Data Base Optimizer part two

Posted by Isha | 10:24 AM

Continued from the last post data base optimizer part one.

Unsuitable access path :

If the single object analysis establishes that an expensive SQL statement has an unsuitable access path, you can narrow (and thus optimize) the search.

The search range is the number of data records that needs to be checked in a table in order to satisfy an SQL statement. When the SQL statement is processed on the database, the search range is dynamically determined by the WHERE clause, the database index used, and the access strategy selected.

You can narrow the search by:

Solving technical problems

Changing the ABAP coding

Changing the index design


Suitable access path:

If the single object analysis establishes that the SQL statement analyzed has a suitable access path, you can optimize it by:

Reducing the rows to be transferred

Reducing the columns to be transferred

Reducing data transfer

Avoiding unnecessary SQL statements

You can reduce the number of rows to be transferred, for example, by optimizing the WHERE clause or by using aggregate functions.

You can reduce the number of columns to be transferred, for example, by formulating a suitable field list or, in the case of database changes, by using UPDATE .. SET field = value.

You can reduce data transfer between database server and application server by formulating your SQL statements in such a way that data is transferred in as large blocks as possible (a full fetch is 32 KB). You can do this by avoiding nested SELECT statements, for example.

Unnecessary SQL statements are either similar or identical SQL statements. Similar SQL statements can often be grouped together. Identical SQL statements can be avoided by buffering data either in an internal table in the program or on the application server.

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