Wednesday, December 28, 2011

Oracle Advanced Compression

Oracle Advanced Compression and Oracle Database 11g Release 2 helps manage more data in a cost-effective manner. With data volumes, on average, tripling every two years, Oracle Advanced Compression delivers compression rates of 2-4x across all types of data and savings from compression will cascade throughout the data center, reducing network traffic and data backups as well. And by reading fewer blocks off disk, Oracle Advanced Compression also improves query performance.

Oracle Advanced Compression is an option of the Oracle 11g database (separately licensed) that allows data in the database to be compressed. Oracle Advanced Compression offers the following advantages:

1.) OLTP Compression  : It allows structured and unstructured data to be compressed on insert,update and delete  operations.The following are features : 
  • New compression algorithm uses deferred or batched approach
  • Data is inserted as is without compression until  PCTFREE  value is reached.
  • Compression of data starts once PCTFREE threshold is reached
  • Can be enabled at  table, partition or tablespace level
  • No need of decompressing the data during reads
  • Recommended for low update activity tables

2.) Data Pump Compression   : In Data Pump, the compression of metadata was introduced in 10g and compression of "data" was introduced in 11g.This covers the following features : 
  • Both are Inline operation
  • Save on storage allocation
  • No need to uncompress before Import
  • Implemented with COMPRESSION attribute, Values supported are ALL, DATA_ONLY, METADATA_ONLY . 

Data guard Compression : It includes the following features : 
  • Redo is compressed as it is transmitted over a network .
  • Helps efficiently utilize network bandwidth when data guard  is across data centers
  • Faster re-synchronization of Data guard  during gap resolution.
  • Recommended for low network bandwidth .
  • Implemented with attribute “COMPRESSION”  of initialization parameter log_archive_dest_n

.4.) RMAN Backup Compression  It compresses the RMAN backups.The followinf features are
  • Supports compression of backups using "ZLIB"  algorithm .
  • Faster compression and low CPU utilization compared to default BZIP2 (10g) .
  • Low compression ratio  compared to BZIP2 .
  • Implement  with  CONFIGURE COMPRESSION ALGORITHM  ‘value’ command where value can be High , Medium(ZLIB) and Low(LZO) .

The Oracle Database 11g Advanced Compression option introduces a comprehensive set of compression capabilities to help customers maximize resource utilization and reduce costs. It allows IT administrators to significantly reduce their overall database storage footprint by enabling compression for all types of data – be it relational (table), unstructured (file), or backup data . Although storage cost savings are often seen as the most tangible benefit of compression, innovative technologies included in the Advanced Compression Option are designed to reduce resource requirements and technology costs for all components of our IT infrastructure, including memory and network bandwidth .

The benefits of compression are manyfold
1.) Reduction of disk space used for storage .
2.) Reduction in I/O bandwidth requirements .
3.) Faster full table scans .
4.) Lower server memory usage.

Enjoy    J J J

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