/*------------------------------------------------------------------------- * * parse_clause.c * handle clauses in parser * * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.170 2008/06/19 00:46:05 alvherre Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" #include "access/heapam.h" #include "catalog/heap.h" #include "catalog/pg_type.h" #include "commands/defrem.h" #include "nodes/makefuncs.h" #include "optimizer/clauses.h" #include "optimizer/tlist.h" #include "optimizer/var.h" #include "parser/analyze.h" #include "parser/parsetree.h" #include "parser/parse_clause.h" #include "parser/parse_coerce.h" #include "parser/parse_expr.h" #include "parser/parse_oper.h" #include "parser/parse_relation.h" #include "parser/parse_target.h" #include "rewrite/rewriteManip.h" #include "utils/guc.h" #include "utils/lsyscache.h" #include "utils/rel.h" #define ORDER_CLAUSE 0 #define GROUP_CLAUSE 1 #define DISTINCT_ON_CLAUSE 2 static char *clauseText[] = {"ORDER BY", "GROUP BY", "DISTINCT ON"}; static void extractRemainingColumns(List *common_colnames, List *src_colnames, List *src_colvars, List **res_colnames, List **res_colvars); static Node *transformJoinUsingClause(ParseState *pstate, List *leftVars, List *rightVars); static Node *transformJoinOnClause(ParseState *pstate, JoinExpr *j, RangeTblEntry *l_rte, RangeTblEntry *r_rte, List *relnamespace, Relids containedRels); static RangeTblEntry *transformTableEntry(ParseState *pstate, RangeVar *r); static RangeTblEntry *transformRangeSubselect(ParseState *pstate, RangeSubselect *r); static RangeTblEntry *transformRangeFunction(ParseState *pstate, RangeFunction *r); static Node *transformFromClauseItem(ParseState *pstate, Node *n, RangeTblEntry **top_rte, int *top_rti, List **relnamespace, Relids *containedRels); static Node *buildMergedJoinVar(ParseState *pstate, JoinType jointype, Var *l_colvar, Var *r_colvar); static TargetEntry *findTargetlistEntry(ParseState *pstate, Node *node, List **tlist, int clause); /* * transformFromClause - * Process the FROM clause and add items to the query's range table, * joinlist, and namespaces. * * Note: we assume that pstate's p_rtable, p_joinlist, p_relnamespace, and * p_varnamespace lists were initialized to NIL when the pstate was created. * We will add onto any entries already present --- this is needed for rule * processing, as well as for UPDATE and DELETE. * * The range table may grow still further when we transform the expressions * in the query's quals and target list. (This is possible because in * POSTQUEL, we allowed references to relations not specified in the * from-clause. PostgreSQL keeps this extension to standard SQL.) */ void transformFromClause(ParseState *pstate, List *frmList) { ListCell *fl; /* * The grammar will have produced a list of RangeVars, RangeSubselects, * RangeFunctions, and/or JoinExprs. Transform each one (possibly adding * entries to the rtable), check for duplicate refnames, and then add it * to the joinlist and namespaces. */ foreach(fl, frmList) { Node *n = lfirst(fl); RangeTblEntry *rte; int rtindex; List *relnamespace; Relids containedRels; n = transformFromClauseItem(pstate, n, &rte, &rtindex, &relnamespace, &containedRels); checkNameSpaceConflicts(pstate, pstate->p_relnamespace, relnamespace); pstate->p_joinlist = lappend(pstate->p_joinlist, n); pstate->p_relnamespace = list_concat(pstate->p_relnamespace, relnamespace); pstate->p_varnamespace = lappend(pstate->p_varnamespace, rte); bms_free(containedRels); } } /* * setTargetTable * Add the target relation of INSERT/UPDATE/DELETE to the range table, * and make the special links to it in the ParseState. * * We also open the target relation and acquire a write lock on it. * This must be done before processing the FROM list, in case the target * is also mentioned as a source relation --- we want to be sure to grab * the write lock before any read lock. * * If alsoSource is true, add the target to the query's joinlist and * namespace. For INSERT, we don't want the target to be joined to; * it's a destination of tuples, not a source. For UPDATE/DELETE, * we do need to scan or join the target. (NOTE: we do not bother * to check for namespace conflict; we assume that the namespace was * initially empty in these cases.) * * Finally, we mark the relation as requiring the permissions specified * by requiredPerms. * * Returns the rangetable index of the target relation. */ int setTargetTable(ParseState *pstate, RangeVar *relation, bool inh, bool alsoSource, AclMode requiredPerms) { RangeTblEntry *rte; int rtindex; /* Close old target; this could only happen for multi-action rules */ if (pstate->p_target_relation != NULL) heap_close(pstate->p_target_relation, NoLock); /* * Open target rel and grab suitable lock (which we will hold till end of * transaction). * * free_parsestate() will eventually do the corresponding heap_close(), * but *not* release the lock. */ pstate->p_target_relation = heap_openrv(relation, RowExclusiveLock); /* * Now build an RTE. */ rte = addRangeTableEntryForRelation(pstate, pstate->p_target_relation, relation->alias, inh, false); pstate->p_target_rangetblentry = rte; /* assume new rte is at end */ rtindex = list_length(pstate->p_rtable); Assert(rte == rt_fetch(rtindex, pstate->p_rtable)); /* * Override addRangeTableEntry's default ACL_SELECT permissions check, and * instead mark target table as requiring exactly the specified * permissions. * * If we find an explicit reference to the rel later during parse * analysis, we will add the ACL_SELECT bit back again; see * scanRTEForColumn (for simple field references), ExpandColumnRefStar * (for foo.