Internal Operations

This section describes the underlying steps that SAP Sybase IQ performs on remote servers on behalf of client applications.

• Query Parsing
  When a statement is received from a client, the database server parses it. The database server raises an error if the statement is not a valid SQL Anywhere SQL statement.
• Query Normalization
  In query normalization, referenced objects are verified and data type compatibility is checked.
• Query preprocessing
  Query preprocessing prepares the query for optimization. It may change the representation of a statement so that the SQL statement that SAP Sybase IQ generates for passing to a remote server is syntactically different from the original statement, even though it is semantically equivalent.
• Complete passthrough of the statement
  For efficiency, SAP Sybase IQ passes off as much of the statement as possible to the remote server. Often, this is the complete statement originally given to SAP Sybase IQ.
• Partial passthrough of the statement
  If a statement contains references to multiple servers, or uses SQL features not supported by a remote server, the query is decomposed into simpler parts.