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Concatenated Indexes

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 12.1.0.2, 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 […]

Concatenated Bitmap Indexes Part II (Everybody’s Got To Learn Sometime)

A basic little post to conclude this discussion. The issues regarding whether to go for single column indexes vs. concatenated indexes are similar for Bitmap indexes as they are for B-Tree indexes.   It’s generally more efficient to access a concatenated index as it’s only the one index with less processing and less throwaway rowids/rows [...]

Concatenated Bitmap Indexes Part I (Two Of Us)

Although Bitmap Indexes are commonly created on one column, you can create multi-column, concatenated Bitmap indexes as well.   Many of the same issues and factors in deciding to create a single, multi-column index vs. several, single column indexes apply to Bitmap indexes as they do with B-Tree indexes, although there are a number of [...]