mirror of
https://github.com/postgres/postgres.git
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6dc249610a
user is now defined in terms of the user id, the user name is only computed upon request (for display purposes). This is kind of the opposite of the previous state, which would maintain the user name and compute the user id for permission checks. Besides perhaps saving a few cycles (integer vs string), this now creates a single point of attack for changing the user id during a connection, for purposes of "setuid" functions, etc.
2026 lines
52 KiB
C
2026 lines
52 KiB
C
/*-------------------------------------------------------------------------
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*
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* rewriteHandler.c
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*
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* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
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* Portions 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/rewrite/rewriteHandler.c,v 1.79 2000/09/06 14:15:20 petere Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/heapam.h"
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#include "catalog/pg_operator.h"
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#include "catalog/pg_type.h"
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#include "miscadmin.h"
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#include "nodes/makefuncs.h"
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#include "optimizer/clauses.h"
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#include "optimizer/prep.h"
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#include "optimizer/var.h"
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#include "parser/analyze.h"
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#include "parser/parse_expr.h"
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#include "parser/parse_oper.h"
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#include "parser/parse_target.h"
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#include "parser/parsetree.h"
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#include "parser/parse_type.h"
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#include "rewrite/locks.h"
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#include "rewrite/rewriteManip.h"
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#include "utils/acl.h"
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#include "utils/lsyscache.h"
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extern void CheckSelectForUpdate(Query *rule_action); /* in analyze.c */
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/* macros borrowed from expression_tree_mutator */
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#define FLATCOPY(newnode, node, nodetype) \
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( (newnode) = makeNode(nodetype), \
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memcpy((newnode), (node), sizeof(nodetype)) )
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#define MUTATE(newfield, oldfield, fieldtype, mutator, context) \
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( (newfield) = (fieldtype) mutator((Node *) (oldfield), (context)) )
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static RewriteInfo *gatherRewriteMeta(Query *parsetree,
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Query *rule_action,
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Node *rule_qual,
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int rt_index,
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CmdType event,
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bool *instead_flag);
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static bool rangeTableEntry_used(Node *node, int rt_index, int sublevels_up);
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static bool attribute_used(Node *node, int rt_index, int attno,
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int sublevels_up);
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static bool modifyAggrefChangeVarnodes(Node *node, int rt_index, int new_index,
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int sublevels_up, int new_sublevels_up);
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static Node *modifyAggrefDropQual(Node *node, Node *targetNode);
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static SubLink *modifyAggrefMakeSublink(Aggref *aggref, Query *parsetree);
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static Node *modifyAggrefQual(Node *node, Query *parsetree);
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static Query *fireRIRrules(Query *parsetree);
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static Query *Except_Intersect_Rewrite(Query *parsetree);
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static void check_targetlists_are_compatible(List *prev_target,
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List *current_target);
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static void create_intersect_list(Node *ptr, List **intersect_list);
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static Node *intersect_tree_analyze(Node *tree, Node *first_select,
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Node *parsetree);
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/*
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* gatherRewriteMeta -
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* Gather meta information about parsetree, and rule. Fix rule body
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* and qualifier so that they can be mixed with the parsetree and
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* maintain semantic validity
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*/
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static RewriteInfo *
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gatherRewriteMeta(Query *parsetree,
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Query *rule_action,
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Node *rule_qual,
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int rt_index,
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CmdType event,
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bool *instead_flag)
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{
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RewriteInfo *info;
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int rt_length;
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int result_reln;
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info = (RewriteInfo *) palloc(sizeof(RewriteInfo));
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info->rt_index = rt_index;
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info->event = event;
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info->instead_flag = *instead_flag;
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info->rule_action = (Query *) copyObject(rule_action);
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info->rule_qual = (Node *) copyObject(rule_qual);
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if (info->rule_action == NULL)
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info->nothing = TRUE;
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else
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{
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info->nothing = FALSE;
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info->action = info->rule_action->commandType;
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info->current_varno = rt_index;
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info->rt = parsetree->rtable;
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rt_length = length(info->rt);
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info->rt = nconc(info->rt, copyObject(info->rule_action->rtable));
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info->new_varno = PRS2_NEW_VARNO + rt_length;
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OffsetVarNodes(info->rule_action->qual, rt_length, 0);
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OffsetVarNodes((Node *) info->rule_action->targetList, rt_length, 0);
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OffsetVarNodes(info->rule_qual, rt_length, 0);
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ChangeVarNodes((Node *) info->rule_action->qual,
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PRS2_OLD_VARNO + rt_length, rt_index, 0);
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ChangeVarNodes((Node *) info->rule_action->targetList,
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PRS2_OLD_VARNO + rt_length, rt_index, 0);
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ChangeVarNodes(info->rule_qual,
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PRS2_OLD_VARNO + rt_length, rt_index, 0);
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/*
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* bug here about replace CURRENT -- sort of replace current is
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* deprecated now so this code shouldn't really need to be so
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* clutzy but.....
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*/
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if (info->action != CMD_SELECT)
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{ /* i.e update XXXXX */
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int new_result_reln = 0;
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result_reln = info->rule_action->resultRelation;
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switch (result_reln)
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{
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case PRS2_OLD_VARNO:
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new_result_reln = rt_index;
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break;
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case PRS2_NEW_VARNO: /* XXX */
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default:
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new_result_reln = result_reln + rt_length;
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break;
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}
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info->rule_action->resultRelation = new_result_reln;
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}
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}
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return info;
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}
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/*
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* rangeTableEntry_used -
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* we need to process a RTE for RIR rules only if it is
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* referenced somewhere in var nodes of the query.
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*/
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typedef struct
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{
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int rt_index;
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int sublevels_up;
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} rangeTableEntry_used_context;
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static bool
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rangeTableEntry_used_walker(Node *node,
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rangeTableEntry_used_context *context)
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{
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if (node == NULL)
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return false;
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if (IsA(node, Var))
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{
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Var *var = (Var *) node;
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if (var->varlevelsup == context->sublevels_up &&
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var->varno == context->rt_index)
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return true;
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return false;
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}
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if (IsA(node, SubLink))
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{
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/*
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* Standard expression_tree_walker will not recurse into
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* subselect, but here we must do so.
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*/
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SubLink *sub = (SubLink *) node;
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if (rangeTableEntry_used_walker((Node *) (sub->lefthand), context))
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return true;
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if (rangeTableEntry_used((Node *) (sub->subselect),
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context->rt_index,
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context->sublevels_up + 1))
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return true;
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return false;
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}
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if (IsA(node, Query))
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{
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/* Reach here after recursing down into subselect above... */
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Query *qry = (Query *) node;
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if (rangeTableEntry_used_walker((Node *) (qry->targetList), context))
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return true;
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if (rangeTableEntry_used_walker((Node *) (qry->qual), context))
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return true;
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if (rangeTableEntry_used_walker((Node *) (qry->havingQual), context))
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return true;
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return false;
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}
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return expression_tree_walker(node, rangeTableEntry_used_walker,
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(void *) context);
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}
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static bool
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rangeTableEntry_used(Node *node, int rt_index, int sublevels_up)
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{
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rangeTableEntry_used_context context;
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context.rt_index = rt_index;
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context.sublevels_up = sublevels_up;
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return rangeTableEntry_used_walker(node, &context);
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}
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/*
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* attribute_used -
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* Check if a specific attribute number of a RTE is used
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* somewhere in the query
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*/
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typedef struct
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{
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int rt_index;
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int attno;
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int sublevels_up;
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} attribute_used_context;
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static bool
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attribute_used_walker(Node *node,
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attribute_used_context *context)
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{
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if (node == NULL)
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return false;
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if (IsA(node, Var))
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{
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Var *var = (Var *) node;
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if (var->varlevelsup == context->sublevels_up &&
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var->varno == context->rt_index &&
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var->varattno == context->attno)
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return true;
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return false;
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}
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if (IsA(node, SubLink))
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{
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/*
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* Standard expression_tree_walker will not recurse into
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* subselect, but here we must do so.
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*/
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SubLink *sub = (SubLink *) node;
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if (attribute_used_walker((Node *) (sub->lefthand), context))
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return true;
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if (attribute_used((Node *) (sub->subselect),
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context->rt_index,
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context->attno,
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context->sublevels_up + 1))
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return true;
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return false;
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}
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if (IsA(node, Query))
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{
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/* Reach here after recursing down into subselect above... */
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Query *qry = (Query *) node;
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if (attribute_used_walker((Node *) (qry->targetList), context))
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return true;
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if (attribute_used_walker((Node *) (qry->qual), context))
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return true;
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if (attribute_used_walker((Node *) (qry->havingQual), context))
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return true;
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return false;
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}
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return expression_tree_walker(node, attribute_used_walker,
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(void *) context);
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}
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static bool
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attribute_used(Node *node, int rt_index, int attno, int sublevels_up)
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{
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attribute_used_context context;
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context.rt_index = rt_index;
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context.attno = attno;
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context.sublevels_up = sublevels_up;
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return attribute_used_walker(node, &context);
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}
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/*
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* modifyAggrefChangeVarnodes -
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* Change the var nodes in a sublink created for an aggregate column
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* used in the qualification to point to the correct local RTE.
