You Asked Dear Tom

Is 11.2.0.2 compression better than 10.2.0.4 ? if so how ?

Thanks
C
and we said...In Oracle 9iR2 and later, with enterprise edition, you have what is known as 'basic compression' as a feature in the database. Basic compression works at the block level, removing redundant bits of information on a database block into the block header and storing them once per block - not once per occurrence on the block. This allows us to store 2x, 3x, 4x or more data per block. It only works during direct path operations such as insert /*+APPEND*/, alter table t move, create table as select, sqlldr direct=y. It does not PREVENT you from using normal insert/update/delete statements - it just means that the results of those statements will result in some non-compressed data. A single table may have some blocks compressed and some blocks not compressed - that works fine. There are restrictions as to what you can do with a basic compressed table as far as dropping columns and the like.

In Oracle 11g Release 1 and above there is the new advanced compression option. This option allows for normal, conventional path operations to be compressed - so a transactional application may save it's data in a compressed format without using direct path operations. It also removes most of the restrictions associated with basic compression such as a 255 column limit on compressed tables, scheema modifications, and the like.

So, the original basic compression still exists in 11g for enterprise edition users, and there is the new advanced compression that works in many more cases.

Is it "better"? It is the same sort of compression - it just works in more situations with fewer restrictions - so in that sense, yes it is "better"
原文：http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:2852001100346111839