& Lt; oracledatabase11gR2 performance adjustment and optimization & gt; & g

New Feature of 11g: advanced compression. You can specify the compression setting when createtable: nocompresscompress -- applicable to data warehouses. Enable compressfordirect_loadoperations only when inserting directly: Same as compressforalloperations -- applicable to oltp. All operations (including dml statements enable compression ).

New Feature of 11g: advanced compression. You can specify the compression setting when creating table: nocompress compress -- applicable to data warehouses. Enable compress for direct_load operations only when inserting directly: Same as compress for all operations -- applicable to oltp. All operations (including dml statements enable compression ).

New Feature of 11g: advanced compression.
You can specify the compression settings when creating table:
Nocompress
Compress -- applicable to data warehouses. Enable compression only when the direct path is inserted
Compress for direct_load operations: Same as above
Compress for all operations -- applicable to oltp. All operations (including dml statements enable compression ). In this case, the compatible parameter must be set to 11.1.0 or later.
Compress for oltp-applicable to oltp. All operations (including dml statements enable compression ). In this case, the compatible parameter must be set to 11.1.0 or later.

The compress for all operations syntax has been replaced in 11.2, but the compress for all operations still works.

It is worth noting that:

The advantage of compression is that

1. A full table scan can be completed with only a few physical block read operations.

2. the compressed data blocks allow more data to be stored in sga, which can potentially save high-speed buffer (db_cache_size)

Note: I personally understand that advanced compression does not play a major role in oltp, or it does not have any side effects.