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*
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* XXX if we still need this after redoing querytree design, it should
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* be combined with ChangeVarNodes, which is the same thing except for
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* not having the option to adjust the vars' varlevelsup.
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*
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* NOTE: although this has the form of a walker, we cheat and modify the
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* Var nodes in-place. The given expression tree should have been copied
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* earlier to ensure that no unwanted side-effects occur!
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*/
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typedef struct
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{
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int rt_index;
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int new_index;
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int sublevels_up;
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int new_sublevels_up;
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} modifyAggrefChangeVarnodes_context;
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static bool
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modifyAggrefChangeVarnodes_walker(Node *node,
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modifyAggrefChangeVarnodes_context *context)
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{
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if (node == NULL)
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return false;
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if (IsA(node, Var))
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{
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Var *var = (Var *) node;
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if (var->varlevelsup == context->sublevels_up &&
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var->varno == context->rt_index)
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{
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var->varno = context->new_index;
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var->varnoold = context->new_index;
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var->varlevelsup = context->new_sublevels_up;
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}
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return false;
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}
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if (IsA(node, SubLink))
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{
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/*
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* Standard expression_tree_walker will not recurse into
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* subselect, but here we must do so.
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*/
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SubLink *sub = (SubLink *) node;
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if (modifyAggrefChangeVarnodes_walker((Node *) (sub->lefthand),
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context))
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return true;
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if (modifyAggrefChangeVarnodes((Node *) (sub->subselect),
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context->rt_index,
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context->new_index,
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context->sublevels_up + 1,
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context->new_sublevels_up + 1))
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return true;
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return false;
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}
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if (IsA(node, Query))
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{
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/* Reach here after recursing down into subselect above... */
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Query *qry = (Query *) node;
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if (modifyAggrefChangeVarnodes_walker((Node *) (qry->targetList),
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context))
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return true;
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if (modifyAggrefChangeVarnodes_walker((Node *) (qry->qual),
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context))
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return true;
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if (modifyAggrefChangeVarnodes_walker((Node *) (qry->havingQual),
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context))
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return true;
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return false;
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}
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return expression_tree_walker(node, modifyAggrefChangeVarnodes_walker,
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(void *) context);
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}
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static bool
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modifyAggrefChangeVarnodes(Node *node, int rt_index, int new_index,
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int sublevels_up, int new_sublevels_up)
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{
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modifyAggrefChangeVarnodes_context context;
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context.rt_index = rt_index;
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context.new_index = new_index;
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context.sublevels_up = sublevels_up;
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context.new_sublevels_up = new_sublevels_up;
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return modifyAggrefChangeVarnodes_walker(node, &context);
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}
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/*
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* modifyAggrefDropQual -
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* remove the pure aggref clause from a qualification
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*
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* targetNode is an Aggref node somewhere within the given expression tree.
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* Find the boolean operator that's presumably somewhere above it, and replace
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* that whole operator expression with a constant TRUE. (This is NOT really
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* quite the right thing, but it handles simple cases. This whole set of
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* Aggref-in-qual routines needs to be thrown away when we can do subselects
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* in FROM.)
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*
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* The return tree is a modified copy of the given tree; the given tree
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* is not altered.
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*
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* Note: we don't recurse into subselects looking for targetNode; that's
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* not necessary in the current usage, since in fact targetNode will be
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* within the same select level as the given toplevel node.
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*/
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static Node *
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modifyAggrefDropQual(Node *node, Node *targetNode)
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{
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if (node == NULL)
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return NULL;
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if (node == targetNode)
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{
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/* Oops, it's not inside an Expr we can rearrange... */
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elog(ERROR, "Cannot handle aggregate function inserted at this place in WHERE clause");
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}
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if (IsA(node, Expr))
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{
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Expr *expr = (Expr *) node;
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List *i;
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foreach(i, expr->args)
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{
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if (((Node *) lfirst(i)) == targetNode)
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{
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/* Found the parent expression containing the Aggref */
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if (expr->typeOid != BOOLOID)
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elog(ERROR,
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"aggregate function in qual must be argument of boolean operator");
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return (Node *) makeConst(BOOLOID, 1, (Datum) true,
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false, true, false, false);
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}
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}
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/* else this isn't the expr we want, keep going */
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}
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return expression_tree_mutator(node, modifyAggrefDropQual,
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(void *) targetNode);
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}
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/*
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* modifyAggrefMakeSublink -
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* Create a sublink node for a qualification expression that
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* uses an aggregate column of a view
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*/
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static SubLink *
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modifyAggrefMakeSublink(Aggref *aggref, Query *parsetree)
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{
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List *aggVarNos;
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/* rte points to old structure: */
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RangeTblEntry *rte;
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/* these point to newly-created structures: */
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Query *subquery;
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SubLink *sublink;
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TargetEntry *tle;
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Resdom *resdom;
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aggVarNos = pull_varnos(aggref->target);
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if (length(aggVarNos) != 1)
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elog(ERROR, "rewrite: aggregates of views only allowed on single tables for now");
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rte = rt_fetch(lfirsti(aggVarNos), parsetree->rtable);
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resdom = makeNode(Resdom);
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resdom->resno = 1;
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resdom->restype = aggref->aggtype;
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resdom->restypmod = -1;
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resdom->resname = pstrdup("<noname>");
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resdom->reskey = 0;
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resdom->reskeyop = 0;
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resdom->resjunk = false;
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tle = makeNode(TargetEntry);
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tle->resdom = resdom;
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tle->expr = copyObject(aggref); /* make a modifiable copy! */
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subquery = makeNode(Query);
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sublink = makeNode(SubLink);
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sublink->subLinkType = EXPR_SUBLINK;
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sublink->useor = false;
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sublink->lefthand = NIL;
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sublink->oper = NIL;
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sublink->subselect = (Node *) subquery;
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subquery->commandType = CMD_SELECT;
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subquery->utilityStmt = NULL;
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subquery->resultRelation = 0;
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subquery->into = NULL;
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subquery->isPortal = FALSE;
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subquery->isBinary = FALSE;
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subquery->isTemp = FALSE;
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subquery->unionall = FALSE;
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subquery->distinctClause = NIL;
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subquery->sortClause = NIL;
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subquery->rtable = lcons(copyObject(rte), NIL);
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subquery->targetList = lcons(tle, NIL);
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subquery->qual = modifyAggrefDropQual((Node *) parsetree->qual,
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(Node *) aggref);
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/*
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* If there are still aggs in the subselect's qual, give up. Recursing
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* would be a bad idea --- we'd likely produce an infinite recursion.
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* This whole technique is a crock, really...
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*/
|
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if (checkExprHasAggs(subquery->qual))
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elog(ERROR, "Cannot handle multiple aggregate functions in WHERE clause");
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subquery->groupClause = NIL;
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subquery->havingQual = NULL;
|
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subquery->hasAggs = TRUE;
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subquery->hasSubLinks = checkExprHasSubLink(subquery->qual);
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subquery->unionClause = NULL;
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|
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/* Increment all varlevelsup fields in the new subquery */
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IncrementVarSublevelsUp((Node *) subquery, 1, 0);
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|
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/*
|
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* Replace references to the target table with correct local varno, 1.
|
|
* Note that because of previous line, these references have
|
|
* varlevelsup = 1, which must be changed to 0.
|
|
*/
|
|
modifyAggrefChangeVarnodes((Node *) subquery,
|
|
lfirsti(aggVarNos), 1,
|
|
1, 0);
|
|
|
|
return sublink;
|
|
}
|
|
|
|
|
|
/*
|
|
* modifyAggrefQual -
|
|
* Search for qualification expressions that contain aggregate
|
|
* functions and substitute them by sublinks. These expressions
|
|
* originally come from qualifications that use aggregate columns
|
|
* of a view.
|
|
*
|
|
* The return value is a modified copy of the given expression tree.
|
|
*/
|
|
static Node *
|
|
modifyAggrefQual(Node *node, Query *parsetree)
|
|
{
|
|
if (node == NULL)
|
|
return NULL;
|
|
if (IsA(node, Aggref))
|
|
{
|
|
SubLink *sub = modifyAggrefMakeSublink((Aggref *) node, parsetree);
|
|
|
|
parsetree->hasSubLinks = true;
|
|
return (Node *) sub;
|
|
}
|
|
|
|
/*
|
|
* Otherwise, fall through and copy the expr normally.
