Quick Answer: What Is Cardinality In SAP HANA?

What is temporal join in SAP HANA?

A temporal join lets you set time intervals for which you want to fetch records.

It indicates the time interval mapping between the master data and the transaction data..

WHY IS LEFT JOIN faster than inner?

I’ve experienced some cases where a left join has been faster than a inner join. The underlying reason is this: If you have two tables and you join on a column with an index (on both tables). … If the optimizer chooses to optimize the left join in the order it is written it will perform better than the inner join.

What is referential join?

Referential Join is a join between two tables, which ensures that referential integrity is always maintained between the tables in question. Any record on the left will have a corresponding record on the right if the table on the right is taken into consideration.

What is the use of cardinality in SAP HANA?

The cardinality setting is used by the optimizer to decide, based on the fields requested in the query, whether a join needs to be executed or whether it can be omitted without comprising the correctness of the data.

What is join cardinality?

The cardinality of a join between two tables is the numerical relationship between rows of one table and rows in the other. Common cardinalities include one-to-one, one-to-many, and many-to-many. For example, consider a database of electronic health records.

What is join pruning in Hana?

Join pruning is a process where SAP HANA eliminates both tables and joins from its execution plan based how the joins are defined in the information view and how data is queried from the information view.

Which join is faster in Hana?

Third, INNER JOIN will give you better performance compare to LEFT JOIN or LEFT OUTER JOIN. Another thing about JOINs and performance, you better use them on PRIMARY KEYS and not on each column. For me, both the time join with multiple fields is performing faster than join with concatenated fields.

What is star join in Hana?

Star joins connect a central data entity to multiple entities that are logically related. You can create a graphical calculation view with star joins that join multiple dimensions to a single fact table.

What is Information View in SAP HANA?

SAP HANA Modelling is an activity by which we create information view. Information View is similar to dimension, cube or information provider of BW. This information view is used for creating the multi-dimensional data model.

What is cardinality SAP?

Cardinality (SAP Library – BC – ABAP Dictionary) Privacy Policy | Powered by: Cardinality. The cardinality (n:m) describes the foreign key relationship with regard to the number of possible dependent records (records of the foreign key table) or referenced records (records of the check table).

What is dynamic join in SAP HANA?

Dynamic joins are special type of joins. In this join type, two or more fields from two data sources are joined using a join condition that changes dynamically based on the fields requested by the client. For example –Table1 and Table2 are joined on Field1 and Field2.

What is referential join in SAP HANA?

Referential joins in SAP HANA are used whenever there is a primary key and foreign key association between two tables. And, referential integrity is when for every value in the foreign key column, there is a reference value in the primary key column of the master data table.

How does Hana views improve performance?

Always follow – HANA Development PointsUse left outer joins maximum.Specify cardinality in joins (n:1 or 1:1) – only if sure.Set optimize join = true (only if cardinality is set like above)Use table functions instead of scripted calculation views.Execute in SQL-engine (for HANA live)More items…•