SQL Plan

SQL Plan

Provides the function to import the SQL execution plan as a string as a non-standard API. The SQL plan represents the sequence of actions Altibase performs to execute the statements. Option can be ON, OFF, or ONLY, and the default setting is OFF.

How to use

To get the SQL plan, before execution the SQL statement, the user must call the setExplainPlan(byteaExplainPlanMode) method of the AltibaseConnection object to specify what content to get the execution SQL plan. The aExplainPlanMode options that can be specified are described in the table below. After entering the SQL statement in the AltibaseStatement object, the execution plan of the string behavior can be returned by calling the getExplainPlan() method.

Function

Attribute	Attribute Value	Description
AltibaseConnection.EXPLAIN_PLAN_OFF	0	After executing the SELECT statement, the Plan Tree information is not displayed, only the result record is displayed
AltibaseConnection.EXPLAIN_PLAN_ON	1	After executing the SELECT statement, it shows the information of the Plan Tree along with the result record. In the plan tree, the number of records accessed, the amount of memory occupied by tuples, and the cost are displayed
AltibaseConnection.EXPLAIN_PLAN_ONLY	2	After executing the SELECT statement, it shows the information of the Plan Tree along with the result record. When EXPLAIN PLAN = ONLY, only the execution plan is generated without query execution, so items whose value is determined after actual execution, such as the ACCESS item, are displayed as question marks ("??")

Code Example

AltibaseConnection sConn = (AltibaseConnection)DriverManager.getConnection(sURL, sProps);
sConn.setExplainPlan(AltibaseConnection.EXPLAIN_PLAN_ONLY);
AltibaseStatement  sStmt = (AltibaseStatement)sConn.prepareStatement("SELECT sysdate FROM dual");
System.out.println(sStmt.getExplainPlan());

Code Result

------------------------------------------------------------
PROJECT ( COLUMN_COUNT: 1, TUPLE_SIZE: 8, COST: 0.01 )
 SCAN ( TABLE: DUAL, FULL SCAN, ACCESS: ??, COST: 0.01 )
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