- 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
- 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 .
- 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.
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