*) and ExpandAllTables (for *). */ rte->requiredPerms = requiredPerms; /* * If UPDATE/DELETE, add table to joinlist and namespaces. */ if (alsoSource) addRTEtoQuery(pstate, rte, true, true, true); return rtindex; } /* * Simplify InhOption (yes/no/default) into boolean yes/no. * * The reason we do things this way is that we don't want to examine the * SQL_inheritance option flag until parse_analyze() is run. Otherwise, * we'd do the wrong thing with query strings that intermix SET commands * with queries. */ bool interpretInhOption(InhOption inhOpt) { switch (inhOpt) { case INH_NO: return false; case INH_YES: return true; case INH_DEFAULT: return SQL_inheritance; } elog(ERROR, "bogus InhOption value: %d", inhOpt); return false; /* keep compiler quiet */ } /* * Given a relation-options list (of DefElems), return true iff the specified * table/result set should be created with OIDs. This needs to be done after * parsing the query string because the return value can depend upon the * default_with_oids GUC var. */ bool interpretOidsOption(List *defList) { ListCell *cell; /* Scan list to see if OIDS was included */ foreach(cell, defList) { DefElem *def = (DefElem *) lfirst(cell); if (pg_strcasecmp(def->defname, "oids") == 0) return defGetBoolean(def); } /* OIDS option was not specified, so use default. */ return default_with_oids; } /* * Extract all not-in-common columns from column lists of a source table */ static void extractRemainingColumns(List *common_colnames, List *src_colnames, List *src_colvars, List **res_colnames, List **res_colvars) { List *new_colnames = NIL; List *new_colvars = NIL; ListCell *lnames, *lvars; Assert(list_length(src_colnames) == list_length(src_colvars)); forboth(lnames, src_colnames, lvars, src_colvars) { char *colname = strVal(lfirst(lnames)); bool match = false; ListCell *cnames; foreach(cnames, common_colnames) { char *ccolname = strVal(lfirst(cnames)); if (strcmp(colname, ccolname) == 0) { match = true; break; } } if (!match) { new_colnames = lappend(new_colnames, lfirst(lnames)); new_colvars = lappend(new_colvars, lfirst(lvars)); } } *res_colnames = new_colnames; *res_colvars = new_colvars; } /* transformJoinUsingClause() * Build a complete ON clause from a partially-transformed USING list. * We are given lists of nodes representing left and right match columns. * Result is a transformed qualification expression. */ static Node * transformJoinUsingClause(ParseState *pstate, List *leftVars, List *rightVars) { Node *result = NULL; ListCell *lvars, *rvars; /* * We cheat a little bit here by building an untransformed operator tree * whose leaves are the already-transformed Vars. This is OK because * transformExpr() won't complain about already-transformed subnodes. */ forboth(lvars, leftVars, rvars, rightVars) { Node *lvar = (Node *) lfirst(lvars); Node *rvar = (Node *) lfirst(rvars); A_Expr *e; e = makeSimpleA_Expr(AEXPR_OP, "=", copyObject(lvar), copyObject(rvar), -1); if (result == NULL) result = (Node *) e; else { A_Expr *a; a = makeA_Expr(AEXPR_AND, NIL, result, (Node *) e, -1); result = (Node *) a; } } /* * Since the references are already Vars, and are certainly from the input * relations, we don't have to go through the same pushups that * transformJoinOnClause() does. Just invoke transformExpr() to fix up * the operators, and we're done. */ result = transformExpr(pstate, result); result = coerce_to_boolean(pstate, result, "JOIN/USING"); return result; } /* transformJoinOnClause() * Transform the qual conditions for JOIN/ON. * Result is a transformed qualification expression. */ static Node * transformJoinOnClause(ParseState *pstate, JoinExpr *j, RangeTblEntry *l_rte, RangeTblEntry *r_rte, List *relnamespace, Relids containedRels) { Node *result; List *save_relnamespace; List *save_varnamespace; Relids clause_varnos; int varno; /* * This is a tad tricky, for two reasons. First, the namespace that the * join expression should see is just the two subtrees of the JOIN plus * any outer references from upper pstate levels. So, temporarily set * this pstate's namespace accordingly. (We need not check for refname * conflicts, because transformFromClauseItem() already did.) NOTE: this * code is OK only because the ON clause can't legally alter the namespace * by causing implicit relation refs to be added. */ save_relnamespace = pstate->p_relnamespace; save_varnamespace = pstate->p_varnamespace; pstate->p_relnamespace = relnamespace; pstate->p_varnamespace = list_make2(l_rte, r_rte); result = transformWhereClause(pstate, j->quals, "JOIN/ON"); pstate->p_relnamespace = save_relnamespace; pstate->p_varnamespace = save_varnamespace; /* * Second, we need to check that the ON condition doesn't refer to any * rels outside the input subtrees of the JOIN. It could do that despite * our hack on the namespace if it uses fully-qualified names. So, grovel * through the transformed clause and make sure there are no bogus * references. (Outer references are OK, and are ignored here.) */ clause_varnos = pull_varnos(result); clause_varnos = bms_del_members(clause_varnos, containedRels); if ((varno = bms_first_member(clause_varnos)) >= 0) { ereport(ERROR, (errcode(ERRCODE_INVALID_COLUMN_REFERENCE), errmsg("JOIN/ON clause refers to \"%s\", which is not part of JOIN", rt_fetch(varno, pstate->p_rtable)->eref->aliasname))); } bms_free(clause_varnos); return result; } /* * transformTableEntry --- transform a RangeVar (simple relation reference) */ static RangeTblEntry * transformTableEntry(ParseState *pstate, RangeVar *r) { RangeTblEntry *rte; /* * mark this entry to indicate it comes from the FROM clause. In SQL, the * target list can only refer to range variables specified in the from * clause but we follow the more powerful POSTQUEL semantics and * automatically generate the range variable if not specified. However * there are times we need to know whether the entries are legitimate. */ rte = addRangeTableEntry(pstate, r, r->alias, interpretInhOption(r->inhOpt), true); return rte; } /* * transformRangeSubselect --- transform a sub-SELECT