now if the index is currently in an UNUSABLE state, then Oracle clearly can’t use the existing [...]

Rebuilding Indexes and the Clustering Factor Solution (Move On)

Excellent !! This quiz created quite a bit of debate and it was nice to sit back and read some interesting discussions. The Clustering Factor is basically the measurement of how well aligned the data in the underlining table is in relation to the index and is the number of table related I/Os required to read the entire table via a [...]

Rebuilding Indexes and the Clustering Factor Quiz (One Of The Few)

Today’s question has been prompted by various recent comments regarding the Clustering Factor (CF) of an index and how to change the CF requires a reorg of the underlining table. It used to be quite a common myth that if the CF of an index was greater that “X” or based on some nonsensical formula the [...]