Recomendation when creating indexes in SAP HANA
- Avoid non-unique indexes
Columns in a column table are inherently index-like and therefore do not usually benefit from additional indexes. In some scenarios (for example, multiple-column joins or unique constraints), indexes can further improve performance.
Start without any indexes and then add them if needed.
- Create as few indexes as possible
Every index imposes an overhead in terms of space and performance, so you should create as few indexes as possible.
- Ensure that the indexes are as small as possible
Specify as few columns as possible in an index so that the space overhead is minimized.
- Prefer single-column indexes in the column store
Single-column indexes in the column store have a much lower space overhead because they are just light-weight data structures created on top of the column structure. Therefore, you should use single-column indexes whenever possible.
Due to the in-memory approach in SAP HANA environments, it is generally sufficient to define an index on only the most selective column. (In other relational databases, optimal performance can often only be achieved by using a multi-column index.)
Start without any indexes and then add them if needed.
Due to the in-memory approach in SAP HANA environments, it is generally sufficient to define an index on only the most selective column. (In other relational databases, optimal performance can often only be achieved by using a multi-column index.)
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