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Deletes selectivity <percentage>%: <number_of> deletes, <number_of> rows read, <number_of> rows qualified

Updates selectivity <percentage>%: <number_of> updates, <number_of> rows read, <number_of> rows qualified


The ratio of read rows to modified rows is poor for UPDATE or DELETE statements.

Before UPDATE and DELETE statements can modify or delete rows, the rows must be located in the table. The same access strategies are used as in a SELECT statement.


User Response

Find the statement that causes this poor ratio of read rows to found rows, and check the access strategies for this statement.


For information on creating optimized SQL statements, see the SQL Optimizer documentation.


More Information

Relevant  DB-Analyzer Files
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DBAN_LOAD.csvAccesses and selectivity of SELECT, FETCH, INSERT, UPDATE, and DELETE statements
DBAN_RUNNING_COMMANDS.prt List of SQL statements that were active when starting Database Analyzer analysis. 
SAP Note
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Expert Sessions (Link to trainings)
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Session 16: SAP MaxDB SQL Query Optimization (Part 1)
Session 16: SAP MaxDB SQL Query Optimization (Part 2)

Find detailed information about different optimizer strategies and performance optimization.
Documentation (links)
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SQL Optimizer <übernommen>
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