|
|
*
|
|
* We do NOT recurse into subselects in this routine. It's sufficient to
|
|
* get rid of aggregates that are in the qual expression proper.
|
|
*/
|
|
return expression_tree_mutator(node, modifyAggrefQual,
|
|
(void *) parsetree);
|
|
}
|
|
|
|
|
|
static Node *
|
|
FindMatchingTLEntry(List *tlist, char *e_attname)
|
|
{
|
|
List *i;
|
|
|
|
foreach(i, tlist)
|
|
{
|
|
TargetEntry *tle = lfirst(i);
|
|
char *resname;
|
|
|
|
resname = tle->resdom->resname;
|
|
if (!strcmp(e_attname, resname))
|
|
return (tle->expr);
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
|
|
static Node *
|
|
make_null(Oid type)
|
|
{
|
|
Const *c = makeNode(Const);
|
|
|
|
c->consttype = type;
|
|
c->constlen = get_typlen(type);
|
|
c->constvalue = PointerGetDatum(NULL);
|
|
c->constisnull = true;
|
|
c->constbyval = get_typbyval(type);
|
|
return (Node *) c;
|
|
}
|
|
|
|
|
|
/*
|
|
* apply_RIR_view
|
|
* Replace Vars matching a given RT index with copies of TL expressions.
|
|
*/
|
|
|
|
typedef struct
|
|
{
|
|
int rt_index;
|
|
int sublevels_up;
|
|
RangeTblEntry *rte;
|
|
List *tlist;
|
|
int *modified;
|
|
} apply_RIR_view_context;
|
|
|
|
static Node *
|
|
apply_RIR_view_mutator(Node *node,
|
|
apply_RIR_view_context *context)
|
|
{
|
|
if (node == NULL)
|
|
return NULL;
|
|
if (IsA(node, Var))
|
|
{
|
|
Var *var = (Var *) node;
|
|
|
|
if (var->varlevelsup == context->sublevels_up &&
|
|
var->varno == context->rt_index)
|
|
{
|
|
Node *expr;
|
|
|
|
if (var->varattno < 0)
|
|
elog(ERROR, "system column %s not available - %s is a view",
|
|
get_attname(context->rte->relid, var->varattno),
|
|
context->rte->relname);
|
|
|
|
expr = FindMatchingTLEntry(context->tlist,
|
|
get_attname(context->rte->relid,
|
|
var->varattno));
|
|
if (expr == NULL)
|
|
{
|
|
/* XXX shouldn't this be an error condition? */
|
|
return make_null(var->vartype);
|
|
}
|
|
|
|
/* Make a copy of the tlist item to return */
|
|
expr = copyObject(expr);
|
|
/* Adjust varlevelsup if tlist item is from higher query level */
|
|
if (var->varlevelsup > 0)
|
|
IncrementVarSublevelsUp(expr, var->varlevelsup, 0);
|
|
|
|
*(context->modified) = true;
|
|
return (Node *) expr;
|
|
}
|
|
/* otherwise fall through to copy the var normally */
|
|
}
|
|
|
|
/*
|
|
* Since expression_tree_mutator won't touch subselects, we have to
|
|
* handle them specially.
|
|
*/
|
|
if (IsA(node, SubLink))
|
|
{
|
|
SubLink *sublink = (SubLink *) node;
|
|
SubLink *newnode;
|
|
|
|
FLATCOPY(newnode, sublink, SubLink);
|
|
MUTATE(newnode->lefthand, sublink->lefthand, List *,
|
|
apply_RIR_view_mutator, context);
|
|
context->sublevels_up++;
|
|
MUTATE(newnode->subselect, sublink->subselect, Node *,
|
|
apply_RIR_view_mutator, context);
|
|
context->sublevels_up--;
|
|
return (Node *) newnode;
|
|
}
|
|
if (IsA(node, Query))
|
|
{
|
|
Query *query = (Query *) node;
|
|
Query *newnode;
|
|
|
|
FLATCOPY(newnode, query, Query);
|
|
MUTATE(newnode->targetList, query->targetList, List *,
|
|
apply_RIR_view_mutator, context);
|
|
MUTATE(newnode->qual, query->qual, Node *,
|
|
apply_RIR_view_mutator, context);
|
|
MUTATE(newnode->havingQual, query->havingQual, Node *,
|
|
apply_RIR_view_mutator, context);
|
|
return (Node *) newnode;
|
|
}
|
|
return expression_tree_mutator(node, apply_RIR_view_mutator,
|
|
(void *) context);
|
|
}
|
|
|
|
static Node *
|
|
apply_RIR_view(Node *node, int rt_index, RangeTblEntry *rte, List *tlist,
|
|
int *modified, int sublevels_up)
|
|
{
|
|
apply_RIR_view_context context;
|
|
|
|
context.rt_index = rt_index;
|
|
context.sublevels_up = sublevels_up;
|
|
context.rte = rte;
|
|
context.tlist = tlist;
|
|
context.modified = modified;
|
|
|
|
return apply_RIR_view_mutator(node, &context);
|
|
}
|
|
|
|
|
|
static Query *
|
|
ApplyRetrieveRule(Query *parsetree,
|
|
RewriteRule *rule,
|
|
int rt_index,
|
|
int relation_level,
|
|
Relation relation,
|
|
bool relWasInJoinSet)
|
|
{
|
|
Query *rule_action = NULL;
|
|
Node *rule_qual;
|
|
List *rtable,
|
|
*addedrtable,
|
|
*l;
|
|
int nothing,
|
|
rt_length;
|
|
int modified = false;
|
|
int badsql = false;
|
|
|
|
rule_qual = rule->qual;
|
|
if (rule->actions)
|
|
{
|
|
if (length(rule->actions) > 1) /* ??? because we don't handle
|
|
* rules with more than one
|
|
* action? -ay */
|
|
|
|
return parsetree;
|
|
rule_action = copyObject(lfirst(rule->actions));
|
|
nothing = FALSE;
|
|
}
|
|
else
|
|
nothing = TRUE;
|
|
|
|
rtable = copyObject(parsetree->rtable);
|
|
rt_length = length(rtable); /* original length, not counting rule */
|
|
|
|
addedrtable = copyObject(rule_action->rtable);
|
|
|
|
/*
|
|
* If the original rel wasn't in the join set, none of its spawn is.
|
|
* If it was, then leave the spawn's flags as they are.
|
|
*/
|
|
if (!relWasInJoinSet)
|
|
{
|
|
foreach(l, addedrtable)
|
|
{
|
|
RangeTblEntry *rte = lfirst(l);
|
|
|
|
rte->inJoinSet = false;
|
|
}
|
|
}
|
|
|
|
rtable = nconc(rtable, addedrtable);
|
|
parsetree->rtable = rtable;
|
|
|
|
/* FOR UPDATE of view... */
|
|
foreach(l, parsetree->rowMark)
|
|
{
|
|
if (((RowMark *) lfirst(l))->rti == rt_index)
|
|
break;
|
|
}
|
|
if (l != NULL) /* oh, hell -:) */
|
|
{
|
|
RowMark *newrm;
|
|
Index rti = 1;
|
|
List *l2;
|
|
|
|
CheckSelectForUpdate(rule_action);
|
|
|
|
/*
|
|
* We believe that rt_index is VIEW - nothing should be marked for
|
|
* VIEW, but ACL check must be done. As for real tables of VIEW -
|
|
* their rows must be marked, but we have to skip ACL check for
|
|
* them.
|
|
*/
|
|
((RowMark *) lfirst(l))->info &= ~ROW_MARK_FOR_UPDATE;
|
|
|
|
foreach(l2, rule_action->rtable)
|
|
{
|
|
|
|
/*
|
|
* RTable of VIEW has two entries of VIEW itself - we use
|
|
* relid to skip them.
|
|
*/
|
|
if (relation->rd_id != ((RangeTblEntry *) lfirst(l2))->relid)
|
|
{
|
|
newrm = makeNode(RowMark);
|
|
newrm->rti = rti + rt_length;
|
|
newrm->info = ROW_MARK_FOR_UPDATE;
|
|
lnext(l) = lcons(newrm, lnext(l));
|
|
l = lnext(l);
|
|
}
|
|
rti++;
|
|
}
|
|
}
|
|
|
|
rule_action->rtable = rtable;
|
|
OffsetVarNodes((Node *) rule_qual, rt_length, 0);
|
|
OffsetVarNodes((Node *) rule_action, rt_length, 0);
|
|
|
|
ChangeVarNodes((Node *) rule_qual,
|
|
PRS2_OLD_VARNO + rt_length, rt_index, 0);
|
|
ChangeVarNodes((Node *) rule_action,
|
|
PRS2_OLD_VARNO + rt_length, rt_index, 0);
|
|
|
|
if (relation_level)
|
|
{
|
|
RangeTblEntry *rte = rt_fetch(rt_index, rtable);
|
|
|
|
parsetree = (Query *) apply_RIR_view((Node *) parsetree,
|
|
rt_index, rte,
|
|
rule_action->targetList,
|
|
&modified, 0);
|
|
rule_action = (Query *) apply_RIR_view((Node *) rule_action,
|
|
rt_index, rte,
|
|
rule_action->targetList,
|
|
&modified, 0);
|
|
/* always apply quals of relation-level rules, whether we found a
|
|
* var to substitute or not.
