#include "postgres.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/optimizer.h"
#include "utils/lsyscache.h"

Include dependency graph for prepqual.c:

Functions
static List *	pull_ands (List *andlist)

static List *	pull_ors (List *orlist)

static Expr *	find_duplicate_ors (Expr *qual, bool is_check)

static Expr *	process_duplicate_ors (List *orlist)

Node *	negate_clause (Node *node)

Expr *	canonicalize_qual (Expr *qual, bool is_check)

Function Documentation

◆ canonicalize_qual()

Expr* canonicalize_qual	(	Expr *	qual,
		bool	is_check
	)

Definition at line 293 of file prepqual.c.

 {
     Expr       *newqual;
  
     /* Quick exit for empty qual */
     if (qual == NULL)
         return NULL;
  
     /* This should not be invoked on quals in implicit-AND format */
     Assert(!IsA(qual, List));
  
     /*
      * Pull up redundant subclauses in OR-of-AND trees.  We do this only
      * within the top-level AND/OR structure; there's no point in looking
      * deeper.  Also remove any NULL constants in the top-level structure.
      */
     newqual = find_duplicate_ors(qual, is_check);
  
     return newqual;
 }

References Assert, find_duplicate_ors(), and IsA.

Referenced by ConstraintImpliedByRelConstraint(), convert_EXISTS_to_ANY(), DoCopy(), get_proposed_default_constraint(), get_relation_constraints(), preprocess_expression(), and RelationGetIndexPredicate().

◆ find_duplicate_ors()

static Expr * find_duplicate_ors	(	Expr *	qual,
		bool	is_check
	)

static

Definition at line 406 of file prepqual.c.

 {
     if (is_orclause(qual))
     {
         List       *orlist = NIL;
         ListCell   *temp;
  
         /* Recurse */
         foreach(temp, ((BoolExpr *) qual)->args)
         {
             Expr       *arg = (Expr *) lfirst(temp);
  
             arg = find_duplicate_ors(arg, is_check);
  
             /* Get rid of any constant inputs */
             if (arg && IsA(arg, Const))
             {
                 Const      *carg = (Const *) arg;
  
                 if (is_check)
                 {
                     /* Within OR in CHECK, drop constant FALSE */
                     if (!carg->constisnull && !DatumGetBool(carg->constvalue))
                         continue;
                     /* Constant TRUE or NULL, so OR reduces to TRUE */
                     return (Expr *) makeBoolConst(true, false);
                 }
                 else
                 {
                     /* Within OR in WHERE, drop constant FALSE or NULL */
                     if (carg->constisnull || !DatumGetBool(carg->constvalue))
                         continue;
                     /* Constant TRUE, so OR reduces to TRUE */
                     return arg;
                 }
             }
  
             orlist = lappend(orlist, arg);
         }
  
         /* Flatten any ORs pulled up to just below here */
         orlist = pull_ors(orlist);
  
         /* Now we can look for duplicate ORs */
         return process_duplicate_ors(orlist);
     }
     else if (is_andclause(qual))
     {
         List       *andlist = NIL;
         ListCell   *temp;
  
         /* Recurse */
         foreach(temp, ((BoolExpr *) qual)->args)
         {
             Expr       *arg = (Expr *) lfirst(temp);
  
             arg = find_duplicate_ors(arg, is_check);
  
             /* Get rid of any constant inputs */
             if (arg && IsA(arg, Const))
             {
                 Const      *carg = (Const *) arg;
  
                 if (is_check)
                 {
                     /* Within AND in CHECK, drop constant TRUE or NULL */
                     if (carg->constisnull || DatumGetBool(carg->constvalue))
                         continue;
                     /* Constant FALSE, so AND reduces to FALSE */
                     return arg;
                 }
                 else
                 {
                     /* Within AND in WHERE, drop constant TRUE */
                     if (!carg->constisnull && DatumGetBool(carg->constvalue))
                         continue;
                     /* Constant FALSE or NULL, so AND reduces to FALSE */
                     return (Expr *) makeBoolConst(false, false);
                 }
             }
  
             andlist = lappend(andlist, arg);
         }
  
         /* Flatten any ANDs introduced just below here */
         andlist = pull_ands(andlist);
  
         /* AND of no inputs reduces to TRUE */
         if (andlist == NIL)
             return (Expr *) makeBoolConst(true, false);
  
         /* Single-expression AND just reduces to that expression */
         if (list_length(andlist) == 1)
             return (Expr *) linitial(andlist);
  
         /* Else we still need an AND node */
         return make_andclause(andlist);
     }
     else
         return qual;
 }

References arg, generate_unaccent_rules::args, DatumGetBool(), is_andclause(), is_orclause(), IsA, lappend(), lfirst, linitial, list_length(), make_andclause(), makeBoolConst(), NIL, process_duplicate_ors(), pull_ands(), and pull_ors().

