How to trigger compression optimization manually?

[Former Member]

Hi Expert,

I did hard merge in my column table, and I checked out table M_DELTA_MERGE_STATISTICS and find there is no compression optimization recorded.

Hence I think there is compression optimization happened after manual delta merge(hard or forced), so could you please tell me how to trigger compression optimization manually via hana studio or sql statment?

Regards.

Jian Wu

[lucas_oliveira]

Hello Jian,

As the FAQ Note on compression optimization clearly describes:

"[...]

Be aware that hard and forced merges don't trigger a compression optimization. Use hard and forced merges as rarely as possible. If these merge types have to be used, consider a manual compression optimization afterwards:

UPDATE "<table_name>" WITH PARAMETERS ('OPTIMIZE_COMPRESSION' = 'YES')

[...]"

Always good to check if the table auto_optimize_compression is set to 'ON'. You can check all disabled auto compress by using HANA_Tables_ColumnStore_AutoCompressionDisabled query from 1969700 - SQL statement collection for SAP HANA.

BRs,

Lucas de Oliveira

[radim_sykora]

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