how to free up memory in sap hana
DESCRIPTION
How to free up memory in HANA? Is it possible to unload Table from memory? - Yes, it is possible. SAP HANA Appliance can be used in smarter way to achieve maximum out of it. In a typical business scenario, one SAP HANA appliance is used for DEV, TRN, TST environments. So, definitely there will be a major issue in this case – How to handle memory as memory is limited in that particular HANA appliance? Under normal circumstances, the SAP HANA database manages the loading and unloading of tables into and from memory independently. Actually, the main aim of SAP HANA database is to keep all relevant data in memory. But, one can manually load and unload individual tables if necessary. How?....It’s simple, and it can be done from SAP HANA Studio itself. Select the table by right click and choose the option “Unload …” And later, manually load the table into memory again, if needed. Moreover, if somebody fires the query associated to the same unloaded table, SAP HANA will pick & load the same table into memory FULL or PARTIALLY, purely depending upon the executed query. Again, if one needs to free up memory, he/she can manually trigger the delta merge operation for a column table manually in SAP HANA Studio. The delta merge operation is related to the memory management concept of the column store, i.e, the part of the SAP HANA Database that manages data organized in columns in memory. So, options are as follows: “Unload …” – Free up memory by unloading table from memory “Load …” – Loading the table into memory “Merge…” – Triggering delta merge operation for a column tableTRANSCRIPT
How to free-up the Memory in SAP HANA? Prepared by Debajit Banerjee
http://debajitb.wix.com/debajitbanerjee | http://debajitb.wix.com/debajitbanerjee/apps/blog 1
Under normal circumstances, the SAP HANA database manages the loading and unloading of tables into and
from memory independently. Actually, the main aim of SAP HANA database is to keep all relevant data in memory.
But, one can manually load and unload individual tables if necessary. How?
....It’s simple, and it can be done from HANA Studio itself.
Select the table by right click and choose the option “Unload …”
And later, manually load the table into memory again, if needed.
Moreover, if somebody fires the query associated to the same unloaded table, SAP HANA will pick & load the same table
into memory FULL or PARTIALLY, purely depending upon the executed query.
Again, if one needs to free up memory, he/she can manually trigger the delta merge operation for a column table
manually in SAP HANA Studio. The delta merge operation is related to the memory management concept of the column
store, i.e., the part of the SAP HANA Database that manages data organized in columns in memory.
So, options are as follows:
“Unload …” – Free up memory by unloading table from memory
“Load …” – Loading the table into memory
“Merge…” – Triggering delta merge operation for a column table
Here are the screenshots for clear understanding of table unloading from and loading into memory:
In this example, we will unload a table, EKKN from memory and then reloaded into memory.
How to free-up the Memory in SAP HANA? Prepared by Debajit Banerjee
http://debajitb.wix.com/debajitbanerjee | http://debajitb.wix.com/debajitbanerjee/apps/blog 2
How to free-up the Memory in SAP HANA? Prepared by Debajit Banerjee
http://debajitb.wix.com/debajitbanerjee | http://debajitb.wix.com/debajitbanerjee/apps/blog 3
It actually triggers the equivalent statement ‘SELECT TOP 1000 * FROM “schema_name”.”table_name”’ at the backend.
So, here is the result.
And this triggers the change in the memory also. The same table has been PARTIALLY loaded into memory.
How to free-up the Memory in SAP HANA? Prepared by Debajit Banerjee
http://debajitb.wix.com/debajitbanerjee | http://debajitb.wix.com/debajitbanerjee/apps/blog 4
Later, the corresponding table has been FULLY loaded into Memory.
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