Referenced by canonicalize_qual().

◆ negate_clause()

Node* negate_clause ( Node * node )

Definition at line 73 of file prepqual.c.

 {
     if (node == NULL)           /* should not happen */
         elog(ERROR, "can't negate an empty subexpression");
     switch (nodeTag(node))
     {
         case T_Const:
             {
                 Const      *c = (Const *) node;
  
                 /* NOT NULL is still NULL */
                 if (c->constisnull)
                     return makeBoolConst(false, true);
                 /* otherwise pretty easy */
                 return makeBoolConst(!DatumGetBool(c->constvalue), false);
             }
             break;
         case T_OpExpr:
             {
                 /*
                  * Negate operator if possible: (NOT (< A B)) => (>= A B)
                  */
                 OpExpr     *opexpr = (OpExpr *) node;
                 Oid         negator = get_negator(opexpr->opno);
  
                 if (negator)
                 {
                     OpExpr     *newopexpr = makeNode(OpExpr);
  
                     newopexpr->opno = negator;
                     newopexpr->opfuncid = InvalidOid;
                     newopexpr->opresulttype = opexpr->opresulttype;
                     newopexpr->opretset = opexpr->opretset;
                     newopexpr->opcollid = opexpr->opcollid;
                     newopexpr->inputcollid = opexpr->inputcollid;
                     newopexpr->args = opexpr->args;
                     newopexpr->location = opexpr->location;
                     return (Node *) newopexpr;
                 }
             }
             break;
         case T_ScalarArrayOpExpr:
             {
                 /*
                  * Negate a ScalarArrayOpExpr if its operator has a negator;
                  * for example x = ANY (list) becomes x <> ALL (list)
                  */
                 ScalarArrayOpExpr *saopexpr = (ScalarArrayOpExpr *) node;
                 Oid         negator = get_negator(saopexpr->opno);
  
                 if (negator)
                 {
                     ScalarArrayOpExpr *newopexpr = makeNode(ScalarArrayOpExpr);
  
                     newopexpr->opno = negator;
                     newopexpr->opfuncid = InvalidOid;
                     newopexpr->hashfuncid = InvalidOid;
                     newopexpr->negfuncid = InvalidOid;
                     newopexpr->useOr = !saopexpr->useOr;
                     newopexpr->inputcollid = saopexpr->inputcollid;
                     newopexpr->args = saopexpr->args;
                     newopexpr->location = saopexpr->location;
                     return (Node *) newopexpr;
                 }
             }
             break;
         case T_BoolExpr:
             {
                 BoolExpr   *expr = (BoolExpr *) node;
  
                 switch (expr->boolop)
                 {
                         /*--------------------
                          * Apply DeMorgan's Laws:
                          *      (NOT (AND A B)) => (OR (NOT A) (NOT B))
                          *      (NOT (OR A B))  => (AND (NOT A) (NOT B))
                          * i.e., swap AND for OR and negate each subclause.
                          *
                          * If the input is already AND/OR flat and has no NOT
                          * directly above AND or OR, this transformation preserves
                          * those properties.  For example, if no direct child of
                          * the given AND clause is an AND or a NOT-above-OR, then
                          * the recursive calls of negate_clause() can't return any
                          * OR clauses.  So we needn't call pull_ors() before
                          * building a new OR clause.  Similarly for the OR case.
                          *--------------------
                          */
                     case AND_EXPR:
                         {
                             List       *nargs = NIL;
                             ListCell   *lc;
  
                             foreach(lc, expr->args)
                             {
                                 nargs = lappend(nargs,
                                                 negate_clause(lfirst(lc)));
                             }
                             return (Node *) make_orclause(nargs);
                         }
                         break;
                     case OR_EXPR:
                         {
                             List       *nargs = NIL;
                             ListCell   *lc;
  
                             foreach(lc, expr->args)
                             {
                                 nargs = lappend(nargs,
                                                 negate_clause(lfirst(lc)));
                             }
                             return (Node *) make_andclause(nargs);
                         }
                         break;
                     case NOT_EXPR:
  
                         /*
                          * NOT underneath NOT: they cancel.  We assume the
                          * input is already simplified, so no need to recurse.
                          */
                         return (Node *) linitial(expr->args);
                     default:
                         elog(ERROR, "unrecognized boolop: %d",
                              (int) expr->boolop);
                         break;
                 }
             }
             break;
         case T_NullTest:
             {
                 NullTest   *expr = (NullTest *) node;
  
