Author: S J

Partitioned Primary Index (PPI) is an indexing mechanism that is useful in improving the performance of certain queries. When rows are inserted into a table, they are stored in an…

This chapter discusses the various JOIN strategies available in Teradata. Join Methods Teradata uses different join methods to perform join operations. Some of the commonly used Join methods are −…

A stored procedure contains a set of SQL statements and procedural statements. They may contain only procedural statements. The definition of stored procedure is stored in database and the parameters…

Macro is a set of SQL statements which are stored and executed by calling the Macro name. The definition of Macros is stored in Data Dictionary. Users only need EXEC…

Views are database objects that are built by the query. Views can be built using a single table or multiple tables by way of join. Their definition is stored permanently…

JOIN INDEX is a materialized view. Its definition is permanently stored and the data is updated whenever the base tables referred in the join index is updated. JOIN INDEX may…

A row is assigned to a particular AMP based on the primary index value. Teradata uses hashing algorithm to determine which AMP gets the row. Following is a high level…

EXPLAIN command returns the execution plan of parsing engine in English. It can be used with any SQL statement except on another EXPLAIN command. When a query is preceded with…

Compression is used to reduce the storage used by the tables. In Teradata, compression can compress up to 255 distinct values including NULL. Since the storage is reduced, Teradata can…

Teradata optimizer comes up with an execution strategy for every SQL query. This execution strategy is based on the statistics collected on the tables used within the SQL query. Statistics…