appearing in FROM */ static RangeTblEntry * transformRangeSubselect(ParseState *pstate, RangeSubselect *r) { Query *query; RangeTblEntry *rte; /* * We require user to supply an alias for a subselect, per SQL92. To relax * this, we'd have to be prepared to gin up a unique alias for an * unlabeled subselect. */ if (r->alias == NULL) ereport(ERROR, (errcode(ERRCODE_SYNTAX_ERROR), errmsg("subquery in FROM must have an alias"))); /* * Analyze and transform the subquery. */ query = parse_sub_analyze(r->subquery, pstate); /* * Check that we got something reasonable. Many of these conditions are * impossible given restrictions of the grammar, but check 'em anyway. */ if (query->commandType != CMD_SELECT || query->utilityStmt != NULL) elog(ERROR, "expected SELECT query from subquery in FROM"); if (query->intoClause != NULL) ereport(ERROR, (errcode(ERRCODE_SYNTAX_ERROR), errmsg("subquery in FROM cannot have SELECT INTO"))); /* * The subquery cannot make use of any variables from FROM items created * earlier in the current query. Per SQL92, the scope of a FROM item does * not include other FROM items. Formerly we hacked the namespace so that * the other variables weren't even visible, but it seems more useful to * leave them visible and give a specific error message. * * XXX this will need further work to support SQL99's LATERAL() feature, * wherein such references would indeed be legal. * * We can skip groveling through the subquery if there's not anything * visible in the current query. Also note that outer references are OK. */ if (pstate->p_relnamespace || pstate->p_varnamespace) { if (contain_vars_of_level((Node *) query, 1)) ereport(ERROR, (errcode(ERRCODE_INVALID_COLUMN_REFERENCE), errmsg("subquery in FROM cannot refer to other relations of same query level"))); } /* * OK, build an RTE for the subquery. */ rte = addRangeTableEntryForSubquery(pstate, query, r->alias, true); return rte; } /* * transformRangeFunction --- transform a function call appearing in FROM */ static RangeTblEntry * transformRangeFunction(ParseState *pstate, RangeFunction *r) { Node *funcexpr; char *funcname; RangeTblEntry *rte; /* * Get function name for possible use as alias. We use the same * transformation rules as for a SELECT output expression. For a FuncCall * node, the result will be the function name, but it is possible for the * grammar to hand back other node types. */ funcname = FigureColname(r->funccallnode); /* * Transform the raw expression. */ funcexpr = transformExpr(pstate, r->funccallnode); /* * The function parameters cannot make use of any variables from other * FROM items. (Compare to transformRangeSubselect(); the coding is * different though because we didn't parse as a sub-select with its own * level of namespace.) * * XXX this will need further work to support SQL99's LATERAL() feature, * wherein such references would indeed be legal. */ if (pstate->p_relnamespace || pstate->p_varnamespace) { if (contain_vars_of_level(funcexpr, 0)) ereport(ERROR, (errcode(ERRCODE_INVALID_COLUMN_REFERENCE), errmsg("function expression in FROM cannot refer to other relations of same query level"))); } /* * Disallow aggregate functions in the expression. (No reason to postpone * this check until parseCheckAggregates.) */ if (pstate->p_hasAggs) { if (checkExprHasAggs(funcexpr)) ereport(ERROR, (errcode(ERRCODE_GROUPING_ERROR), errmsg("cannot use aggregate function in function expression in FROM"))); } /* * OK, build an RTE for the function. */ rte = addRangeTableEntryForFunction(pstate, funcname, funcexpr, r, true); /* * If a coldeflist was supplied, ensure it defines a legal set of names * (no duplicates) and datatypes (no pseudo-types, for instance). * addRangeTableEntryForFunction looked up the type names but didn't check * them further than that. */ if (r->coldeflist) { TupleDesc tupdesc; tupdesc = BuildDescFromLists(rte->eref->colnames, rte->funccoltypes, rte->funccoltypmods); CheckAttributeNamesTypes(tupdesc, RELKIND_COMPOSITE_TYPE); } return rte; } /* * transformFromClauseItem - * Transform a FROM-clause item, adding any required entries to the * range table list being built in the ParseState, and return the * transformed item ready to include in the joinlist and namespaces. * This routine can recurse to handle SQL92 JOIN expressions. * * The function return value is the node to add to the jointree (a * RangeTblRef or JoinExpr). Additional output parameters are: * * *top_rte: receives the RTE corresponding to the jointree item. * (We could extract this from the function return node, but it saves cycles * to pass it back separately.) * * *top_rti: receives the rangetable index of top_rte. (Ditto.) * * *relnamespace: receives a List of the RTEs exposed as relation names * by this item. * * *containedRels: receives a bitmap set of the rangetable indexes * of all the base and join relations represented in this jointree item. * This is needed for checking JOIN/ON conditions in higher levels. * * We do not need to pass back an explicit varnamespace value, because * in all cases the varnamespace contribution is exactly top_rte. */ static Node * transformFromClauseItem(ParseState *pstate, Node *n, RangeTblEntry **top_rte, int *top_rti, List **relnamespace, Relids *containedRels) { if (IsA(n, RangeVar)) { /* Plain relation reference */ RangeTblRef *rtr; RangeTblEntry *rte; int rtindex; rte = transformTableEntry(pstate, (RangeVar *) n); /* assume new rte is at end */ rtindex = list_length(pstate->p_rtable); Assert(rte == rt_fetch(rtindex, pstate->p_rtable)); *top_rte = rte; *top_rti = rtindex; *relnamespace = list_make1(rte); *containedRels = bms_make_singleton(rtindex); rtr = makeNode(RangeTblRef); rtr->rtindex = rtindex; return (Node *) rtr; } else if (IsA(n, RangeSubselect)) { /* sub-SELECT is like a plain relation */ RangeTblRef *rtr; RangeTblEntry *rte; int