postgresql/src/backend/nodes
Tom Lane 9fa12ddda6 Add a paramtypmod field to Param nodes. This is dead weight for Params
representing externally-supplied values, since the APIs that carry such
values only specify type not typmod.  However, for PARAM_SUBLINK Params
it is handy to carry the typmod of the sublink's output column.  This
is a much cleaner solution for the recently reported 'could not find
pathkey item to sort' and 'failed to find unique expression in subplan
tlist' bugs than my original 8.2-compatible patch.  Besides, someday we
might want to support typmods for external parameters ...
2006-12-10 22:13:27 +00:00
..
bitmapset.c Update copyright for 2006. Update scripts. 2006-03-05 15:59:11 +00:00
copyfuncs.c Add a paramtypmod field to Param nodes. This is dead weight for Params 2006-12-10 22:13:27 +00:00
equalfuncs.c Add a paramtypmod field to Param nodes. This is dead weight for Params 2006-12-10 22:13:27 +00:00
list.c Update copyright for 2006. Update scripts. 2006-03-05 15:59:11 +00:00
Makefile Initial implementation of lossy-tuple-bitmap data structures. 2005-04-17 22:24:02 +00:00
makefuncs.c pgindent run for 8.2. 2006-10-04 00:30:14 +00:00
nodeFuncs.c Update copyright for 2006. Update scripts. 2006-03-05 15:59:11 +00:00
nodes.c Update copyright for 2006. Update scripts. 2006-03-05 15:59:11 +00:00
outfuncs.c Add a paramtypmod field to Param nodes. This is dead weight for Params 2006-12-10 22:13:27 +00:00
params.c pgindent run for 8.2. 2006-10-04 00:30:14 +00:00
print.c Add support for multi-row VALUES clauses as part of INSERT statements 2006-08-02 01:59:48 +00:00
read.c Replace strncpy with strlcpy in selected places that seem possibly relevant 2006-09-27 18:40:10 +00:00
readfuncs.c Add a paramtypmod field to Param nodes. This is dead weight for Params 2006-12-10 22:13:27 +00:00
README
tidbitmap.c More include file adjustments. 2006-07-13 17:47:02 +00:00
value.c Update copyright for 2006. Update scripts. 2006-03-05 15:59:11 +00:00

*******************************************************************************
*                                                                             *
* EXPLANATION OF THE NODE STRUCTURES                                          *
*    - Andrew Yu (11/94)                                                      *
*                                                                             *
* Copyright (c) 1994, Regents of the University of California                 *
*                                                                             *
* $PostgreSQL: pgsql/src/backend/nodes/README,v 1.2 2003/11/29 22:39:45 pgsql 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