postgresql/src/backend/nodes
Tom Lane f8942f4a15 Make eval_const_expressions() preserve typmod when simplifying something like
null::char(3) to a simple Const node.  (It already worked for non-null values,
but not when we skipped evaluation of a strict coercion function.)  This
prevents loss of typmod knowledge in situations such as exhibited in bug
#3598.  Unfortunately there seems no good way to fix that bug in 8.1 and 8.2,
because they simply don't carry a typmod for a plain Const node.

In passing I made all the other callers of makeNullConst supply "real" typmod
values too, though I think it probably doesn't matter anywhere else.
2007-09-06 17:31:58 +00:00
..
Makefile Remove remains of old depend target. 2007-01-20 17:16:17 +00:00
README make sure the $Id tags are converted to $PostgreSQL as well ... 2003-11-29 22:41:33 +00:00
bitmapset.c Fix several hash functions that were taking chintzy shortcuts instead of 2007-06-01 15:33:19 +00:00
copyfuncs.c Support SET FROM CURRENT in CREATE/ALTER FUNCTION, ALTER DATABASE, ALTER ROLE. 2007-09-03 18:46:30 +00:00
equalfuncs.c Support SET FROM CURRENT in CREATE/ALTER FUNCTION, ALTER DATABASE, ALTER ROLE. 2007-09-03 18:46:30 +00:00
list.c Update CVS HEAD for 2007 copyright. Back branches are typically not 2007-01-05 22:20:05 +00:00
makefuncs.c Make eval_const_expressions() preserve typmod when simplifying something like 2007-09-06 17:31:58 +00:00
nodeFuncs.c Update CVS HEAD for 2007 copyright. Back branches are typically not 2007-01-05 22:20:05 +00:00
nodes.c Update CVS HEAD for 2007 copyright. Back branches are typically not 2007-01-05 22:20:05 +00:00
outfuncs.c Rewrite make_outerjoininfo's construction of min_lefthand and min_righthand 2007-08-31 01:44:06 +00:00
params.c First phase of plan-invalidation project: create a plan cache management 2007-03-13 00:33:44 +00:00
print.c Turn the rangetable used by the executor into a flat list, and avoid storing 2007-02-22 22:00:26 +00:00
read.c Update CVS HEAD for 2007 copyright. Back branches are typically not 2007-01-05 22:20:05 +00:00
readfuncs.c Improve UPDATE/DELETE WHERE CURRENT OF so that they can be used from plpgsql 2007-06-11 22:22:42 +00:00
tidbitmap.c Fix dynahash.c to suppress hash bucket splits while a hash_seq_search() scan 2007-04-26 23:24:46 +00:00
value.c Update CVS HEAD for 2007 copyright. Back branches are typically not 2007-01-05 22:20:05 +00:00

README

*******************************************************************************
*                                                                             *
* 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