rtindex; rte = transformRangeSubselect(pstate, (RangeSubselect *) n); /* assume new rte is at end */ rtindex = list_length(pstate->p_rtable); Assert(rte == rt_fetch(rtindex, pstate->p_rtable)); *top_rte = rte; *top_rti = rtindex; *relnamespace = list_make1(rte); *containedRels = bms_make_singleton(rtindex); rtr = makeNode(RangeTblRef); rtr->rtindex = rtindex; return (Node *) rtr; } else if (IsA(n, RangeFunction)) { /* function is like a plain relation */ RangeTblRef *rtr; RangeTblEntry *rte; int rtindex; rte = transformRangeFunction(pstate, (RangeFunction *) n); /* assume new rte is at end */ rtindex = list_length(pstate->p_rtable); Assert(rte == rt_fetch(rtindex, pstate->p_rtable)); *top_rte = rte; *top_rti = rtindex; *relnamespace = list_make1(rte); *containedRels = bms_make_singleton(rtindex); rtr = makeNode(RangeTblRef); rtr->rtindex = rtindex; return (Node *) rtr; } else if (IsA(n, JoinExpr)) { /* A newfangled join expression */ JoinExpr *j = (JoinExpr *) n; RangeTblEntry *l_rte; RangeTblEntry *r_rte; int l_rtindex; int r_rtindex; Relids l_containedRels, r_containedRels, my_containedRels; List *l_relnamespace, *r_relnamespace, *my_relnamespace, *l_colnames, *r_colnames, *res_colnames, *l_colvars, *r_colvars, *res_colvars; RangeTblEntry *rte; /* * Recursively process the left and right subtrees */ j->larg = transformFromClauseItem(pstate, j->larg, &l_rte, &l_rtindex, &l_relnamespace, &l_containedRels); j->rarg = transformFromClauseItem(pstate, j->rarg, &r_rte, &r_rtindex, &r_relnamespace, &r_containedRels); /* * Check for conflicting refnames in left and right subtrees. Must do * this because higher levels will assume I hand back a self- * consistent namespace subtree. */ checkNameSpaceConflicts(pstate, l_relnamespace, r_relnamespace); /* * Generate combined relation membership info for possible use by * transformJoinOnClause below. */ my_relnamespace = list_concat(l_relnamespace, r_relnamespace); my_containedRels = bms_join(l_containedRels, r_containedRels); pfree(r_relnamespace); /* free unneeded list header */ /* * Extract column name and var lists from both subtrees * * Note: expandRTE returns new lists, safe for me to modify */ expandRTE(l_rte, l_rtindex, 0, false, &l_colnames, &l_colvars); expandRTE(r_rte, r_rtindex, 0, false, &r_colnames, &r_colvars); /* * Natural join does not explicitly specify columns; must generate * columns to join. Need to run through the list of columns from each * table or join result and match up the column names. Use the first * table, and check every column in the second table for a match. * (We'll check that the matches were unique later on.) The result of * this step is a list of column names just like an explicitly-written * USING list. */ if (j->isNatural) { List *rlist = NIL; ListCell *lx, *rx; Assert(j->using == NIL); /* shouldn't have USING() too */ foreach(lx, l_colnames) { char *l_colname = strVal(lfirst(lx)); Value *m_name = NULL; foreach(rx, r_colnames) { char *r_colname = strVal(lfirst(rx)); if (strcmp(l_colname, r_colname) == 0) { m_name = makeString(l_colname); break; } } /* matched a right column? then keep as join column... */ if (m_name != NULL) rlist = lappend(rlist, m_name); } j->using = rlist; } /* * Now transform the join qualifications, if any. */ res_colnames = NIL; res_colvars = NIL; if (j->using) { /* * JOIN/USING (or NATURAL JOIN, as transformed above). Transform * the list into an explicit ON-condition, and generate a list of * merged result columns. */ List *ucols = j->using; List *l_usingvars = NIL; List *r_usingvars = NIL; ListCell *ucol; Assert(j->quals == NULL); /* shouldn't have ON() too */ foreach(ucol, ucols) { char *u_colname = strVal(lfirst(ucol)); ListCell *col; int ndx; int l_index = -1; int r_index = -1; Var *l_colvar, *r_colvar; /* Check for USING(foo,foo) */ foreach(col, res_colnames) { char *res_colname = strVal(lfirst(col)); if (strcmp(res_colname, u_colname) == 0) ereport(ERROR, (errcode(ERRCODE_DUPLICATE_COLUMN), errmsg("column name \"%s\" appears more than once in USING clause", u_colname))); } /* Find it in left input */ ndx = 0; foreach(col, l_colnames) { char *l_colname = strVal(lfirst(col)); if (strcmp(l_colname, u_colname) == 0) { if (l_index >= 0) ereport(ERROR, (errcode(ERRCODE_AMBIGUOUS_COLUMN), errmsg("common column name \"%s\" appears more than once in left table", u_colname))); l_index = ndx; } ndx++; } if (l_index < 0) ereport(ERROR, (errcode(ERRCODE_UNDEFINED_COLUMN), errmsg("column \"%s\" specified in USING clause does not exist in left table", u_colname))); /* Find it in right input */ ndx = 0; foreach(col, r_colnames) { char *r_colname = strVal(lfirst(col)); if (strcmp(r_colname, u_colname) == 0) { if (r_index >= 0) ereport(ERROR, (errcode(ERRCODE_AMBIGUOUS_COLUMN), errmsg("common column name \"%s\" appears more than once in right table", u_colname))); r_index = ndx; } ndx++; } if (r_index < 0) ereport(ERROR, (errcode(ERRCODE_UNDEFINED_COLUMN), errmsg("column \"%s\" specified in USING clause does not exist in right table", u_colname))); l_colvar = list_nth(l_colvars, l_index); l_usingvars = lappend(l_usingvars, l_colvar); r_colvar = list_nth(r_colvars, r_index); r_usingvars = lappend(r_usingvars, r_colvar); res_colnames = lappend(res_colnames, lfirst(ucol)); res_colvars = lappend(res_colvars, buildMergedJoinVar(pstate, j->jointype, l_colvar, r_colvar)); } j->quals = transformJoinUsingClause(pstate, l_usingvars, r_usingvars); } else if (j->quals) { /* User-written ON-condition; transform it */ j->quals = transformJoinOnClause(pstate, j, l_rte, r_rte, my_relnamespace, my_containedRels); } else { /* CROSS JOIN: no quals */ } /* Add remaining columns from each side to the output columns */ extractRemainingColumns(res_colnames, l_colnames, l_colvars, &l_colnames, &l_colvars); extractRemainingColumns(res_colnames, r_colnames, r_colvars, &r_colnames, &r_colvars); res_colnames = list_concat(res_colnames, l_colnames); res_colvars = list_concat(res_colvars, l_colvars); res_colnames = list_concat(res_colnames, r_colnames); res_colvars = list_concat(res_colvars, r_colvars); /* * Check alias (AS clause), if any. */ if (j->alias) { if (j->alias->colnames != NIL) { if (list_length(j->alias->colnames) > list_length(res_colnames)) ereport(ERROR, (errcode(ERRCODE_SYNTAX_ERROR), errmsg("column alias list for \"%s\" has too many entries", j->alias->aliasname))); } } /* * Now build an RTE for the result of the join */ rte = addRangeTableEntryForJoin(pstate, res_colnames, j->jointype, res_colvars, j->alias, true); /* assume new rte is at end */ j->rtindex = list_length(pstate->p_rtable); Assert(rte == rt_fetch(j->rtindex, pstate->p_rtable)); *top_rte = rte; *top_rti = j->rtindex; /* * Prepare returned namespace list. If the JOIN has an alias then it * hides the contained RTEs as far as the relnamespace goes; * otherwise, put the contained RTEs and *not* the JOIN into * relnamespace. */ if (j->alias) { *relnamespace = list_make1(rte); list_free(my_relnamespace); } else *relnamespace = my_relnamespace; /* * Include join RTE in returned containedRels set */ *containedRels = bms_add_member(my_containedRels, j->rtindex); return (Node *) j; } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(n)); return NULL; /* can't get here, keep compiler quiet */ } /* * buildMergedJoinVar - * generate a suitable replacement expression for a merged join column */ static Node * buildMergedJoinVar(ParseState *pstate, JoinType jointype, Var *l_colvar, Var *r_colvar) { Oid outcoltype; int32 outcoltypmod; Node *l_node, *r_node, *res_node; /* * Choose output type if input types are dissimilar. */ outcoltype = l_colvar->vartype; outcoltypmod = l_colvar->vartypmod; if (outcoltype != r_colvar->vartype) { outcoltype = select_common_type(list_make2_oid(l_colvar->vartype, r_colvar->vartype), "JOIN/USING"); outcoltypmod = -1; /* ie, unknown */ } else if (outcoltypmod != r_colvar->vartypmod) { /* same type, but not same typmod */ outcoltypmod = -1; /* ie, unknown */ } /* * Insert coercion functions if needed. Note that a difference in typmod * can only happen if input has typmod but outcoltypmod is -1. In that * case we insert a RelabelType to clearly mark that result's typmod is * not same as input. We never need coerce_type_typmod. */ if (l_colvar->vartype != outcoltype) l_node = coerce_type(pstate, (Node *) l_colvar, l_colvar->vartype, outcoltype, outcoltypmod, COERCION_IMPLICIT, COERCE_IMPLICIT_CAST); else if (l_colvar->vartypmod != outcoltypmod) l_node = (Node *) makeRelabelType((Expr *) l_colvar, outcoltype, outcoltypmod, COERCE_IMPLICIT_CAST); else l_node = (Node *) l_colvar; if (r_colvar->vartype != outcoltype) r_node = coerce_type(pstate, (Node *) r_colvar, r_colvar->vartype, outcoltype, outcoltypmod, COERCION_IMPLICIT, COERCE_IMPLICIT_CAST); else if (r_colvar->vartypmod != outcoltypmod) r_node = (Node *) makeRelabelType((Expr *) r_colvar, outcoltype, outcoltypmod, COERCE_IMPLICIT_CAST); else r_node = (Node *) r_colvar; /* * Choose what to emit */ switch (jointype) { case JOIN_INNER: /* * We can use either var; prefer non-coerced one if available. */ if (IsA(l_node, Var)) res_node = l_node; else if (IsA(r_node, Var)) res_node = r_node; else res_node = l_node; break; case JOIN_LEFT: /* Always use left var */ res_node = l_node; break; case JOIN_RIGHT: /* Always use right var */ res_node = r_node; break; case JOIN_FULL: { /* * Here we must build a COALESCE expression to ensure that the * join output is non-null if either input is. */ CoalesceExpr *c = makeNode(CoalesceExpr); c->coalescetype = outcoltype; c->args = list_make2(l_node, r_node); res_node = (Node *) c; break; } default: elog(ERROR, "unrecognized join type: %d", (int) jointype); res_node = NULL; /* keep compiler quiet */ break; } return res_node; } /* * transformWhereClause - * Transform the qualification and make sure it is of type boolean. * Used for WHERE and allied clauses. * * constructName does not affect the semantics, but is used in error messages */ Node * transformWhereClause(ParseState *pstate, Node *clause, const char *constructName) { Node *qual; if (clause == NULL) return NULL; qual = transformExpr(pstate, clause); qual = coerce_to_boolean(pstate, qual, constructName); return qual; } /* * transformLimitClause - * Transform the expression and make sure it is of type bigint. * Used for LIMIT and allied clauses. * * Note: as of Postgres 8.2, LIMIT expressions are expected to yield int8, * rather than int4 as before. * * constructName does not affect the semantics, but is used in error messages */ Node * transformLimitClause(ParseState *pstate, Node *clause, const char *constructName) { Node *qual; if (clause == NULL) return NULL; qual = transformExpr(pstate, clause); qual = coerce_to_specific_type(pstate, qual, INT8OID, constructName); /* * LIMIT can't refer to any vars or aggregates of the current query */ if (contain_vars_of_level(qual, 0)) { ereport(ERROR, (errcode(ERRCODE_INVALID_COLUMN_REFERENCE), /* translator: %s is name of a SQL construct, eg LIMIT */ errmsg("argument of %s must not contain variables", constructName))); } if (checkExprHasAggs(qual)) { ereport(ERROR, (errcode(ERRCODE_GROUPING_ERROR), /* translator: %s is name of a SQL construct, eg LIMIT */ errmsg("argument of %s must not contain aggregates", constructName))); } return qual; } /* * findTargetlistEntry - * Returns the targetlist entry matching the given (untransformed) node. * If no matching entry exists, one is created and appended to the target * list as a "resjunk" node. * * node the ORDER BY, GROUP BY, or DISTINCT ON expression to be matched * tlist the target list (passed by reference so we can append to it) * clause identifies clause type being processed */ static