                 /*
                  * In the rowtype case, the two flavors of NullTest are *not*
                  * logical inverses, so we can't simplify.  But it does work
                  * for scalar datatypes.
                  */
                 if (!expr->argisrow)
                 {
                     NullTest   *newexpr = makeNode(NullTest);
  
                     newexpr->arg = expr->arg;
                     newexpr->nulltesttype = (expr->nulltesttype == IS_NULL ?
                                              IS_NOT_NULL : IS_NULL);
                     newexpr->argisrow = expr->argisrow;
                     newexpr->location = expr->location;
                     return (Node *) newexpr;
                 }
             }
             break;
         case T_BooleanTest:
             {
                 BooleanTest *expr = (BooleanTest *) node;
                 BooleanTest *newexpr = makeNode(BooleanTest);
  
                 newexpr->arg = expr->arg;
                 switch (expr->booltesttype)
                 {
                     case IS_TRUE:
                         newexpr->booltesttype = IS_NOT_TRUE;
                         break;
                     case IS_NOT_TRUE:
                         newexpr->booltesttype = IS_TRUE;
                         break;
                     case IS_FALSE:
                         newexpr->booltesttype = IS_NOT_FALSE;
                         break;
                     case IS_NOT_FALSE:
                         newexpr->booltesttype = IS_FALSE;
                         break;
                     case IS_UNKNOWN:
                         newexpr->booltesttype = IS_NOT_UNKNOWN;
                         break;
                     case IS_NOT_UNKNOWN:
                         newexpr->booltesttype = IS_UNKNOWN;
                         break;
                     default:
                         elog(ERROR, "unrecognized booltesttype: %d",
                              (int) expr->booltesttype);
                         break;
                 }
                 newexpr->location = expr->location;
                 return (Node *) newexpr;
             }
             break;
         default:
             /* else fall through */
             break;
     }
  
     /*
      * Otherwise we don't know how to simplify this, so just tack on an
      * explicit NOT node.
      */
     return (Node *) make_notclause((Expr *) node);
 }

References AND_EXPR, NullTest::arg, BooleanTest::arg, OpExpr::args, ScalarArrayOpExpr::args, BoolExpr::args, BoolExpr::boolop, BooleanTest::booltesttype, DatumGetBool(), elog, ERROR, get_negator(), InvalidOid, IS_FALSE, IS_NOT_FALSE, IS_NOT_NULL, IS_NOT_TRUE, IS_NOT_UNKNOWN, IS_NULL, IS_TRUE, IS_UNKNOWN, lappend(), lfirst, linitial, OpExpr::location, ScalarArrayOpExpr::location, NullTest::location, BooleanTest::location, make_andclause(), make_notclause(), make_orclause(), makeBoolConst(), makeNode, NIL, nodeTag, NOT_EXPR, NullTest::nulltesttype, OpExpr::opno, ScalarArrayOpExpr::opno, OR_EXPR, and ScalarArrayOpExpr::useOr.

Referenced by eval_const_expressions_mutator(), match_boolean_partition_clause(), and simplify_boolean_equality().

◆ process_duplicate_ors()

static Expr * process_duplicate_ors ( List * orlist )

static

Definition at line 517 of file prepqual.c.

 {
     List       *reference = NIL;
     int         num_subclauses = 0;
     List       *winners;
     List       *neworlist;
     ListCell   *temp;
  
     /* OR of no inputs reduces to FALSE */
     if (orlist == NIL)
         return (Expr *) makeBoolConst(false, false);
  
     /* Single-expression OR just reduces to that expression */
     if (list_length(orlist) == 1)
         return (Expr *) linitial(orlist);
  
     /*
      * Choose the shortest AND clause as the reference list --- obviously, any
      * subclause not in this clause isn't in all the clauses. If we find a
      * clause that's not an AND, we can treat it as a one-element AND clause,
      * which necessarily wins as shortest.
      */
     foreach(temp, orlist)
     {
         Expr       *clause = (Expr *) lfirst(temp);
  
         if (is_andclause(clause))
         {
             List       *subclauses = ((BoolExpr *) clause)->args;
             int         nclauses = list_length(subclauses);
  
             if (reference == NIL || nclauses < num_subclauses)
             {
                 reference = subclauses;
                 num_subclauses = nclauses;
             }
         }
         else
         {
             reference = list_make1(clause);
             break;
         }
     }
  
     /*
      * Just in case, eliminate any duplicates in the reference list.
      */
     reference = list_union(NIL, reference);
  
