SAP suite on HANA - indexes

[Former Member]

Hi,

I have a general query that when we go for ERP over HANA, does the tables i.e., which are conventional tables in row database ( write optimized DB)

will have as usual primary index and secondary indexes defined or how it is handled in HANA DB.

Without primary/unique index there may be an issue in handling the duplicate records / values in the conventional databases.

Please forward me the link where it explains the handling of indexes on tables in HANA.

Thanks & Regards,

DVRK

[vivekbhoj · Accepted solution]

Hi Rama,

In SAP HANA, the table is generally stored in column store,

In this a column is divided into two parts - Dictionary Encoding and Attribute Vector.

Dictionary Encoding stores Implicit value ID and unique records only.

Then Attribute Vector stores position of all the records and corresponding Implicit Values.

Thus there is no duplicacy and no need of indexes.

To have more understanding and clearer picture, please watch these videos:

https://open.sap.com/course/hana-warmup

Here everything is explained about Column Store, Insertion and Deletion in column store table.

Regards,
Vivek

[Former Member · Accepted solution]

Hi Vivek,

As read from documentation the SAP HANA is a hybrid database where it has the row type

storage which is write optimized and column type which is read optimized.

My query is that when the table or data is written to the row type, can it have indexes ?

please correct if am wrong in my understanding.

BR,

Ramakrishna

[yeushengteo · Accepted solution]

Hi Ramakrishna,

You can still have index on row table in HANA.

Row table can be seen from system table m_rs_tables and row table index from system table m_rs_indexes.

Regards.

YS

[vivekbhoj · Accepted solution]

Hi Rama.

Yeah, If you are using Row Store, you will still have primary indexes.

You can still create secondary indexes.

http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/70d16119-ad21-2e10-de8b-eaaedf86b...

As Yeu Sheng mentioned above, you can check those two system tables in  _SYS_STATISTICS schema.

You can check this SQL reference regarding Tables and indexes:

http://help.sap.com/hana/html/sql_create_table.html