TargetEntry * findTargetlistEntry(ParseState *pstate, Node *node, List **tlist, int clause) { TargetEntry *target_result = NULL; ListCell *tl; Node *expr; /*---------- * Handle two special cases as mandated by the SQL92 spec: * * 1. Bare ColumnName (no qualifier or subscripts) * For a bare identifier, we search for a matching column name * in the existing target list. Multiple matches are an error * unless they refer to identical values; for example, * we allow SELECT a, a FROM table ORDER BY a * but not SELECT a AS b, b FROM table ORDER BY b * If no match is found, we fall through and treat the identifier * as an expression. * For GROUP BY, it is incorrect to match the grouping item against * targetlist entries: according to SQL92, an identifier in GROUP BY * is a reference to a column name exposed by FROM, not to a target * list column. However, many implementations (including pre-7.0 * PostgreSQL) accept this anyway. So for GROUP BY, we look first * to see if the identifier matches any FROM column name, and only * try for a targetlist name if it doesn't. This ensures that we * adhere to the spec in the case where the name could be both. * DISTINCT ON isn't in the standard, so we can do what we like there; * we choose to make it work like ORDER BY, on the rather flimsy * grounds that ordinary DISTINCT works on targetlist entries. * * 2. IntegerConstant * This means to use the n'th item in the existing target list. * Note that it would make no sense to order/group/distinct by an * actual constant, so this does not create a conflict with our * extension to order/group by an expression. * GROUP BY column-number is not allowed by SQL92, but since * the standard has no other behavior defined for this syntax, * we may as well accept this common extension. * * Note that pre-existing resjunk targets must not be used in either case, * since the user didn't write them in his SELECT list. * * If neither special case applies, fall through to treat the item as * an expression. *---------- */ if (IsA(node, ColumnRef) && list_length(((ColumnRef *) node)->fields) == 1) { char *name = strVal(linitial(((ColumnRef *) node)->fields)); int location = ((ColumnRef *) node)->location; if (clause == GROUP_CLAUSE) { /* * In GROUP BY, we must prefer a match against a FROM-clause * column to one against the targetlist. Look to see if there is * a matching column. If so, fall through to let transformExpr() * do the rest. NOTE: if name could refer ambiguously to more * than one column name exposed by FROM, colNameToVar will * ereport(ERROR). That's just what we want here. * * Small tweak for 7.4.3: ignore matches in upper query levels. * This effectively changes the search order for bare names to (1) * local FROM variables, (2) local targetlist aliases, (3) outer * FROM variables, whereas before it was (1) (3) (2). SQL92 and * SQL99 do not allow GROUPing BY an outer reference, so this * breaks no cases that are legal per spec, and it seems a more * self-consistent behavior. */ if (colNameToVar(pstate, name, true, location) != NULL) name = NULL; } if (name != NULL) { foreach(tl, *tlist) { TargetEntry *tle = (TargetEntry *) lfirst(tl); if (!tle->resjunk && strcmp(tle->resname, name) == 0) { if (target_result != NULL) { if (!equal(target_result->expr, tle->expr)) ereport(ERROR, (errcode(ERRCODE_AMBIGUOUS_COLUMN), /*------ translator: first %s is name of a SQL construct, eg ORDER BY */ errmsg("%s \"%s\" is ambiguous", clauseText[clause], name), parser_errposition(pstate, location))); } else target_result = tle; /* Stay in loop to check for ambiguity */ } } if (target_result != NULL) return target_result; /* return the first match */ } } if (IsA(node, A_Const)) { Value *val = &((A_Const *) node)->val; int targetlist_pos = 0; int target_pos; if (!IsA(val, Integer)) ereport(ERROR, (errcode(ERRCODE_SYNTAX_ERROR), /* translator: %s is name of a SQL construct, eg ORDER BY */ errmsg("non-integer constant in %s", clauseText[clause]))); target_pos = intVal(val); foreach(tl, *tlist) { TargetEntry *tle = (TargetEntry *) lfirst(tl); if (!tle->resjunk) { if (++targetlist_pos == target_pos) return tle; /* return the unique match */ } } ereport(ERROR, (errcode(ERRCODE_INVALID_COLUMN_REFERENCE), /* translator: %s is name of a SQL construct, eg ORDER BY */ errmsg("%s position %d is not in select list", clauseText[clause], target_pos))); } /* * Otherwise, we have an expression (this is a Postgres extension not * found in SQL92). Convert the untransformed node to a transformed * expression, and search for a match in the tlist. NOTE: it doesn't * really matter whether there is more than one match. Also, we are * willing to match a resjunk target here, though the above cases must * ignore resjunk targets. */ expr = transformExpr(pstate, node); foreach(tl, *tlist) { TargetEntry *tle = (TargetEntry *) lfirst(tl); if (equal(expr, tle->expr)) return tle; } /* * If no matches, construct a new target entry which is appended to the * end of the target list. This target is given resjunk = TRUE so that it * will not be projected into the final tuple. */ target_result = transformTargetEntry(pstate, node, expr, NULL, true); *tlist = lappend(*tlist, target_result); return target_result; } static GroupClause * make_group_clause(TargetEntry *tle, List *targetlist, Oid sortop, bool nulls_first) { GroupClause *result; result = makeNode(GroupClause); result->tleSortGroupRef = assignSortGroupRef(tle, targetlist); result->sortop = sortop; result->nulls_first = nulls_first; return result; } /* * transformGroupClause - * transform a GROUP BY clause * * GROUP BY items will be added to the targetlist (as resjunk columns) * if not already present, so the targetlist must be passed by reference. * * The order of the elements of the grouping clause does not affect * the semantics of the query. However, the optimizer