What are indexes SAP

Indexes

•  Indexes are described as a copy of a database table reduced to specific fields. This data exists in sorted form. This sorting form eases fast access to the field of the tables. In order that other fields are also read, a pointer to the associated record of the actual table is included in the index. The indexes are activated along with the table and are created automatically with it in the database.

Creating Indexes  

Use

An index is a copy of a database table that is reduced to certain fields. This copy is always in sorted form. Sorting provides faster access to the data records of the table, for example, when using a binary search. A table has a primary index and a secondary index. The primary index consists of the key fields of the table and is automatically created in the database along with the table. You can also create further indexes on a table in the Java Dictionary. These are called secondary indexes. This is necessary if the table is frequently accessed in a way that does not take advantage of the primary index. Different indexes for the same table are distinguished from one another by a separate index name. The index name must be unique. Whether or not an index is used to access a particular table, is decided by the database system optimizer. This means that an index might improve performance only with certain database systems. You specify if the index should be used on certain database systems in the index definition. Indexes for a table are created when the table is created (provided that the table is not excluded for the database system in the index definition). If the index fields represent the primary keys of the table, that is, if they already uniquely identify each record of the table, the index is referred to as an unique index.

Prerequisites

You have opened a table for edit.

Procedure

...

       1.      Choose the Indexes tab.

       2.      To create an index, choose New.

       3.      Enter a name for the index. Index names, like table names, also have a prefix, followed by an underscore.

If the name of an index was registered on the name server, it cannot be deleted.

       4.      To select table fields, choose New. 

       5.      if the index is a unique index,

       6.      If the index is used for all databases, choose  and whether it is to be created for all databases. Choose the appropriate checkboxes. 

       7.      Choose File® Save All Metadata.

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