     /*
      * Check each element of the reference list to see if it's in all the OR
      * clauses.  Build a new list of winning clauses.
      */
     winners = NIL;
     foreach(temp, reference)
     {
         Expr       *refclause = (Expr *) lfirst(temp);
         bool        win = true;
         ListCell   *temp2;
  
         foreach(temp2, orlist)
         {
             Expr       *clause = (Expr *) lfirst(temp2);
  
             if (is_andclause(clause))
             {
                 if (!list_member(((BoolExpr *) clause)->args, refclause))
                 {
                     win = false;
                     break;
                 }
             }
             else
             {
                 if (!equal(refclause, clause))
                 {
                     win = false;
                     break;
                 }
             }
         }
  
         if (win)
             winners = lappend(winners, refclause);
     }
  
     /*
      * If no winners, we can't transform the OR
      */
     if (winners == NIL)
         return make_orclause(orlist);
  
     /*
      * Generate new OR list consisting of the remaining sub-clauses.
      *
      * If any clause degenerates to empty, then we have a situation like (A
      * AND B) OR (A), which can be reduced to just A --- that is, the
      * additional conditions in other arms of the OR are irrelevant.
      *
      * Note that because we use list_difference, any multiple occurrences of a
      * winning clause in an AND sub-clause will be removed automatically.
      */
     neworlist = NIL;
     foreach(temp, orlist)
     {
         Expr       *clause = (Expr *) lfirst(temp);
  
         if (is_andclause(clause))
         {
             List       *subclauses = ((BoolExpr *) clause)->args;
  
             subclauses = list_difference(subclauses, winners);
             if (subclauses != NIL)
             {
                 if (list_length(subclauses) == 1)
                     neworlist = lappend(neworlist, linitial(subclauses));
                 else
                     neworlist = lappend(neworlist, make_andclause(subclauses));
             }
             else
             {
                 neworlist = NIL;    /* degenerate case, see above */
                 break;
             }
         }
         else
         {
             if (!list_member(winners, clause))
                 neworlist = lappend(neworlist, clause);
             else
             {
                 neworlist = NIL;    /* degenerate case, see above */
                 break;
             }
         }
     }
  
     /*
      * Append reduced OR to the winners list, if it's not degenerate, handling
      * the special case of one element correctly (can that really happen?).
      * Also be careful to maintain AND/OR flatness in case we pulled up a
      * sub-sub-OR-clause.
      */
     if (neworlist != NIL)
     {
         if (list_length(neworlist) == 1)
             winners = lappend(winners, linitial(neworlist));
         else
             winners = lappend(winners, make_orclause(pull_ors(neworlist)));
     }
  
     /*
      * And return the constructed AND clause, again being wary of a single
      * element and AND/OR flatness.
      */
     if (list_length(winners) == 1)
         return (Expr *) linitial(winners);
     else
         return make_andclause(pull_ands(winners));
 }

References equal(), is_andclause(), lappend(), lfirst, linitial, list_difference(), list_length(), list_make1, list_member(), list_union(), make_andclause(), make_orclause(), makeBoolConst(), NIL, pull_ands(), and pull_ors().

Referenced by find_duplicate_ors().

◆ pull_ands()

static List * pull_ands ( List * andlist )

static

Definition at line 323 of file prepqual.c.

 {
     List       *out_list = NIL;
     ListCell   *arg;
  
     foreach(arg, andlist)
     {
         Node       *subexpr = (Node *) lfirst(arg);
  
         if (is_andclause(subexpr))
             out_list = list_concat(out_list,
                                    pull_ands(((BoolExpr *) subexpr)->args));
         else
             out_list = lappend(out_list, subexpr);
     }
     return out_list;
 }

References arg, generate_unaccent_rules::args, is_andclause(), lappend(), lfirst, list_concat(), and NIL.

Referenced by find_duplicate_ors(), and process_duplicate_ors().

◆ pull_ors()

static List * pull_ors ( List * orlist )

static

Definition at line 349 of file prepqual.c.

 {
     List       *out_list = NIL;
     ListCell   *arg;
  
     foreach(arg, orlist)
     {
         Node       *subexpr = (Node *) lfirst(arg);
  
         if (is_orclause(subexpr))
             out_list = list_concat(out_list,
                                    pull_ors(((BoolExpr *) subexpr)->args));
         else
             out_list = lappend(out_list, subexpr);
     }
     return out_list;
 }

References arg, generate_unaccent_rules::args, is_orclause(), lappend(), lfirst, list_concat(), and NIL.

Referenced by find_duplicate_ors(), and process_duplicate_ors().

Functions

Function Documentation

◆ canonicalize_qual()

◆ find_duplicate_ors()

◆ negate_clause()

◆ process_duplicate_ors()

◆ pull_ands()

◆ pull_ors()