postgresql

History

Tom Lane ea4686e3e1 Implement CREATE/DROP OPERATOR CLASS. Work still remains: need more documentation (xindex.sgml should be rewritten), need to teach pg_dump about it, need to update contrib modules that currently build pg_opclass entries by hand. Original patch by Bill Studenmund, grammar adjustments and general update for 7.3 by Tom Lane.		2002-07-29 22:14:11 +00:00
..
Makefile	Fix relative path references so that make knowns which dependencies refer	2000-08-31 16:12:35 +00:00
README	Postgres95 1.01 Distribution - Virgin Sources	1996-07-09 06:22:35 +00:00
copyfuncs.c	Implement CREATE/DROP OPERATOR CLASS. Work still remains: need more	2002-07-29 22:14:11 +00:00
equalfuncs.c	Implement CREATE/DROP OPERATOR CLASS. Work still remains: need more	2002-07-29 22:14:11 +00:00
list.c	Update copyright to 2002.	2002-06-20 20:29:54 +00:00
makefuncs.c	Update copyright to 2002.	2002-06-20 20:29:54 +00:00
nodeFuncs.c	Update copyright to 2002.	2002-06-20 20:29:54 +00:00
nodes.c	Update copyright to 2002.	2002-06-20 20:29:54 +00:00
outfuncs.c	Back out BETWEEN node patch, was causing initdb failure.	2002-07-18 17:14:20 +00:00
print.c	Update copyright to 2002.	2002-06-20 20:29:54 +00:00
read.c	Update copyright to 2002.	2002-06-20 20:29:54 +00:00
readfuncs.c	Back out BETWEEN node patch, was causing initdb failure.	2002-07-18 17:14:20 +00:00

README

*******************************************************************************
*                                                                             *
* EXPLANATION OF THE NODE STRUCTURES                                          *
*    - Andrew Yu (11/94)                                                      *
*                                                                             *
* Copyright (c) 1994, Regents of the University of California                 *
*                                                                             *
* $Id: README,v 1.1.1.1 1996/07/09 06:21:32 scrappy Exp $
*                                                                             *
*******************************************************************************

INTRODUCTION

The current node structures are plain old C structures. "Inheritance" is
achieved by convention. No additional functions will be generated. Functions
that manipulate node structures reside in this directory.


FILES IN THIS DIRECTORY

    Node manipulation functions:
	copyfuncs.c	- copying a node
	equalfuncs.c	- comparing a node
	outfuncs.c	- convert a node to ascii representation
	readfuncs.c	- convert ascii representation back to a node
	makefuncs.c	- creator functions for primitive nodes

    Node definitions:
	nodes.h		- define node tags (NodeTag)
	pg_list.h	- generic list 
	primnodes.h	- primitive nodes
	parsenodes.h	- parse tree nodes
	plannodes.h	- plan tree nodes
	relation.h	- inner plan tree nodes
	execnodes.h	- executor nodes
	memnodes.h	- memory nodes


STEPS TO ADD A NODE

Suppose you wana define a node Foo:

1. add a tag (T_Foo) to the enum NodeTag in nodes.h (You may have to
   recompile the whole tree after doing this.)
2. add the structure definition to the appropriate ???nodes.h file. If you
   intend to inherit from, say a Plan node, put Plan as the first field of
   you definition.
3. if you intend to use copyObject, equal, nodeToString or stringToNode,
   add an appropriate function to copyfuncs.c, equalfuncs.c, outfuncs.c
   and readfuncs.c accordingly. (Except for frequently used nodes, don't
   bother writing a creator function in makefuncs.c)


HISTORICAL NOTE

Prior to the current simple C structure definitions, the Node structures 
uses a pseudo-inheritance system which automatically generates creator and
accessor functions. Since every node inherits from LispValue, the whole thing
is a mess. Here's a little anecdote:

    LispValue definition -- class used to support lisp structures
    in C.  This is here because we did not want to totally rewrite
    planner and executor code which depended on lisp structures when
    we ported postgres V1 from lisp to C. -cim 4/23/90