|
|
*/
|
|
modified = true;
|
|
}
|
|
else
|
|
{
|
|
HandleRIRAttributeRule(parsetree, rtable, rule_action->targetList,
|
|
rt_index, rule->attrno, &modified, &badsql);
|
|
/* quals will be inserted only if we found uses of the attribute */
|
|
}
|
|
if (modified && !badsql)
|
|
{
|
|
AddQual(parsetree, rule_action->qual);
|
|
AddGroupClause(parsetree, rule_action->groupClause,
|
|
rule_action->targetList);
|
|
AddHavingQual(parsetree, rule_action->havingQual);
|
|
parsetree->hasAggs = (rule_action->hasAggs || parsetree->hasAggs);
|
|
parsetree->hasSubLinks = (rule_action->hasSubLinks || parsetree->hasSubLinks);
|
|
}
|
|
|
|
return parsetree;
|
|
}
|
|
|
|
|
|
/*
|
|
* fireRIRonSubselect -
|
|
* Apply fireRIRrules() to each subselect found in the given tree.
|
|
*
|
|
* NOTE: although this has the form of a walker, we cheat and modify the
|
|
* SubLink nodes in-place. It is caller's responsibility to ensure that
|
|
* no unwanted side-effects occur!
|
|
*/
|
|
static bool
|
|
fireRIRonSubselect(Node *node, void *context)
|
|
{
|
|
if (node == NULL)
|
|
return false;
|
|
if (IsA(node, SubLink))
|
|
{
|
|
SubLink *sub = (SubLink *) node;
|
|
Query *qry;
|
|
|
|
/* Process lefthand args */
|
|
if (fireRIRonSubselect((Node *) (sub->lefthand), context))
|
|
return true;
|
|
/* Do what we came for */
|
|
qry = fireRIRrules((Query *) (sub->subselect));
|
|
sub->subselect = (Node *) qry;
|
|
/* Need not recurse into subselect, because fireRIRrules did it */
|
|
return false;
|
|
}
|
|
if (IsA(node, Query))
|
|
{
|
|
/* Reach here when called from fireRIRrules */
|
|
Query *qry = (Query *) node;
|
|
|
|
if (fireRIRonSubselect((Node *) (qry->targetList), context))
|
|
return true;
|
|
if (fireRIRonSubselect((Node *) (qry->qual), context))
|
|
return true;
|
|
if (fireRIRonSubselect((Node *) (qry->havingQual), context))
|
|
return true;
|
|
return false;
|
|
}
|
|
return expression_tree_walker(node, fireRIRonSubselect,
|
|
(void *) context);
|
|
}
|
|
|
|
|
|
/*
|
|
* fireRIRrules -
|
|
* Apply all RIR rules on each rangetable entry in a query
|
|
*/
|
|
static Query *
|
|
fireRIRrules(Query *parsetree)
|
|
{
|
|
int rt_index;
|
|
RangeTblEntry *rte;
|
|
Relation rel;
|
|
List *locks;
|
|
RuleLock *rules;
|
|
RewriteRule *rule;
|
|
RewriteRule RIRonly;
|
|
bool relWasInJoinSet;
|
|
int i;
|
|
List *l;
|
|
|
|
/*
|
|
* don't try to convert this into a foreach loop, because rtable list
|
|
* can get changed each time through...
|
|
*/
|
|
rt_index = 0;
|
|
while (rt_index < length(parsetree->rtable))
|
|
{
|
|
++rt_index;
|
|
|
|
rte = rt_fetch(rt_index, parsetree->rtable);
|
|
|
|
/*
|
|
* If the table is not referenced in the query, then we ignore it.
|
|
* This prevents infinite expansion loop due to new rtable entries
|
|
* inserted by expansion of a rule. A table is referenced if it is
|
|
* part of the join set (a source table), or is the result table,
|
|
* or is referenced by any Var nodes.
|
|
*/
|
|
if (!rte->inJoinSet && rt_index != parsetree->resultRelation &&
|
|
!rangeTableEntry_used((Node *) parsetree, rt_index, 0))
|
|
continue;
|
|
|
|
rel = heap_openr(rte->relname, AccessShareLock);
|
|
rules = rel->rd_rules;
|
|
if (rules == NULL)
|
|
{
|
|
heap_close(rel, AccessShareLock);
|
|
continue;
|
|
}
|
|
|
|
relWasInJoinSet = rte->inJoinSet; /* save before possibly
|
|
* clearing */
|
|
|
|
/*
|
|
* Collect the RIR rules that we must apply
|
|
*/
|
|
locks = NIL;
|
|
for (i = 0; i < rules->numLocks; i++)
|
|
{
|
|
rule = rules->rules[i];
|
|
if (rule->event != CMD_SELECT)
|
|
continue;
|
|
|
|
if (rule->attrno > 0)
|
|
{
|
|
/* per-attr rule; do we need it? */
|
|
if (!attribute_used((Node *) parsetree,
|
|
rt_index,
|
|
rule->attrno, 0))
|
|
continue;
|
|
}
|
|
else
|
|
{
|
|
|
|
/*
|
|
* Rel-wide ON SELECT DO INSTEAD means this is a view.
|
|
* Remove the view from the planner's join target set, or
|
|
* we'll get no rows out because view itself is empty!
|
|
*/
|
|
if (rule->isInstead)
|
|
rte->inJoinSet = false;
|
|
}
|
|
|
|
locks = lappend(locks, rule);
|
|
}
|
|
|
|
/*
|
|
* Check permissions
|
|
*/
|
|
checkLockPerms(locks, parsetree, rt_index);
|
|
|
|
/*
|
|
* Now apply them
|
|
*/
|
|
foreach(l, locks)
|
|
{
|
|
rule = lfirst(l);
|
|
|
|
RIRonly.event = rule->event;
|
|
RIRonly.attrno = rule->attrno;
|
|
RIRonly.qual = rule->qual;
|
|
RIRonly.actions = rule->actions;
|
|
|
|
parsetree = ApplyRetrieveRule(parsetree,
|
|
&RIRonly,
|
|
rt_index,
|
|
RIRonly.attrno == -1,
|
|
rel,
|
|
relWasInJoinSet);
|
|
}
|
|
|
|
heap_close(rel, AccessShareLock);
|
|
}
|
|
|
|
if (parsetree->hasAggs)
|
|
parsetree->qual = modifyAggrefQual(parsetree->qual, parsetree);
|
|
|
|
if (parsetree->hasSubLinks)
|
|
fireRIRonSubselect((Node *) parsetree, NULL);
|
|
|
|
return parsetree;
|
|
}
|
|
|
|
|
|
/*
|
|
* idea is to fire regular rules first, then qualified instead
|
|
* rules and unqualified instead rules last. Any lemming is counted for.
|
|
*/
|
|
static List *
|
|
orderRules(List *locks)
|
|
{
|
|
List *regular = NIL;
|
|
List *instead_rules = NIL;
|
|
List *instead_qualified = NIL;
|
|
List *i;
|
|
|
|
foreach(i, locks)
|
|
{
|
|
RewriteRule *rule_lock = (RewriteRule *) lfirst(i);
|
|
|
|
if (rule_lock->isInstead)
|
|
{
|
|
if (rule_lock->qual == NULL)
|
|
instead_rules = lappend(instead_rules, rule_lock);
|
|
else
|
|
instead_qualified = lappend(instead_qualified, rule_lock);
|
|
}
|
|
else
|
|
regular = lappend(regular, rule_lock);
|
|
}
|
|
regular = nconc(regular, instead_qualified);
|
|
return nconc(regular, instead_rules);
|
|
}
|
|
|
|
|
|
|
|
static Query *
|
|
CopyAndAddQual(Query *parsetree,
|
|
List *actions,
|
|
Node *rule_qual,
|
|
int rt_index,
|
|
CmdType event)
|
|
{
|
|
Query *new_tree = (Query *) copyObject(parsetree);
|
|
Node *new_qual = NULL;
|
|
Query *rule_action = NULL;
|
|
|
|
if (actions)
|
|
rule_action = lfirst(actions);
|
|
if (rule_qual != NULL)
|
|
new_qual = (Node *) copyObject(rule_qual);
|
|
if (rule_action != NULL)
|
|
{
|
|
List *rtable;
|
|
int rt_length;
|
|
|
|
rtable = new_tree->rtable;
|
|
rt_length = length(rtable);
|
|
rtable = nconc(rtable, copyObject(rule_action->rtable));
|
|
new_tree->rtable = rtable;
|
|
OffsetVarNodes(new_qual, rt_length, 0);
|
|
ChangeVarNodes(new_qual, PRS2_OLD_VARNO + rt_length, rt_index, 0);
|
|
}
|
|
/* XXX -- where current doesn't work for instead nothing.... yet */
|
|
AddNotQual(new_tree, new_qual);
|
|
|
|
return new_tree;
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
* fireRules -
|
|
* Iterate through rule locks applying rules.
