Hi there!
Do you know that Oracle Database could store blocks with different type of compression in the same segment? (unpartitioned table or partition/subpartition)
Simple example using Exadata.
Do you know that Oracle Database could store blocks with different type of compression in the same segment? (unpartitioned table or partition/subpartition)
Simple example using Exadata.
SQL*Plus: Release 11.2.0.2.0 Production on Sat Mar 19 17:37:41 2011 Copyright (c) 1982, 2010, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP, Data Mining and Real Application Testing options SQL> set linesize 500 SQL> create table vd.test_compress as select * from dba_objects; Table created. SQL> alter table vd.test_compress compress for OLTP; Table altered. SQL> insert /*+ APPEND */ into vd.test_compress select * from dba_objects; 647847 rows created. SQL> alter table vd.test_compress compress for QUERY LOW; Table altered. SQL> insert /*+ APPEND */ into vd.test_compress select * from dba_objects; 647850 rows created. SQL> alter table vd.test_compress compress for QUERY HIGH; Table altered. SQL> insert /*+ APPEND */ into vd.test_compress select * from dba_objects; 647848 rows created. SQL> alter table vd.test_compress compress for ARCHIVE LOW; Table altered. SQL> insert /*+ APPEND */ into vd.test_compress select * from dba_objects; 647847 rows created. SQL> alter table vd.test_compress compress for ARCHIVE HIGH; Table altered. SQL> insert /*+ APPEND */ into vd.test_compress select * from dba_objects; 647851 rows created. SQL> commit; Commit complete. SQL> select 2 case DBMS_COMPRESSION.GET_COMPRESSION_TYPE ('VD', 'TEST_COMPRESS', ROWID) 3 when 1 then '1 - No Compresson' 4 when 2 then '2 - OLTP' 5 when 4 then '4 - Query High' 6 when 8 then '3 - Query Low' 7 when 16 then '6 - Archive High' 8 when 32 then '5 - Archive Low' 9 END "Compression Type", 10 count( distinct DBMS_ROWID.ROWID_BLOCK_NUMBER (ROWID, 'SMALLFILE')) blocks 11 from vd.test_compress 12 group by DBMS_COMPRESSION.GET_COMPRESSION_TYPE ('VD', 'TEST_COMPRESS', ROWID) 13 order by 1; Compression Type BLOCKS ----------------- ---------- 1 - No Compresson 2653 2 - OLTP 700 3 - Query Low 232 4 - Query High 35 5 - Archive Low 35 6 - Archive High 21 6 rows selected.
1 комментарий:
Забавно. Не обращал внимание. Спасибо за input!
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