Feb 26, 2020Unlike both Basic and Advanced Row Compression, Oracle's Hybrid Columnar Compression technology utilizes a combination of both row and columnar
Oracle Advanced Compression provides three levels of RMAN Backup Compression: Low, Medium, and High. The amount of storage savings increases from Low to High, and typically uses fewer CPU resources than RMAN Basic Compression.
Oracle's Hybrid Columnar Compression (HCC) technology is a method for organizing data within a set of database blocks. HCC utilizes a combination of both row and columnar methods for storing data. A logical construct, called the Compression Unit (CU), stores a set of HCC-compressed data.
How does Oracle Database compress data?
By using a compression algorithm specifically designed for relational data, Oracle Database can compress data effectively and in such a way that Oracle Database incurs virtually no performance penalty for SQL queries accessing compressed tables.
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It’S Compression, Jim, But Not as We Know it.
The rest of the questions I’ve asked above can best be addressed by seeing how Oracle does compression, and the answer is that (for basic and OLTP compression) Oracle doesn’t really do compression.
What it does is “de-duplication” at the block level.
Imagine you had three rows in a block containing the following data: Oracle could notice that the v.
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When Does (Basic) Compression Work
The usual questions people ask about compression are: “how do I create compressed data?”, “how does Oracle decompress the blocks?”, “what impact does compression have on performance?” and the question you should ask before using any feature “are there any side effects I need to worry about?” The easiest way to answer the first question is through a.
Basic and Standard Compression. With standard compression Oracle Database compresses data by eliminating duplicate values in a database block. Standard compression only works for direct path operations (CTAS or IAS). If the data is modified using any kind of conventional DML operation (for example updates), the data within that database block is uncompressed to make the modifications and is written back to disk uncompressed.
Oracle Advanced Compression provides database-compression capabilities that improve performance while reducing storage costs. Oracle Advanced Compression reduces an organization’s overall database storage footprint for all types of data—relational (table), unstructured (file), index, Data Guard redo, network, and RMAN backups—and also improves performance for all components of the database infrastructure, including memory and...
The rest of the questions I’ve asked above can best be addressed by seeing how Oracle does compression, and the answer is that (for basic and OLTP compression)
Oracle doesn’t really do compression. What it does is “de-duplication” at the block level.
Compression can be performed on several partitions or a complete partitioned heap-organized table. You can do this compression by either defining a complete partitioned table as being compressed, or by defining it on a per-partition level.
Table compression was introduced in Oracle 9i as a space saving feature for data warehousing projects. In 11g it is now considered a mainstream feature that is acceptable for OLTP databases. In addition to saving storage space, compression can result in increased I/O performance and reduced memory use in the buffer cache.
