Sap Hana - Table

About

Table data structure in the context of SAP HANA.

Dummy

The dual table is called the dummy table.

select 1 from dummy;

Type

It is possible to change an existing table from one storage type to the other (ALTER TABLE ALTER TYPE).

History

  • only insert (no update)
  • select as of …

Row vs Column

Storage Table Size Update Type
Column-based Big Bulk
Row-based small Frequent single

Column store

  • Calculations are typically executed on individual or a small number of columns.
  • The table is searched based on the values of a few columns.
  • The table has a large number of columns.
  • The table has a large number of rows and columnar operations are required (aggregate, scan, and so on)
  • High compression rates can be achieved because the majority of the columns contain only a few distinct values (compared to the number of rows).

Row store

  • The application needs to process only one single record at one time (many selects and /or updates of single records).
  • The application typically needs to access the complete record.
  • The columns contain mainly distinct values so compression rate would be low.
  • Neither aggregations nor fast searching are required.
  • The table has a small number of rows (for example, configuration tables).

Virtual

Management

Memory (Load|Unload)

  • LOAD <table_name>
  • UNLOAD <table_name>

System view

Truncate

Rename

rename table oldTableName to  newTableName

RENAME TABLE

Create

Sizing

Documentation / Reference


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