Create table as select from all_obje… select segment_name, segment_type, bytes/1024/1024 MB from user_segments where segment_type='TABLE' and segment_name='DV_XXXXXX_HST'; --- 4341 (Size in MB before COMPRESSION) Then we compressed the table for OLTP using. Basic and Advanced compression are installed by default without the need of explicitly selecting the component for install during the installation of the Oracle Database Server, or creation of the database. See more about this at, http://docs.oracle.com/cd/E11882_01/appdev.112/e18294/adlob_smart.htm#ADLOB45960, Compression Effectiveness and Performance, TEST #2: Query performing a full table scan, TEST #3: Query repeated 1,000,000 times reading single rows by rowid in random order, TEST #4: Update all rows setting a non-redundant column to the same value, TEST #5: Update all rows setting a redundant column to a new value not present prior to the update. For more details see Document 1459216.1. ALTER TABLE sales MERGE PARTITIONS sales_q1_1998, sales_q2_1998 INTO PARTITION sales_1_1998 TABLESPACE ts_arch_1_1998 COMPRESS FOR OLTP UPDATE INDEXES; For more details and examples for partition management operations, refer to Partition Administration . Connor and Chris don't just spend all day on AskTOM. Oracle Database attempts to compress data during direct-path INSERT operations when it is productive to do so. If a table contains LOB columns then it is possible to compress table only without compressing the LOB data. You can also catch regular content via Connor's blog and Chris's blog. NOTE: Currently Advanced Compression cannot be disabled. Or if video is more your thing, check out Connor's latest video and Chris's latest video from their Youtube channels. OLTP Table Compression, therefore, extends the benefits of compression to all application workloads. This document is focused solely on OLTP Compression which is one of several types of heap segment compression (HSC), the other features of the Advanced Compression Option as listed above are not covered here. OLTP compression differs from basic compression found in prior versions as it allows compression during DML operations and not just during direct path loads. ALTER TABLE DV_XXXXXX_HST MOVE COMPRESS FOR OLTP; checking the size of the table after compression. ” Oracle’s OLTP Table Compression uses a unique compression algorithm specifically designed to work with OLTP application. Compressed blocks contain a structure called a symbol table that maintains compression metadata. When a table is set to use OLTP compression and rows are inserted into a new block in that table they are inserted uncompressed, just as with a non-compressed table. The strategies I used in the original article were: 1. This form of compression is recommended for OLTP environments. Share and learn SQL and PL/SQL; free access to the latest version of Oracle Database! Expertise through exercise! * When you enable table compression by specifying either COMPRESS or COMPRESS BASIC, you enable basic table compression. Basic compression comes with oracle 11g Enterprise Edition, To make table as OLTP compressed its again extra cost option with … In the above explanation can you mention why was the blocks space not got released even though the table is compressed what could be done to release the blocks, Is this answer out of date? All subsequent (aka normal) DML will not create compressed data. The algorithm works by eliminating duplicate values within a database block, even across multiple columns. * When you enable table compression by specifying COMPRESS FOR OLTP, you enable OLTP table compression. As it is important to share common terminology for this topic an excerpt from the manual is provided below for clarity. Note that Hybrid Columnar Compression has specific requirements for underlying storage including Exadata, ZFS, or Pillar. Compressing securefile columns have different syntax, syntax that specifiles compression within the LOB clause. Compress = compress data *only* during direct mode operations (sqlldr, ctas, insert-append, alter table move). If it is, please let us know via a Review. Enhancement has been logged to request the possibility to disable/un-install the option. As the name implies, this option enables compression for all operations, including regular DML statements. OLTP Table Compression reduces the associated compression overhead of write operations making it suitable for transactional or OLTP environments as well.
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