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324 lines
8.1 KiB
C
324 lines
8.1 KiB
C
/*-------------------------------------------------------------------------
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*
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* preptlist.c--
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* Routines to preprocess the parse tree target list
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/preptlist.c,v 1.2 1997/01/22 01:42:38 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include <string.h>
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#include "postgres.h"
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#include "nodes/pg_list.h"
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#include "nodes/relation.h"
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#include "nodes/primnodes.h"
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#include "nodes/parsenodes.h"
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#include "nodes/makefuncs.h"
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#include "utils/builtins.h"
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#include "utils/lsyscache.h"
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#include "utils/palloc.h"
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#include "parser/parsetree.h" /* for getrelid() */
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#include "parser/catalog_utils.h"
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#include "optimizer/internal.h"
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#include "optimizer/prep.h"
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#include "optimizer/clauses.h"
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#include "optimizer/tlist.h"
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static List *expand_targetlist(List *tlist, Oid relid, int command_type,
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Index result_relation);
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static List *replace_matching_resname(List *new_tlist,
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List *old_tlist);
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static List *new_relation_targetlist(Oid relid, Index rt_index,
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NodeTag node_type);
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/*
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* preprocess-targetlist--
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* Driver for preprocessing the parse tree targetlist.
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*
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* 1. Deal with appends and replaces by filling missing attributes
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* in the target list.
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* 2. Reset operator OIDs to the appropriate regproc ids.
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*
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* Returns the new targetlist.
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*/
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List *
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preprocess_targetlist(List *tlist,
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int command_type,
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Index result_relation,
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List *range_table)
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{
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List *expanded_tlist = NIL;
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Oid relid = InvalidOid;
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List *t_list = NIL;
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List *temp = NIL;
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if (result_relation>=1 && command_type != CMD_SELECT) {
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relid = getrelid(result_relation, range_table);
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}
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/*
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* for heap_formtuple to work, the targetlist must match the exact
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* order of the attributes. We also need to fill in the missing
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* attributes here. -ay 10/94
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*/
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expanded_tlist =
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expand_targetlist(tlist, relid, command_type, result_relation);
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/* XXX should the fix-opids be this early?? */
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/* was mapCAR */
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foreach (temp,expanded_tlist) {
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TargetEntry *tle = lfirst(temp);
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if (tle->expr)
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fix_opid(tle->expr);
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}
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t_list = copyObject(expanded_tlist);
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/* ------------------
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* for "replace" or "delete" queries, add ctid of the result
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* relation into the target list so that the ctid can get
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* propogate through the execution and in the end ExecReplace()
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* will find the right tuple to replace or delete. This
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* extra field will be removed in ExecReplace().
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* For convinient, we append this extra field to the end of
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* the target list.
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* ------------------
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*/
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if (command_type == CMD_UPDATE || command_type == CMD_DELETE) {
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TargetEntry *ctid;
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Resdom *resdom;
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Var *var;
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resdom = makeResdom(length(t_list) + 1,
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27,
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6,
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"ctid",
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0,
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0,
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1);
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var = makeVar(result_relation, -1, 27, result_relation, -1);
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ctid = makeNode(TargetEntry);
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ctid->resdom = resdom;
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ctid->expr = (Node *)var;
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t_list = lappend(t_list, ctid);
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}
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return(t_list);
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}
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/*****************************************************************************
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*
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* TARGETLIST EXPANSION
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*
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*****************************************************************************/
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/*
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* expand-targetlist--
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* Given a target list as generated by the parser and a result relation,
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* add targetlist entries for the attributes which have not been used.
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*
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* XXX This code is only supposed to work with unnested relations.
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*
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* 'tlist' is the original target list
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* 'relid' is the relid of the result relation
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* 'command' is the update command
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*
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* Returns the expanded target list, sorted in resno order.
