Extending POSTGRESQL Using C

 Although POSTGRESQL offers a large number of functions, operators, data types, and aggregates, sometimes users may still need to create their own. Chapter  showed how to create functions in languages other than C. This chapter covers C functions and the creation of custom operators, data types, and aggregates that behave just like the ones already present in POSTGRESQL.

Extending POSTGRESQL in this way involves several steps:

1.

Write C code to implement the new functionality.

2.

Compile the C code into an object file that contains CPU instructions.

3.

Issue CREATE FUNCTION  commands to register the new functions.

4.

Issue the proper commands if creating operators, data types, or aggregates:

• CREATE OPERATOR
• CREATE TYPE 
• CREATE AGGREGATE 

The full details of extending POSTGRESQL are beyond the scope of this book. This chapter will therefore provide just an overview of this topic. The Programmer's Manual mentioned in Appendix  has more detailed information.

 

• Write the C Code
• Compile the C Code
• Register the New Functions
• Create Operators, Types, and Aggregates
• Summary