There are several improvements to compression in IBM® Informix® version 12.10. See the What's new in Informix page in the information center for links to documentation on these features. Here's a summary:
Improve space utilization by compressing, repacking, and shrinking B-tree indexes
You can use SQL administration API commands or CREATE INDEX statements to save disk space by compressing B-tree indexes. You can also use SQL administration API commands to consolidate free space in a B-tree index, return this free space to the dbspace, and estimate the amount of space that is saved by compressing the indexes.
Save disk space by compressing simple large objects in dbspaces
You can use SQL administration API commands to save disk space by compressing simple large objects (TEXT and BYTE data types) that are stored in the same partition in the same dbspace as the table in which they are referenced. When you run an SQL administration API compress or uncompress command, the database server compresses both the table row data and the referenced simple large objects. You can choose to compress or uncompress only the table row data or only the referenced simple large objects.
Save disk space by enabling automatic data compression
You can use the COMPRESSED keyword with the CREATE TABLE statement to enable the automatic compression of large amounts of in-row data when the data is loaded into a table or table fragment. Then, when 2,000 or more rows of data are loaded, the database server automatically creates a compression dictionary and compresses the new data rows that are inserted into the table.
Also, when you run SQL administration API create dictionary and compress commands on existing tables and fragments, you enable the automatic compression of subsequent data loads that contain 2,000 or more rows of data. If you run an uncompress command, you disable automatic compression.
In addition to saving space, automatic compression saves time because you do not have to compress the data after you load it.
Manage compression in IBM OpenAdmin Tool (OAT) for Informix
has new compression options on the Space Administration
> Tables and Indexes
You can enable automatic compression when you compress existing tables and fragments. You disable automatic compression when you uncompress a table or fragment.
You can compress indexes. You can consolidate free space in indexes (repack) and return free space to the dbspace (shrink). You can also estimate the amount of space that you can save if you compress an index. An index must have at least 2000 keys to be compressed.
You can compress simple large objects (TEXT and BYTE data types) when you compress tables and fragments. You can also estimate the amount of space that you can save if you compress simple large objects.
IBM Informix Schema Manager Plug-in for OpenAdmin Tool (OAT)
has the following compression options on the SQL ToolBox
> Schema Manager
You can enable automatic compression of row data when you create a table. The database server automatically creates a compression dictionary and compresses the data when 2000 or more rows of data are loaded into the table or fragment.
You can compress an index when you create an index that has at least 2000 keys.