Query Processing States

The SQL statement that references a UDF goes through query processing states in the SAP Sybase IQ server. In each of these states, the server uses the v4 API to communicate and negotiate with the UDF.

• Initial State
  Initial state on the server. The only UDF method called during the Initial state is _start_extfn.
• Annotation State
  During the annotation state the server updates the parse tree with the metadata necessary for efficient and correct query optimization.
• Query Optimization State
  During the Optimization state, the server is in the initial process of constructing a query plan. The server collects schema information and some preliminary statistical information.
• Plan Building State
  During the plan building state, the server builds the query execution plan based on the best plan found during the query optimization state.
• Execution State
  During the execution state, the server makes an execution call into the UDF.