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Author's profile photo Rajarajeswari Kaliyaperuumal

How to perform manual Load and unload of column store tables in HANA

PLAYING AROUNG WITH COLUMN TABLES IN HANA USING SQLs:

Important tables which hold load status of column store table:M_CS_LOADS,M_CS_UNLOADS

As a continuation to my previous blog below, here are the screen prints as of how to load or unload a table manually inside HANA DB memory.

https://blogs.sap.com/2020/09/11/hana-column-store-load-and-unloads-and-sqls

Tables involved: M_CS_TABLES,M_CS_COLUMNS,M_CS_UNLOADS

1.Status check of SAPERP.BSEG inside HANA memory as on date.

Way 1:select * from m_cs_tables where table_name=’BSEG’ and schema_name = ‘SAPERP’

Below screen we can see that BSEG has 7 partitions and each partitions have 159 million records and all these partitions are partially loaded .

Way2:Using Studio

2.In above we see that this table is loaded partially. Now Lets find out which columns are loaded into memory for this table.

Way 1:select * from M_CS_COLUMNS where TABLE_NAME=’BSEG’ and SCHEMA_NAME=’SAPERP’

This shows the status of each column and its status in memory. LOADED = TRUE means that this column is inside memory

Way 2:Using Studio

Studio->Find table-BSEG-Columns Tab

3.Lets fully UNLOAD this table from memory

Now the table M_CS_TABLES and M_CS_COLUMNS would have got updated .

Studio ->Catalog->Find table – BSEG

Memory consumption in memory has become empty and loaded state has turned to NO

4.Lets fully check if our UNLOAD reason EXPLICIT has got recorded in M_CS_UNLOADS

Now we see that the unload reason for this table which we triggered manually has got recoded!1

5.Lets LOAD this table partially

When I say partially we can either load only 1 partition for this table out of 7 in our landscape or 11 column alone.

a.Only 1 column alone from this table

LOAD “SAPERP”.”BSEG”(BUKRS);

Now M_CS_COLUMNS table status have got updated as below.

1.Now lets load the table fully into memory

LOAD “SAPERP”.”BSEG” ALL;

In studio

 

Hope you understood how to manually load and unload tables in HANA DB!

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