|
|
* All rules create their own parsetrees. Instead rules
|
|
* with rule qualification save the original parsetree
|
|
* and add their negated qualification to it. Real instead
|
|
* rules finally throw away the original parsetree.
|
|
*
|
|
* remember: reality is for dead birds -- glass
|
|
*
|
|
*/
|
|
static List *
|
|
fireRules(Query *parsetree,
|
|
int rt_index,
|
|
CmdType event,
|
|
bool *instead_flag,
|
|
List *locks,
|
|
List **qual_products)
|
|
{
|
|
RewriteInfo *info;
|
|
List *results = NIL;
|
|
List *i;
|
|
|
|
/* choose rule to fire from list of rules */
|
|
if (locks == NIL)
|
|
return NIL;
|
|
|
|
locks = orderRules(locks); /* real instead rules last */
|
|
foreach(i, locks)
|
|
{
|
|
RewriteRule *rule_lock = (RewriteRule *) lfirst(i);
|
|
Node *qual,
|
|
*event_qual;
|
|
List *actions;
|
|
List *r;
|
|
|
|
/*
|
|
* Instead rules change the resultRelation of the query. So the
|
|
* permission checks on the initial resultRelation would never be
|
|
* done (this is normally done in the executor deep down). So we
|
|
* must do it here. The result relations resulting from earlier
|
|
* rewrites are already checked against the rules eventrelation
|
|
* owner (during matchLocks) and have the skipAcl flag set.
|
|
*/
|
|
if (rule_lock->isInstead &&
|
|
parsetree->commandType != CMD_SELECT)
|
|
{
|
|
RangeTblEntry *rte;
|
|
int32 acl_rc;
|
|
int32 reqperm;
|
|
|
|
switch (parsetree->commandType)
|
|
{
|
|
case CMD_INSERT:
|
|
reqperm = ACL_AP;
|
|
break;
|
|
default:
|
|
reqperm = ACL_WR;
|
|
break;
|
|
}
|
|
|
|
rte = rt_fetch(parsetree->resultRelation, parsetree->rtable);
|
|
if (!rte->skipAcl)
|
|
{
|
|
acl_rc = pg_aclcheck(rte->relname,
|
|
GetUserId(), reqperm);
|
|
if (acl_rc != ACLCHECK_OK)
|
|
{
|
|
elog(ERROR, "%s: %s",
|
|
rte->relname,
|
|
aclcheck_error_strings[acl_rc]);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* multiple rule action time */
|
|
*instead_flag = rule_lock->isInstead;
|
|
event_qual = rule_lock->qual;
|
|
actions = rule_lock->actions;
|
|
if (event_qual != NULL && *instead_flag)
|
|
{
|
|
Query *qual_product;
|
|
RewriteInfo qual_info;
|
|
|
|
/* ----------
|
|
* If there are instead rules with qualifications,
|
|
* the original query is still performed. But all
|
|
* the negated rule qualifications of the instead
|
|
* rules are added so it does its actions only
|
|
* in cases where the rule quals of all instead
|
|
* rules are false. Think of it as the default
|
|
* action in a case. We save this in *qual_products
|
|
* so deepRewriteQuery() can add it to the query
|
|
* list after we mangled it up enough.
|
|
* ----------
|
|
*/
|
|
if (*qual_products == NIL)
|
|
qual_product = parsetree;
|
|
else
|
|
qual_product = (Query *) nth(0, *qual_products);
|
|
|
|
MemSet(&qual_info, 0, sizeof(qual_info));
|
|
qual_info.event = qual_product->commandType;
|
|
qual_info.current_varno = rt_index;
|
|
qual_info.new_varno = length(qual_product->rtable) + 2;
|
|
|
|
qual_product = CopyAndAddQual(qual_product,
|
|
actions,
|
|
event_qual,
|
|
rt_index,
|
|
event);
|
|
|
|
qual_info.rule_action = qual_product;
|
|
|
|
if (event == CMD_INSERT || event == CMD_UPDATE)
|
|
FixNew(&qual_info, qual_product);
|
|
|
|
*qual_products = lappend(NIL, qual_product);
|
|
}
|
|
|
|
foreach(r, actions)
|
|
{
|
|
Query *rule_action = lfirst(r);
|
|
Node *rule_qual = copyObject(event_qual);
|
|
|
|
if (rule_action->commandType == CMD_NOTHING)
|
|
continue;
|
|
|
|
/*--------------------------------------------------
|
|
* We copy the qualifications of the parsetree
|
|
* to the action and vice versa. So force
|
|
* hasSubLinks if one of them has it.
|
|
*
|
|
* As of 6.4 only parsetree qualifications can
|
|
* have sublinks. If this changes, we must make
|
|
* this a node lookup at the end of rewriting.
|
|
*
|
|
* Jan
|
|
*--------------------------------------------------
|
|
*/
|
|
if (parsetree->hasSubLinks && !rule_action->hasSubLinks)
|
|
{
|
|
rule_action = copyObject(rule_action);
|
|
rule_action->hasSubLinks = TRUE;
|
|
}
|
|
if (!parsetree->hasSubLinks && rule_action->hasSubLinks)
|
|
parsetree->hasSubLinks = TRUE;
|
|
|
|
/*--------------------------------------------------
|
|
* Step 1:
|
|
* Rewrite current.attribute or current to tuple variable
|
|
* this appears to be done in parser?
|
|
*--------------------------------------------------
|
|
*/
|
|
info = gatherRewriteMeta(parsetree, rule_action, rule_qual,
|
|
rt_index, event, instead_flag);
|
|
|
|
/* handle escapable cases, or those handled by other code */
|
|
if (info->nothing)
|
|
{
|
|
if (*instead_flag)
|
|
return NIL;
|
|
else
|
|
continue;
|
|
}
|
|
|
|
if (info->action == info->event &&
|
|
info->event == CMD_SELECT)
|
|
continue;
|
|
|
|
/*
|
|
* Event Qualification forces copying of parsetree and
|
|
* splitting into two queries one w/rule_qual, one w/NOT
|
|
* rule_qual. Also add user query qual onto rule action
|
|
*/
|
|
qual = parsetree->qual;
|
|
AddQual(info->rule_action, qual);
|
|
|
|
if (info->rule_qual != NULL)
|
|
AddQual(info->rule_action, info->rule_qual);
|
|
|
|
/*--------------------------------------------------
|
|
* Step 2:
|
|
* Rewrite new.attribute w/ right hand side of target-list
|
|
* entry for appropriate field name in insert/update
|
|
*--------------------------------------------------
|
|
*/
|
|
if ((info->event == CMD_INSERT) || (info->event == CMD_UPDATE))
|
|
FixNew(info, parsetree);
|
|
|
|
/*--------------------------------------------------
|
|
* Step 3:
|
|
* rewriting due to retrieve rules
|
|
*--------------------------------------------------
|
|
*/
|
|
info->rule_action->rtable = info->rt;
|
|
|
|
/*
|
|
* ProcessRetrieveQuery(info->rule_action, info->rt,
|
|
* &orig_instead_flag, TRUE);
|
|
*/
|
|
|
|
/*--------------------------------------------------
|
|
* Step 4
|
|
* Simplify? hey, no algorithm for simplification... let
|
|
* the planner do it.
|
|
*--------------------------------------------------
|
|
*/
|
|
results = lappend(results, info->rule_action);
|
|
|
|
pfree(info);
|
|
}
|
|
|
|
/* ----------
|
|
* If this was an unqualified instead rule,
|
|
* throw away an eventually saved 'default' parsetree
|
|
* ----------
|
|
*/
|
|
if (event_qual == NULL && *instead_flag)
|
|
*qual_products = NIL;
|
|
}
|
|
return results;
|
|
}
|
|
|
|
|
|
|
|
static List *
|
|
RewriteQuery(Query *parsetree, bool *instead_flag, List **qual_products)
|
|
{
|
|
CmdType event;
|
|
List *product_queries = NIL;
|
|
int result_relation = 0;
|
|
RangeTblEntry *rt_entry;
|
|
Relation rt_entry_relation = NULL;
|
|
RuleLock *rt_entry_locks = NULL;
|
|
|
|
Assert(parsetree != NULL);
|
|
|
|
event = parsetree->commandType;
|
|
|
|
/*
|
|
* SELECT rules are handled later when we have all the queries that
|
|
* should get executed
|
|
*/
|
|
if (event == CMD_SELECT)
|
|
return NIL;
|
|
|
|
/*
|
|
* Utilities aren't rewritten at all - why is this here?
