Strategy

The database system can generally use various different strategies (search strategies) to access data. Among other things, these search strategies differ in the costs that they incur when executed.

Search Strategies of SQL Optimizer
Search Strategy
CATALOG KEY ACCESS
CATALOG SCAN
CATALOG SCAN USING USER EQUAL CONDITION
DIFFERENT STRATEGIES FOR OR-TERMS
EQUAL CONDITION FOR INDEX
EQUAL CONDITION FOR KEY
IN CONDITION FOR INDEX
IN CONDITION FOR KEY
INDEX SCAN
JOIN VIA INDEXED COLUMN
JOIN VIA KEY COLUMN
JOIN VIA KEY RANGE
JOIN VIA MULTIPLE INDEXED COLUMNS
JOIN VIA MULTIPLE KEY COLUMNS
JOIN VIA RANGE OF MULTIPLE INDEXED COLUMNS
JOIN VIA RANGE OF MULTIPLE KEY COLUMNS
NO RESULT SET POSSIBLE
NO STRATEGY NOW (ONLY AT EXECUTION TIME)
RANGE CONDITION FOR KEY
RANGE CONDITION FOR INDEX
SUBQ CONDITION FOR INDEX
SUBQ CONDITION FOR KEY
TABLE SCAN

More Information

Concepts of the Database System

Search Strategies
List of All Search Strategies

Database Studio, Analyzing SQL Statements (EXPLAIN)