Reduce disk space by compressing tables and fragments

You can reduce disk space by compressing data in tables and table fragments. After compressing data, you can repack the data to consolidate the free space in a table or fragment, and shrink the space for the data to return the free space to the dbspace.

Compression is advantageous for applications with a lot of I/O activity and for applications in which the reduction of disk space usage is critical. However, if your applications run with high buffer cache hit ratios and high performance is more important than space usage, you might not want to compress data, because compression might slightly decrease performance.

Compressing data, consolidating data, and returning free space have the following benefits:

Because compressed data covers fewer pages and has more rows per page than uncompressed data, the query optimizer might choose different plans after compression.

You can speed up compression and repacking by running the operations in parallel.


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