|
|
*/
|
|
if (event == CMD_UTILITY)
|
|
return NIL;
|
|
|
|
/*
|
|
* the statement is an update, insert or delete - fire rules on it.
|
|
*/
|
|
result_relation = parsetree->resultRelation;
|
|
rt_entry = rt_fetch(result_relation, parsetree->rtable);
|
|
rt_entry_relation = heap_openr(rt_entry->relname, AccessShareLock);
|
|
rt_entry_locks = rt_entry_relation->rd_rules;
|
|
|
|
if (rt_entry_locks != NULL)
|
|
{
|
|
List *locks = matchLocks(event, rt_entry_locks,
|
|
result_relation, parsetree);
|
|
|
|
product_queries = fireRules(parsetree,
|
|
result_relation,
|
|
event,
|
|
instead_flag,
|
|
locks,
|
|
qual_products);
|
|
}
|
|
|
|
heap_close(rt_entry_relation, AccessShareLock);
|
|
|
|
return product_queries;
|
|
}
|
|
|
|
|
|
/*
|
|
* to avoid infinite recursion, we restrict the number of times a query
|
|
* can be rewritten. Detecting cycles is left for the reader as an exercise.
|
|
*/
|
|
#ifndef REWRITE_INVOKE_MAX
|
|
#define REWRITE_INVOKE_MAX 10
|
|
#endif
|
|
|
|
static int numQueryRewriteInvoked = 0;
|
|
|
|
/*
|
|
* deepRewriteQuery -
|
|
* rewrites the query and apply the rules again on the queries rewritten
|
|
*/
|
|
static List *
|
|
deepRewriteQuery(Query *parsetree)
|
|
{
|
|
List *n;
|
|
List *rewritten = NIL;
|
|
List *result = NIL;
|
|
bool instead;
|
|
List *qual_products = NIL;
|
|
|
|
if (++numQueryRewriteInvoked > REWRITE_INVOKE_MAX)
|
|
{
|
|
elog(ERROR, "query rewritten %d times, may contain cycles",
|
|
numQueryRewriteInvoked - 1);
|
|
}
|
|
|
|
instead = FALSE;
|
|
result = RewriteQuery(parsetree, &instead, &qual_products);
|
|
|
|
foreach(n, result)
|
|
{
|
|
Query *pt = lfirst(n);
|
|
List *newstuff = NIL;
|
|
|
|
newstuff = deepRewriteQuery(pt);
|
|
if (newstuff != NIL)
|
|
rewritten = nconc(rewritten, newstuff);
|
|
}
|
|
|
|
/* ----------
|
|
* qual_products are the original query with the negated
|
|
* rule qualification of an instead rule
|
|
* ----------
|
|
*/
|
|
if (qual_products != NIL)
|
|
rewritten = nconc(rewritten, qual_products);
|
|
|
|
/* ----------
|
|
* The original query is appended last if not instead
|
|
* because update and delete rule actions might not do
|
|
* anything if they are invoked after the update or
|
|
* delete is performed. The command counter increment
|
|
* between the query execution makes the deleted (and
|
|
* maybe the updated) tuples disappear so the scans
|
|
* for them in the rule actions cannot find them.
|
|
* ----------
|
|
*/
|
|
if (!instead)
|
|
rewritten = lappend(rewritten, parsetree);
|
|
|
|
return rewritten;
|
|
}
|
|
|
|
|
|
/*
|
|
* QueryOneRewrite -
|
|
* rewrite one query
|
|
*/
|
|
static List *
|
|
QueryRewriteOne(Query *parsetree)
|
|
{
|
|
numQueryRewriteInvoked = 0;
|
|
|
|
/*
|
|
* take a deep breath and apply all the rewrite rules - ay
|
|
*/
|
|
return deepRewriteQuery(parsetree);
|
|
}
|
|
|
|
|
|
/*
|
|
* BasicQueryRewrite -
|
|
* rewrite one query via query rewrite system, possibly returning 0
|
|
* or many queries
|
|
*/
|
|
static List *
|
|
BasicQueryRewrite(Query *parsetree)
|
|
{
|
|
List *querylist;
|
|
List *results = NIL;
|
|
List *l;
|
|
Query *query;
|
|
|
|
/*
|
|
* Step 1
|
|
*
|
|
* Apply all non-SELECT rules possibly getting 0 or many queries
|
|
*/
|
|
querylist = QueryRewriteOne(parsetree);
|
|
|
|
/*
|
|
* Step 2
|
|
*
|
|
* Apply all the RIR rules on each query
|
|
*/
|
|
foreach(l, querylist)
|
|
{
|
|
query = fireRIRrules((Query *) lfirst(l));
|
|
|
|
/*
|
|
* If the query was marked having aggregates, check if this is
|
|
* still true after rewriting. Ditto for sublinks. Note there
|
|
* should be no aggs in the qual at this point.
|
|
*/
|
|
if (query->hasAggs)
|
|
{
|
|
query->hasAggs =
|
|
checkExprHasAggs((Node *) (query->targetList)) ||
|
|
checkExprHasAggs((Node *) (query->havingQual));
|
|
if (checkExprHasAggs((Node *) (query->qual)))
|
|
elog(ERROR, "BasicQueryRewrite: failed to remove aggs from qual");
|
|
}
|
|
if (query->hasSubLinks)
|
|
query->hasSubLinks =
|
|
checkExprHasSubLink((Node *) (query->targetList)) ||
|
|
checkExprHasSubLink((Node *) (query->qual)) ||
|
|
checkExprHasSubLink((Node *) (query->havingQual));
|
|
results = lappend(results, query);
|
|
}
|
|
|
|
return results;
|
|
}
|
|
|
|
/*
|
|
* QueryRewrite -
|
|
* Primary entry point to the query rewriter.
|
|
* Rewrite one query via query rewrite system, possibly returning 0
|
|
* or many queries.
|
|
*
|
|
* NOTE: The code in QueryRewrite was formerly in pg_parse_and_plan(), and was
|
|
* moved here so that it would be invoked during EXPLAIN. The division of
|
|
* labor between this routine and BasicQueryRewrite is not obviously correct
|
|
* ... at least not to me ... tgl 5/99.
|
|
*/
|
|
List *
|
|
QueryRewrite(Query *parsetree)
|
|
{
|
|
List *rewritten,
|
|
*rewritten_item;
|
|
|
|
/*
|
|
* Rewrite Union, Intersect and Except Queries to normal Union Queries
|
|
* using IN and NOT IN subselects
|
|
*/
|
|
if (parsetree->intersectClause)
|
|
parsetree = Except_Intersect_Rewrite(parsetree);
|
|
|
|
/* Rewrite basic queries (retrieve, append, delete, replace) */
|
|
rewritten = BasicQueryRewrite(parsetree);
|
|
|
|
/*
|
|
* Rewrite the UNIONS.
