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07a65b2255
Changes:
* Unique index capability works using the syntax 'create unique
index'.
* Duplicate OID's in the system tables are removed. I put
little scripts called 'duplicate_oids' and 'find_oid' in
include/catalog that help to find and remove duplicate OID's.
I also moved 'unused_oids' from backend/catalog to
include/catalog, since it has to be in the same directory
as the include files in order to work.
* The backend tries converting the name of a function or aggregate
to all lowercase if the original name given doesn't work (mostly
for compatibility with ODBC).
* You can 'SELECT NULL' to your heart's content.
* I put my _bt_updateitem fix in instead, which uses
_bt_insertonpg so that even if the new key is so big that
the page has to be split, everything still works.
* All literal references to system catalog OID's have been
replaced with references to define'd constants from the catalog
header files.
* I added a couple of node copy functions. I think this was a
preliminary attempt to get rules to work.
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||
|---|---|---|
| .. | ||
| copyfuncs.c | ||
| equalfuncs.c | ||
| list.c | ||
| Makefile | ||
| makefuncs.c | ||
| nodeFuncs.c | ||
| nodes.c | ||
| outfuncs.c | ||
| print.c | ||
| read.c | ||
| readfuncs.c | ||
| 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