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Oracle Option: Advanced Compression

Oracle Advanced Compression complements Enterprise Edition basic table compression feature with comprehensive data compression and Information Lifecycle Management capabilities, including those specifically tailored to Oracle's engineered systems, like Oracle Exadata.

Oracle advanced compression promises to

reduce the cost of data storage
improve performance

Compression algorithm

Database block level (Advanced Row Compression?)

The compression algorithm replaces duplicate values within a database block with a refernce to a symbol table in the same block which contains the actual (duplicated) value.

The benefit of storing the symbol table in the same database block is that no IO costs are involved when resolving a reference.

This strategy is assumes that OLTPs and datawarehouse applications have lot of duplicate values in a database block.

Features

Advanced Row Compression	Used for structured data
Advanced LOB Deduplication and Compression	Used for unstructered data
Advanced Index Compression
RMAN and Data Pump compression	Database backups
Advanced Network Compression	Compression of data transferred between database and application.
Data Guard redo log transport Compression	Network

Heat maps

A heat map records data modification times at row and segment level and access time at segment level.

These statics can then be used to automaticaly compress and move data base using the declarative language of automatic data optimization (ADO).

Compress existing tables

Existing table can be compress with

dbms_redefinition
alter table … move row store compress advanced
alter table … row store compress advanced (only data of future DML is compressed)

Estimating compression ratios

Before compressing existing tables, it might be worthwile to estimate their compression ratio with dbms_compression (also referred to as compression advisor).

Flashback Data Archives

Advanced Compression also optimizes storage requirements for history tables in Flashback Data Archives when using them to track transactional changes.

Links

Oracle Advanced Compression FAQ

Index

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