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Function documentation Informix Database Storage Parameters in the ABAP Dictionary Locate the document in its SAP Library structure

Use

The Structure linkdatabase utility is the interface between the ABAP Dictionary and the relational database of the SAP System. You can use it to create, convert, and delete ABAP Dictionary objects, as well as database table, database views, and other SAP objects. You can do this online or in the background.

In a conversion, the definition of a table in the database is adapted to its changed definition in the ABAP Dictionary. You can also implement various analysis options, for example, to display table and index definitions, or check the consistency of objects.

For some SAP objects, particularly transparent tables, you can set user-specific database parameters, such as FRAGMENT BY EXPRESSION, FRAGMENT BY ROUNDROBIN, DBSPACE, EXTENT SIZE, NEXT SIZE, MINIMUM EXTENTS, MAXIMUM EXTENTS, LOCK MODE. You can also set flags to determine which parameters you want to apply the next time a table is created and which ones you want to take effect immediately. However, you cannot change all the values immediately. You can only change NEXT SIZE and LOCK MODE immediately (these values are valid if a new storage area is requested for the object).

Prerequisites

To use the database utility, you need an authorization for authorization object S_DDIC_OBJ, such as S_DDIC_ALL. Make sure that the authorizations in your system are set so that only the database administrator is authorized to configure the database parameters. Check the settings and change them if necessary.

Features

It only makes sense to fragment a table when you expect large amounts of data in the table. Do not fragment existing large tables with the database utility. Instead, stop the SAP System and do this manually with the database in "no logging" mode. For more information, see SAP Notes 79070, 83183, 81642, 83117.

Always fragment tables that you expect to exceed the following size limits:

You can fragment as follows:

This type of fragmentation places rows one after another in fragments, rotating through the series of fragments to distribute the rows evenly. We recommend you to use this fragmentation strategy due to the low administration involved. As a general rule, set up seven fragments.

This type of fragmentation puts rows that contain specified values in the same fragment. You specify a fragmentation expression that defines criteria for assigning a set of rows to each fragment, either as range rule or some arbitrary rule. The unique key index must contain the columns that are part of the expression criteria if the index is attached.

The advantage of fragmentation by expression is that fragments can be dropped and therefore allocated table space can be reused without reorganizing the table. Furthermore, query run times might improve when the optimizer chooses a query plan where, based on query restrictions, only specific fragments must be scanned.

For more information on the other parameters, see the Informix documentation.

Activities

For more information on how to call the database utility and set storage parameters, see:

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