https://www.ibm.com/support/knowledgecenter/SSEPGG_10.5.0/com.ibm.db2.luw.apdv.embed.doc/doc/c0005563.html
Binding embedded SQL packages to a database
Binding is the process of creating a package from a bind file and storing it in a database.
Application, bind file, and package relationships
Database applications use packages for some of the same reasons that applications are compiled: improved performance and compactness. By precompiling an SQL statement, the statement is compiled into the package when the application is built, instead of at run time. Each statement is parsed, and a more efficiently interpreted operand string is stored in the package. At run time, the code generated by the precompiler calls run-time services database manager APIs with any variable information required for input or output data, and the information stored in the package is executed.
The advantages of precompilation apply only to static SQL statements. SQL statements that are executed dynamically (using PREPARE and EXECUTE or EXECUTE IMMEDIATE) are not precompiled; therefore, they must go through the entire set of processing steps at run time.
With the DB2® bind file description (db2bfd) utility, you can easily display the contents of a bind file to examine and verify the SQL statements within it. You can also display the precompile options used to create the bind file using the DB2 bind file description (db2bfd) utility. This can be useful in problem determination related to the bind file for your application.
You can set the STATICASDYNAMIC string on the GENERIC parameter of the BIND command to "yes" to instruct the DB2 database manager to store all statements in the catalogs and mark them as incremental bind. At run time, when the package is first loaded, the database manager uses the current session environment (rather than the package) to set up the section entries and other entities (text is populated and the package cache is accessed). Thereafter, the statements in the bound file behave the same as they would if you were using dynamic SQL. For example, sections will be implicitly recompiled for Database Definition Language invalidations, special register updates, and so on. The DB2 database manager provides this feature to facilitate the migration of embedded SQL C applications from other database systems.
-
Effect of DYNAMICRULES bind option on dynamic SQL
The PRECOMPILE command and BIND command
parameter DYNAMICRULES determines which rules
apply to dynamic SQL at run time. -
Using special registers to control the statement compilation environment
For dynamically prepared
statements, the special registers can be specified to define the statement
compilation environment. -
Package recreation using the BIND command and an existing bind file
Binding is the process
that creates the package the database
manager needs
to access the database when the application is executed. -
Rebinding existing packages with the REBIND command
Rebinding is the process
of recreating a package for an application program that was previously
bound. You must rebind packages if they were marked invalid or inoperative
or if the database statistics changed since the last binding. -
Bind considerations
If
your application uses a code page that differs from the database code
page, you must ensure that the code page used by the application is
compatible with the database code page during the bind process. -
Blocking considerations
When you want to turn blocking off for an embedded SQL
application and the source code is not available, the application
must be rebound using the BIND command and setting
the BLOCKING NO clause. -
Advantages of deferred binding
Precompiling with binding
enabled allows an application to access only the database used during
the precompile process. Precompiling with binding deferred, however,
allows an application to access many databases, because you can bind
the BIND file against each database. -
Performance improvements when using REOPT option of the BIND command
The bind option REOPT can significantly
improve the embedded SQL application performance.