|
|
*/
|
|
foreach(rewritten_item, rewritten)
|
|
{
|
|
Query *qry = (Query *) lfirst(rewritten_item);
|
|
List *union_result = NIL;
|
|
List *union_item;
|
|
|
|
foreach(union_item, qry->unionClause)
|
|
{
|
|
union_result = nconc(union_result,
|
|
BasicQueryRewrite((Query *) lfirst(union_item)));
|
|
}
|
|
qry->unionClause = union_result;
|
|
}
|
|
|
|
return rewritten;
|
|
}
|
|
|
|
/* This function takes two targetlists as arguments and checks if the
|
|
* targetlists are compatible (i.e. both select for the same number of
|
|
* attributes and the types are compatible */
|
|
static void
|
|
check_targetlists_are_compatible(List *prev_target, List *current_target)
|
|
{
|
|
List *tl;
|
|
int prev_len = 0,
|
|
next_len = 0;
|
|
|
|
foreach(tl, prev_target)
|
|
if (!((TargetEntry *) lfirst(tl))->resdom->resjunk)
|
|
prev_len++;
|
|
|
|
foreach(tl, current_target)
|
|
if (!((TargetEntry *) lfirst(tl))->resdom->resjunk)
|
|
next_len++;
|
|
|
|
if (prev_len != next_len)
|
|
elog(ERROR, "Each UNION | EXCEPT | INTERSECT query must have the same number of columns.");
|
|
|
|
foreach(tl, current_target)
|
|
{
|
|
TargetEntry *next_tle = (TargetEntry *) lfirst(tl);
|
|
TargetEntry *prev_tle;
|
|
Oid itype;
|
|
Oid otype;
|
|
|
|
if (next_tle->resdom->resjunk)
|
|
continue;
|
|
|
|
/* This loop must find an entry, since we counted them above. */
|
|
do
|
|
{
|
|
prev_tle = (TargetEntry *) lfirst(prev_target);
|
|
prev_target = lnext(prev_target);
|
|
} while (prev_tle->resdom->resjunk);
|
|
|
|
itype = next_tle->resdom->restype;
|
|
otype = prev_tle->resdom->restype;
|
|
|
|
/* one or both is a NULL column? then don't convert... */
|
|
if (otype == InvalidOid)
|
|
{
|
|
/* propagate a known type forward, if available */
|
|
if (itype != InvalidOid)
|
|
prev_tle->resdom->restype = itype;
|
|
#ifdef NOT_USED
|
|
else
|
|
{
|
|
prev_tle->resdom->restype = UNKNOWNOID;
|
|
next_tle->resdom->restype = UNKNOWNOID;
|
|
}
|
|
#endif
|
|
}
|
|
else if (itype == InvalidOid)
|
|
{
|
|
}
|
|
/* they don't match in type? then convert... */
|
|
else if (itype != otype)
|
|
{
|
|
Node *expr;
|
|
|
|
expr = next_tle->expr;
|
|
expr = CoerceTargetExpr(NULL, expr, itype, otype, -1);
|
|
if (expr == NULL)
|
|
{
|
|
elog(ERROR, "Unable to transform %s to %s"
|
|
"\n\tEach UNION | EXCEPT | INTERSECT clause must have compatible target types",
|
|
typeidTypeName(itype),
|
|
typeidTypeName(otype));
|
|
}
|
|
next_tle->expr = expr;
|
|
next_tle->resdom->restype = otype;
|
|
}
|
|
|
|
/* both are UNKNOWN? then evaluate as text... */
|
|
else if (itype == UNKNOWNOID)
|
|
{
|
|
next_tle->resdom->restype = TEXTOID;
|
|
prev_tle->resdom->restype = TEXTOID;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Rewrites UNION INTERSECT and EXCEPT queries to semantiacally equivalent
|
|
* queries that use IN and NOT IN subselects.
|
|
*
|
|
* The operator tree is attached to 'intersectClause' (see rule
|
|
* 'SelectStmt' in gram.y) of the 'parsetree' given as an
|
|
* argument. First we remember some clauses (the sortClause, the
|
|
* distinctClause etc.) Then we translate the operator tree to DNF
|
|
* (disjunctive normal form) by 'cnfify'. (Note that 'cnfify' produces
|
|
* CNF but as we exchanged ANDs with ORs in function A_Expr_to_Expr()
|
|
* earlier we get DNF after exchanging ANDs and ORs again in the
|
|
* result.) Now we create a new query by evaluating the new operator
|
|
* tree which is in DNF now. For every AND we create an entry in the
|
|
* union list and for every OR we create an IN subselect. (NOT IN
|
|
* subselects are created for OR NOT nodes). The first entry of the
|
|
* union list is handed back but before that the remembered clauses
|
|
* (sortClause etc) are attached to the new top Node (Note that the
|
|
* new top Node can differ from the parsetree given as argument because of
|
|
* the translation to DNF. That's why we have to remember the sortClause
|
|
* and so on!) */
|
|
static Query *
|
|
Except_Intersect_Rewrite(Query *parsetree)
|
|
{
|
|
|
|
SubLink *n;
|
|
Query *result,
|
|
*intersect_node;
|
|
List *elist,
|
|
*intersect_list = NIL,
|
|
*intersect,
|
|
*intersectClause;
|
|
List *union_list = NIL,
|
|
*sortClause,
|
|
*distinctClause;
|
|
List *left_expr,
|
|
*resnames = NIL;
|
|
char *op,
|
|
*into;
|
|
bool isBinary,
|
|
isPortal,
|
|
isTemp;
|
|
Node *limitOffset,
|
|
*limitCount;
|
|
CmdType commandType = CMD_SELECT;
|
|
RangeTblEntry *rtable_insert = NULL;
|
|
List *prev_target = NIL;
|
|
|
|
/*
|
|
* Remember the Resnames of the given parsetree's targetlist (these
|
|
* are the resnames of the first Select Statement of the query
|
|
* formulated by the user and he wants the columns named by these
|
|
* strings. The transformation to DNF can cause another Select
|
|
* Statment to be the top one which uses other names for its columns.
|
|
* Therefore we remember the original names and attach them to the
|
|
* targetlist of the new topmost Node at the end of this function
|
|
*/
|
|
foreach(elist, parsetree->targetList)
|
|
{
|
|
TargetEntry *tent = (TargetEntry *) lfirst(elist);
|
|
|
|
if (! tent->resdom->resjunk)
|
|
resnames = lappend(resnames, tent->resdom->resname);
|
|
}
|
|
|
|
/*
|
|
* If the Statement is an INSERT INTO ... (SELECT...) statement using
|
|
* UNIONs, INTERSECTs or EXCEPTs and the transformation to DNF makes
|
|
* another Node to the top node we have to transform the new top node
|
|
* to an INSERT node and the original INSERT node to a SELECT node
|
|
*/
|
|
if (parsetree->commandType == CMD_INSERT)
|
|
{
|
|
|
|
/*
|
|
* The result relation ( = the one to insert into) has to be
|
|
* attached to the rtable list of the new top node
|
|
*/
|
|
rtable_insert = rt_fetch(parsetree->resultRelation, parsetree->rtable);
|
|
|
|
parsetree->commandType = CMD_SELECT;
|
|
commandType = CMD_INSERT;
|
|
parsetree->resultRelation = 0;
|
|
}
|
|
|
|
/*
|
|
* Save some items, to be able to attach them to the resulting top
|
|
* node at the end of the function
|
|
*/
|
|
sortClause = parsetree->sortClause;
|
|
distinctClause = parsetree->distinctClause;
|
|
into = parsetree->into;
|
|
isBinary = parsetree->isBinary;
|
|
isPortal = parsetree->isPortal;
|
|
isTemp = parsetree->isTemp;
|
|
limitOffset = parsetree->limitOffset;
|
|
limitCount = parsetree->limitCount;
|
|
|
|
/*
|
|
* The operator tree attached to parsetree->intersectClause is still
|
|
* 'raw' ( = the leaf nodes are still SelectStmt nodes instead of
|
|
* Query nodes) So step through the tree and transform the nodes using
|
|
* parse_analyze().
|
|
*
|
|
* The parsetree (given as an argument to Except_Intersect_Rewrite()) has
|
|
* already been transformed and transforming it again would cause
|
|
* troubles. So we give the 'raw' version (of the cooked parsetree)
|
|
* to the function to prevent an additional transformation. Instead we
|
|
* hand back the 'cooked' version also given as an argument to
|
|
* intersect_tree_analyze()
|
|
*/
|
|
intersectClause =
|
|
(List *) intersect_tree_analyze((Node *) parsetree->intersectClause,
|
|
(Node *) lfirst(parsetree->unionClause),
|
|
(Node *) parsetree);
|
|
|
|
/* intersectClause is no longer needed so set it to NIL */
|
|
parsetree->intersectClause = NIL;
|
|
|
|
/*
|
|
* unionClause will be needed later on but the list it delivered is no
|
|
* longer needed, so set it to NIL
|
|
*/
|
|
parsetree->unionClause = NIL;
|
|
|
|
/*
|
|
* Transform the operator tree to DNF (remember ANDs and ORs have been
|
|
* exchanged, that's why we get DNF by using cnfify)
|
|
*
|
|
* After the call, explicit ANDs are removed and all AND operands are
|
|
* simply items in the intersectClause list
|
|
*/
|
|
intersectClause = cnfify((Expr *) intersectClause, true);
|
|
|
|
/*
|
|
* For every entry of the intersectClause list we generate one entry
|
|
* in the union_list
|
|
*/
|
|
foreach(intersect, intersectClause)
|
|
{
|
|
|
|
/*
|
|
* for every OR we create an IN subselect and for every OR NOT we
|
|
* create a NOT IN subselect, so first extract all the Select
|
|
* Query nodes from the tree (that contains only OR or OR NOTs any
|
|
* more because we did a transformation to DNF
|
|
*
|
|
* There must be at least one node that is not negated (i.e. just OR
|
|
* and not OR NOT) and this node will be the first in the list
|
|
* returned
|
|
*/
|
|
intersect_list = NIL;
|
|
create_intersect_list((Node *) lfirst(intersect), &intersect_list);
|
|
|
|
/*
|
|
* This one will become the Select Query node, all other nodes are
|
|
* transformed into subselects under this node!