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*/
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static List *
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expand_targetlist(List *tlist,
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Oid relid,
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int command_type,
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Index result_relation)
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{
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NodeTag node_type = T_Invalid;
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switch (command_type) {
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case CMD_INSERT:
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node_type = (NodeTag)T_Const;
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break;
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case CMD_UPDATE:
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node_type = (NodeTag)T_Var;
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break;
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}
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if(node_type != T_Invalid) {
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List *ntlist = new_relation_targetlist(relid,
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result_relation,
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node_type);
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return (replace_matching_resname(ntlist, tlist));
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} else {
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return (tlist);
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}
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}
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static List *
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replace_matching_resname(List *new_tlist, List *old_tlist)
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{
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List *temp, *i;
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List *t_list = NIL;
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foreach (i,new_tlist) {
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TargetEntry *new_tle = (TargetEntry *)lfirst(i);
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TargetEntry *matching_old_tl = NULL;
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foreach (temp, old_tlist) {
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TargetEntry *old_tle = (TargetEntry *)lfirst(temp);
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old_tle = lfirst(temp);
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if (!strcmp(old_tle->resdom->resname,
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new_tle->resdom->resname)) {
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matching_old_tl = old_tle;
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break;
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}
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}
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if(matching_old_tl) {
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matching_old_tl->resdom->resno =
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new_tle->resdom->resno;
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t_list = lappend(t_list, matching_old_tl);
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}
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else {
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t_list = lappend(t_list, new_tle);
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}
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}
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/*
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* It is possible that 'old_tlist' has some negative
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* attributes (i.e. negative resnos). This only happens
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* if this is a replace/append command and we explicitly
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* specify a system attribute. Of course this is not a very good
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* idea if this is a user query, but on the other hand the rule
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* manager uses this mechanism to replace rule locks.
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*
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* So, copy all these entries to the end of the target list
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* and set their 'resjunk' value to 1 to show that these are
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* special attributes and have to be treated specially by the
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* executor!
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*/
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foreach (temp, old_tlist) {
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TargetEntry *old_tle, *new_tl;
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Resdom *newresno;
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old_tle = lfirst(temp);
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if (old_tle->resdom->resno < 0) {
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newresno = (Resdom*) copyObject((Node*)old_tle->resdom);
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newresno->resno = length(t_list) +1;
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newresno->resjunk = 1;
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new_tl = MakeTLE(newresno, old_tle->expr);
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t_list = lappend(t_list, new_tl);
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}
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}
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return (t_list);
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}
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/*
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* new-relation-targetlist--
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* Generate a targetlist for the relation with relation OID 'relid'
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* and rangetable index 'rt-index'.
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*
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* Returns the new targetlist.
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*/
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static List *
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new_relation_targetlist(Oid relid, Index rt_index, NodeTag node_type)
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{
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AttrNumber attno;
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List *t_list = NIL;
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char *attname;
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Oid atttype = 0;
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int16 typlen = 0;
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bool attisset = false;
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/* Oid type_id; */
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/* type_id = RelationIdGetTypeId(relid); */
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for(attno=1; attno <= get_relnatts(relid); attno++) {
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attname = get_attname(/*type_id,*/ relid, attno);
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atttype = get_atttype(/*type_id,*/ relid, attno);
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/*
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* Since this is an append or replace, the size of any set
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* attribute is the size of the OID used to represent it.
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*/
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attisset = get_attisset(/* type_id,*/ relid, attname);
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if (attisset) {
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typlen = tlen(type("oid"));
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} else {
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typlen = get_typlen(atttype);
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}
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switch (node_type) {
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case T_Const:
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{
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struct varlena *typedefault = get_typdefault(atttype);
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int temp = 0;
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Const *temp2 = (Const*)NULL;
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TargetEntry *temp3 = (TargetEntry *)NULL;
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if (typedefault==NULL)
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temp = 0;
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else
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temp = typlen;
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temp2 = makeConst (atttype,
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temp,
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(Datum)typedefault,
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(typedefault == (struct varlena *)NULL),
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/* XXX this is bullshit */
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false,
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false, /* not a set */
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false);
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temp3 = MakeTLE (makeResdom(attno,
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atttype,
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typlen,
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attname,
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0,
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(Oid)0,
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0),
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(Node*)temp2);
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t_list = lappend(t_list,temp3);
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break;
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}
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case T_Var:
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{
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Var *temp_var = (Var*)NULL;
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TargetEntry *temp_list = NULL;
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temp_var =
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makeVar(rt_index, attno, atttype, rt_index, attno);
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temp_list = MakeTLE(makeResdom(attno,
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atttype,
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typlen,
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attname,
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0,
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(Oid)0,
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0),
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(Node*)temp_var);
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t_list = lappend(t_list,temp_list);
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break;
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}
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default: /* do nothing */
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break;
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}
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}
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return(t_list);
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}
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