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An index is a copy of a database table that is reduced to certain fields. Different indexes for the same table are distinguished from one another by a separate index name. The index name must be unique.

Prerequisites

You have:

  • Created a table

  • Opened the table for editing

Context

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. There are two types of indexes:

  • Primary

    The primary index consists of the key fields of the table and is automatically created in the database along with the table.

  • Secondary

    You can also create further indexes on a table in 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.

Procedure

  1. Choose the Indexes tab.
  2. To create an index, choose the Add an Index to the Database Table pushbutton.

    The New Index dialog opens.

  3. Specify the index name by filling the Prefix and Suffix fields.
    Note

    Once registered on the name server, the index name cannot be deleted.

  4. Choose Finish .

    The index appears in the list of the Indexes tab.

  5. Expand the index node.
  6. Add table fields to the index.

    1. In the context menu of Fields , choose Add/Edit Index Fields .

      The Edit Fields dialog opens.

    2. Select the table fields that you want to add to the index, then choose Finish .

    3. To change the order of fields in the index, select a field and choose Up or Down in the context menu.

    4. To remove a field from the index, select the field and choose Remove Index Fields in the context menu.

  7. To specify if the index should be used on a certain database, expand the Properties subtree.

    • The Included Databases subtree lists all databases that the index is used on. To exclude the index on a database, select the database and choose Do Not Create on Database in the context menu.

      The database is moved under the Excluded Databases node.

    • The Excluded Databases subtree lists all databases that the index is not used on. To use the index on a database, select the database and choose Create on Database in the context menu.

      The database is moved under the Included Databases node.

  8. (Optional) Specify database specific parameters for the index.

    For more information, see Specifying Database-Specific Parameters .

  9. To specify if the index is unique or not, select Unique and choose Toggle Unique Index in the context menu.
  10. To save your data, choose Save .

Next Steps

Creating Tables