Hello,
I read that the compression is performed and optimized automatically in HANA during the delta merge process.
What confuses me is the documentation of the table "TABLE_COLUMNS" (TABLE_COLUMNS - SAP HANA SQL and System Views Reference - SAP Library). I found following text for column COMPRESSION_TYPE = "Type of compression: 'DEFAULT', 'PREFIXED', 'SPARSE', 'CLUSTERED', 'INDIRECT', 'RLE'. Columns in TABLE_COLUMNS show the default value which can be specified during table creation. They can also be updated using an 'ALTER TABLE' statement.”
This text indicates that I can select what type of compression is used manually, which does not fit to the self-managed optimization approach. I had a look in our SAP HANA and I could only find the values “DEFAULT” and “NONE” (which is not even listed here).
Is there a difference between “NONE” and “DEFAULT”? How is it set? (Probably it is just a piece of wrong documentation)
Thanks
Patrik