|
|
*/
|
|
intersect_node = (Query *) lfirst(intersect_list);
|
|
intersect_list = lnext(intersect_list);
|
|
|
|
/*
|
|
* Check if all Select Statements use the same number of
|
|
* attributes and if all corresponding attributes are of the same
|
|
* type
|
|
*/
|
|
if (prev_target)
|
|
check_targetlists_are_compatible(prev_target, intersect_node->targetList);
|
|
prev_target = intersect_node->targetList;
|
|
|
|
/*
|
|
* Transform all nodes remaining into subselects and add them to
|
|
* the qualifications of the Select Query node
|
|
*/
|
|
while (intersect_list != NIL)
|
|
{
|
|
|
|
n = makeNode(SubLink);
|
|
|
|
/* Here we got an OR so transform it to an IN subselect */
|
|
if (IsA(lfirst(intersect_list), Query))
|
|
{
|
|
|
|
/*
|
|
* Check if all Select Statements use the same number of
|
|
* attributes and if all corresponding attributes are of
|
|
* the same type
|
|
*/
|
|
check_targetlists_are_compatible(prev_target,
|
|
((Query *) lfirst(intersect_list))->targetList);
|
|
|
|
n->subselect = lfirst(intersect_list);
|
|
op = "=";
|
|
n->subLinkType = ANY_SUBLINK;
|
|
n->useor = false;
|
|
}
|
|
|
|
/*
|
|
* Here we got an OR NOT node so transform it to a NOT IN
|
|
* subselect
|
|
*/
|
|
else
|
|
{
|
|
|
|
/*
|
|
* Check if all Select Statements use the same number of
|
|
* attributes and if all corresponding attributes are of
|
|
* the same type
|
|
*/
|
|
check_targetlists_are_compatible(prev_target,
|
|
((Query *) lfirst(((Expr *) lfirst(intersect_list))->args))->targetList);
|
|
|
|
n->subselect = (Node *) lfirst(((Expr *) lfirst(intersect_list))->args);
|
|
op = "<>";
|
|
n->subLinkType = ALL_SUBLINK;
|
|
n->useor = true;
|
|
}
|
|
|
|
/*
|
|
* Prepare the lefthand side of the Sublinks: All the entries
|
|
* of the targetlist must be (IN) or must not be (NOT IN) the
|
|
* subselect
|
|
*/
|
|
n->lefthand = NIL;
|
|
foreach(elist, intersect_node->targetList)
|
|
{
|
|
TargetEntry *tent = (TargetEntry *) lfirst(elist);
|
|
|
|
if (! tent->resdom->resjunk)
|
|
n->lefthand = lappend(n->lefthand, tent->expr);
|
|
}
|
|
|
|
/*
|
|
* Also prepare the list of Opers that must be used for the
|
|
* comparisons (they depend on the specific datatypes
|
|
* involved!)
|
|
*/
|
|
left_expr = n->lefthand;
|
|
n->oper = NIL;
|
|
|
|
foreach(elist, ((Query *) (n->subselect))->targetList)
|
|
{
|
|
TargetEntry *tent = (TargetEntry *) lfirst(elist);
|
|
Node *lexpr;
|
|
Operator optup;
|
|
Form_pg_operator opform;
|
|
Oper *newop;
|
|
|
|
if (tent->resdom->resjunk)
|
|
continue;
|
|
|
|
lexpr = lfirst(left_expr);
|
|
|
|
optup = oper(op,
|
|
exprType(lexpr),
|
|
exprType(tent->expr),
|
|
FALSE);
|
|
opform = (Form_pg_operator) GETSTRUCT(optup);
|
|
|
|
if (opform->oprresult != BOOLOID)
|
|
elog(ERROR, "parser: '%s' must return 'bool' to be used with quantified predicate subquery", op);
|
|
|
|
newop = makeOper(oprid(optup), /* opno */
|
|
InvalidOid, /* opid */
|
|
opform->oprresult);
|
|
|
|
n->oper = lappend(n->oper, newop);
|
|
|
|
left_expr = lnext(left_expr);
|
|
}
|
|
|
|
Assert(left_expr == NIL); /* should have used 'em all */
|
|
|
|
/*
|
|
* If the Select Query node has aggregates in use add all the
|
|
* subselects to the HAVING qual else to the WHERE qual
|
|
*/
|
|
if (intersect_node->hasAggs)
|
|
AddHavingQual(intersect_node, (Node *) n);
|
|
else
|
|
AddQual(intersect_node, (Node *) n);
|
|
|
|
/* Now we got sublinks */
|
|
intersect_node->hasSubLinks = true;
|
|
intersect_list = lnext(intersect_list);
|
|
}
|
|
intersect_node->intersectClause = NIL;
|
|
union_list = lappend(union_list, intersect_node);
|
|
}
|
|
|
|
/* The first entry to union_list is our new top node */
|
|
result = (Query *) lfirst(union_list);
|
|
/* attach the rest to unionClause */
|
|
result->unionClause = lnext(union_list);
|
|
/* Attach all the items remembered in the beginning of the function */
|
|
result->sortClause = sortClause;
|
|
result->distinctClause = distinctClause;
|
|
result->into = into;
|
|
result->isPortal = isPortal;
|
|
result->isBinary = isBinary;
|
|
result->isTemp = isTemp;
|
|
result->limitOffset = limitOffset;
|
|
result->limitCount = limitCount;
|
|
|
|
/*
|
|
* The relation to insert into is attached to the range table of the
|
|
* new top node
|
|
*/
|
|
if (commandType == CMD_INSERT)
|
|
{
|
|
result->rtable = lappend(result->rtable, rtable_insert);
|
|
result->resultRelation = length(result->rtable);
|
|
result->commandType = commandType;
|
|
}
|
|
|
|
/*
|
|
* The resnames of the originally first SelectStatement are attached
|
|
* to the new first SelectStatement
|
|
*/
|
|
foreach(elist, result->targetList)
|
|
{
|
|
TargetEntry *tent = (TargetEntry *) lfirst(elist);
|
|
|
|
if (tent->resdom->resjunk)
|
|
continue;
|
|
|
|
tent->resdom->resname = lfirst(resnames);
|
|
resnames = lnext(resnames);
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/* Create a list of nodes that are either Query nodes of NOT Expr
|
|
* nodes followed by a Query node. The tree given in ptr contains at
|
|
* least one non negated Query node. This node is attached to the
|
|
* beginning of the list */
|
|
|
|
static void
|
|
create_intersect_list(Node *ptr, List **intersect_list)
|
|
{
|
|
List *arg;
|
|
|
|
if (IsA(ptr, Query))
|
|
{
|
|
/* The non negated node is attached at the beginning (lcons) */
|
|
*intersect_list = lcons(ptr, *intersect_list);
|
|
return;
|
|
}
|
|
|
|
if (IsA(ptr, Expr))
|
|
{
|
|
if (((Expr *) ptr)->opType == NOT_EXPR)
|
|
{
|
|
/* negated nodes are appended to the end (lappend) */
|
|
*intersect_list = lappend(*intersect_list, ptr);
|
|
return;
|
|
}
|
|
else
|
|
{
|
|
foreach(arg, ((Expr *) ptr)->args)
|
|
create_intersect_list(lfirst(arg), intersect_list);
|
|
return;
|
|
}
|
|
return;
|
|
}
|
|
}
|
|
|
|
/* The nodes given in 'tree' are still 'raw' so 'cook' them using parse_analyze().
|
|
* The node given in first_select has already been cooked, so don't transform
|
|
* it again but return a pointer to the previously cooked version given in 'parsetree'
|
|
* instead. */
|
|
static Node *
|
|
intersect_tree_analyze(Node *tree, Node *first_select, Node *parsetree)
|
|
{
|
|
Node *result = (Node *) NIL;
|
|
List *arg;
|
|
|
|
if (IsA(tree, SelectStmt))
|
|
{
|
|
|
|
/*
|
|
* If we get to the tree given in first_select return parsetree
|
|
* instead of performing parse_analyze()
|
|
*/
|
|
if (tree == first_select)
|
|
result = parsetree;
|
|
else
|
|
{
|
|
/* transform the 'raw' nodes to 'cooked' Query nodes */
|
|
List *qtree = parse_analyze(lcons(tree, NIL), NULL);
|
|
|
|
result = (Node *) lfirst(qtree);
|
|
}
|
|
}
|
|
|
|
if (IsA(tree, Expr))
|
|
{
|
|
/* Call recursively for every argument of the node */
|
|
foreach(arg, ((Expr *) tree)->args)
|
|
lfirst(arg) = intersect_tree_analyze(lfirst(arg), first_select, parsetree);
|
|
result = tree;
|
|
}
|
|
return result;
|
|
}
|