Data that you can compress

You can compress data in rows and simple large objects in dbspaces. However, you might not want to compress all the types of data that you can compress.

You can compress the following types of data:
  • The contents of data rows, including any remainder pieces for rows that span pages, and the images of those rows that are contained in logical log records.
  • Simple large objects (TEXT or BYTE data types) that are stored in dbspaces.

Table or table-fragment data with frequently repeating long patterns is very compressible. Certain types of data, such as text, might be more compressible than other types of data, such as numeric data, because data types like text might contain longer and more frequently repeating patterns.

I/O-bound tables, for example, tables that have bad cache hit ratios, are good candidates for compression. In OLTP environments, compressing I/O-bound tables can improve performance.

HCL Informix® can compress any combination of data types, because it treats all data to be compressed as unstructured sequences of bytes. Thus, the server can compress patterns that span columns, for example, in city, state, and zip code combinations. (The server uncompresses a sequence of bytes in the same sequence that existed before the data was compressed.)


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