is not currently * smart enough to reorder the grouping clause, so we try to do some * primitive reordering here. */ List * transformGroupClause(ParseState *pstate, List *grouplist, List **targetlist, List *sortClause) { List *result = NIL; List *tle_list = NIL; ListCell *l; /* Preprocess the grouping clause, lookup TLEs */ foreach(l, grouplist) { TargetEntry *tle; Oid restype; tle = findTargetlistEntry(pstate, lfirst(l), targetlist, GROUP_CLAUSE); /* if tlist item is an UNKNOWN literal, change it to TEXT */ restype = exprType((Node *) tle->expr); if (restype == UNKNOWNOID) tle->expr = (Expr *) coerce_type(pstate, (Node *) tle->expr, restype, TEXTOID, -1, COERCION_IMPLICIT, COERCE_IMPLICIT_CAST); tle_list = lappend(tle_list, tle); } /* * Now iterate through the ORDER BY clause. If we find a grouping element * that matches the ORDER BY element, append the grouping element to the * result set immediately. Otherwise, stop iterating. The effect of this * is to look for a prefix of the ORDER BY list in the grouping clauses, * and to move that prefix to the front of the GROUP BY. */ foreach(l, sortClause) { SortClause *sc = (SortClause *) lfirst(l); ListCell *prev = NULL; ListCell *tl; bool found = false; foreach(tl, tle_list) { TargetEntry *tle = (TargetEntry *) lfirst(tl); if (sc->tleSortGroupRef == tle->ressortgroupref) { GroupClause *gc; tle_list = list_delete_cell(tle_list, tl, prev); /* Use the sort clause's sorting information */ gc = make_group_clause(tle, *targetlist, sc->sortop, sc->nulls_first); result = lappend(result, gc); found = true; break; } prev = tl; } /* As soon as we've failed to match an ORDER BY element, stop */ if (!found) break; } /* * Now add any remaining elements of the GROUP BY list in the order we * received them. * * XXX: are there any additional criteria to consider when ordering * grouping clauses? */ foreach(l, tle_list) { TargetEntry *tle = (TargetEntry *) lfirst(l); GroupClause *gc; Oid sort_op; /* * Avoid making duplicate grouplist entries. Note that we don't * enforce a particular sortop here. Along with the copying of sort * information above, this means that if you write something like * "GROUP BY foo ORDER BY foo USING <<<", the GROUP BY operation * silently takes on the equality semantics implied by the ORDER BY. */ if (targetIsInSortList(tle, InvalidOid, result)) continue; sort_op = ordering_oper_opid(exprType((Node *) tle->expr)); gc = make_group_clause(tle, *targetlist, sort_op, false); result = lappend(result, gc); } list_free(tle_list); return result; } /* * transformSortClause - * transform an ORDER BY clause * * ORDER BY items will be added to the targetlist (as resjunk columns) * if not already present, so the targetlist must be passed by reference. */ List * transformSortClause(ParseState *pstate, List *orderlist, List **targetlist, bool resolveUnknown) { List *sortlist = NIL; ListCell *olitem; foreach(olitem, orderlist) { SortBy *sortby = lfirst(olitem); TargetEntry *tle; tle = findTargetlistEntry(pstate, sortby->node, targetlist, ORDER_CLAUSE); sortlist = addTargetToSortList(pstate, tle, sortlist, *targetlist, sortby->sortby_dir, sortby->sortby_nulls, sortby->useOp, resolveUnknown); } return sortlist; } /* * transformDistinctClause - * transform a DISTINCT or DISTINCT ON clause * * Since we may need to add items to the query's sortClause list, that list * is passed by reference. Likewise for the targetlist. */ List * transformDistinctClause(ParseState *pstate, List *distinctlist, List **targetlist, List **sortClause) { List *result = NIL; ListCell *slitem; ListCell *dlitem; /* No work if there was no DISTINCT clause */ if (distinctlist == NIL) return NIL; if (linitial(distinctlist) == NULL) { /* We had SELECT DISTINCT */ /* * All non-resjunk elements from target list that are not already in * the sort list should be added to it. (We don't really care what * order the DISTINCT fields are checked in, so we can leave the * user's ORDER BY spec alone, and just add additional sort keys to it * to ensure that all targetlist items get sorted.) */ *sortClause = addAllTargetsToSortList(pstate, *sortClause, *targetlist, true); /* * Now, DISTINCT list consists of all non-resjunk sortlist items. * Actually, all the sortlist items had better be non-resjunk! * Otherwise, user wrote SELECT DISTINCT with an ORDER BY item that * does not appear anywhere in the SELECT targetlist, and we can't * implement that with only one sorting pass... */ foreach(slitem, *sortClause) { SortClause *scl = (SortClause *) lfirst(slitem); TargetEntry *tle = get_sortgroupclause_tle(scl, *targetlist); if (tle->resjunk) ereport(ERROR, (errcode(ERRCODE_INVALID_COLUMN_REFERENCE), errmsg("for SELECT DISTINCT, ORDER BY expressions must appear in select list"))); else result = lappend(result, copyObject(scl)); } } else { /* We had SELECT DISTINCT ON (expr, ...) */ /* * If the user writes both DISTINCT ON and ORDER BY, then the two * expression lists must match (until one or the other runs out). * Otherwise the ORDER BY requires a different sort order than the * DISTINCT does, and we can't implement that with only one sort pass * (and if we do two passes, the results will be rather * unpredictable). However, it's OK to have more DISTINCT ON * expressions than ORDER BY expressions; we can just add the extra * DISTINCT values to the sort list, much as we did above for ordinary * DISTINCT fields. * * Actually, it'd be OK for the common prefixes of the two lists to * match in any order, but implementing that check seems like more * trouble than it's worth. */ ListCell *nextsortlist = list_head(*sortClause); foreach(dlitem, distinctlist) { TargetEntry *tle; tle = findTargetlistEntry(pstate, lfirst(dlitem), targetlist, DISTINCT_ON_CLAUSE); if (nextsortlist != NULL) { SortClause *scl = (SortClause *) lfirst(nextsortlist); if (tle->ressortgroupref != scl->tleSortGroupRef) ereport(ERROR, (errcode(ERRCODE_INVALID_COLUMN_REFERENCE), errmsg("SELECT DISTINCT ON expressions must match initial ORDER BY expressions"))); result = lappend(result, copyObject(scl)); nextsortlist = lnext(nextsortlist); } else { *sortClause = addTargetToSortList(pstate, tle, *sortClause, *targetlist, SORTBY_DEFAULT, SORTBY_NULLS_DEFAULT, NIL, true); /* * Probably, the tle should always have been added at the end * of the sort list ... but search to be safe. */ foreach(slitem, *sortClause) { SortClause *scl = (SortClause *) lfirst(slitem); if (tle->ressortgroupref == scl->tleSortGroupRef) { result = lappend(result, copyObject(scl)); break; } } if (slitem == NULL) /* should not happen */ elog(ERROR, "failed to add DISTINCT ON clause to target list"); } } } return result; } /* * addAllTargetsToSortList * Make sure all non-resjunk targets in the targetlist are in the * ORDER BY list, adding the not-yet-sorted ones to the end of the list. * This is typically used to help implement SELECT DISTINCT. * * See addTargetToSortList for info about pstate and resolveUnknown inputs. * * Returns the updated ORDER BY list. */ List * addAllTargetsToSortList(ParseState *pstate, List *sortlist, List *targetlist, bool resolveUnknown) { ListCell *l; foreach(l, targetlist) { TargetEntry *tle = (TargetEntry *) lfirst(l); if (!tle->resjunk) sortlist = addTargetToSortList(pstate, tle, sortlist, targetlist, SORTBY_DEFAULT, SORTBY_NULLS_DEFAULT, NIL, resolveUnknown); } return sortlist; } /* * addTargetToSortList * If the given targetlist entry isn't already in the ORDER BY list, * add it to the end of the list, using the given sort ordering info. * * If resolveUnknown is TRUE, convert TLEs of type UNKNOWN to TEXT. If not, * do nothing (which implies the search for a sort operator will fail). * pstate should be provided if resolveUnknown is TRUE, but can be NULL * otherwise. * * Returns the updated ORDER BY list. */ List * addTargetToSortList(ParseState *pstate, TargetEntry *tle, List *sortlist, List *targetlist, SortByDir sortby_dir, SortByNulls sortby_nulls, List *sortby_opname, bool resolveUnknown) { Oid restype = exprType((Node *) tle->expr); Oid sortop; Oid cmpfunc; bool reverse; /* if tlist item is an UNKNOWN literal, change it to TEXT */ if (restype == UNKNOWNOID && resolveUnknown) { tle->expr = (Expr *) coerce_type(pstate, (Node *) tle->expr, restype, TEXTOID, -1, COERCION_IMPLICIT, COERCE_IMPLICIT_CAST); restype = TEXTOID; } /* determine the sortop */ switch (sortby_dir) { case SORTBY_DEFAULT: case SORTBY_ASC: sortop = ordering_oper_opid(restype); reverse = false; break; case SORTBY_DESC: sortop = reverse_ordering_oper_opid(restype); reverse = true; break; case SORTBY_USING: Assert(sortby_opname != NIL); sortop = compatible_oper_opid(sortby_opname, restype, restype, false); /* * Verify it's a valid ordering operator, and determine whether to * consider it like ASC or DESC. */ if (!get_compare_function_for_ordering_op(sortop, &cmpfunc, &reverse)) ereport(ERROR, (errcode(ERRCODE_WRONG_OBJECT_TYPE), errmsg("operator %s is not a valid ordering operator", strVal(llast(sortby_opname))), errhint("Ordering operators must be \"<\" or \">\" members of btree operator families."))); break; default: elog(ERROR, "unrecognized sortby_dir: %d", sortby_dir); sortop = InvalidOid; /* keep compiler quiet */ reverse = false; break; } /* avoid making duplicate sortlist entries */ if (!targetIsInSortList(tle, sortop, sortlist)) { SortClause *sortcl = makeNode(SortClause); sortcl->tleSortGroupRef = assignSortGroupRef(tle, targetlist); sortcl->sortop = sortop; switch (sortby_nulls) { case SORTBY_NULLS_DEFAULT: /* NULLS FIRST is default for DESC; other way for ASC */ sortcl->nulls_first = reverse; break; case SORTBY_NULLS_FIRST: sortcl->nulls_first = true; break; case SORTBY_NULLS_LAST: sortcl->nulls_first = false; break; default: elog(ERROR, "unrecognized sortby_nulls: %d", sortby_nulls); break; } sortlist = lappend(sortlist, sortcl); } return sortlist; } /* * assignSortGroupRef * Assign the targetentry an unused ressortgroupref, if it doesn't * already have one. Return the assigned or pre-existing refnumber. * * 'tlist' is the targetlist containing (or to contain) the given targetentry. */ Index assignSortGroupRef(TargetEntry *tle, List *tlist) { Index maxRef; ListCell *l; if (tle->ressortgroupref) /* already has one? */ return tle->ressortgroupref; /* easiest way to pick an unused refnumber: max used + 1 */ maxRef = 0; foreach(l, tlist) { Index ref = ((TargetEntry *) lfirst(l))->ressortgroupref; if (ref > maxRef) maxRef = ref; } tle->ressortgroupref = maxRef + 1; return tle->ressortgroupref; } /* * targetIsInSortList * Is the given target item already in the sortlist? * If sortop is not InvalidOid, also test for a match to the sortop. * * It is not an oversight that this function ignores the nulls_first flag. * We check sortop when determining if an ORDER BY item is redundant with * earlier ORDER BY items, because it's conceivable that "ORDER BY * foo USING <, foo USING <<<" is not redundant, if <<< distinguishes * values that < considers equal. We need not check nulls_first * however, because a lower-order column with the same sortop but * opposite nulls direction is redundant. Also, we can consider * ORDER BY foo ASC, foo DESC redundant, so check for a commutator match. * * Works for both SortClause and GroupClause lists. Note that the main * reason we need this routine (and not just a quick test for nonzeroness * of ressortgroupref) is that a TLE might be in only one of the lists. */ bool targetIsInSortList(TargetEntry *tle, Oid sortop, List *sortList) { Index ref = tle->ressortgroupref; ListCell *l; /* no need to scan list if tle has no marker */ if (ref == 0) return false; foreach(l, sortList) { SortClause *scl = (SortClause *) lfirst(l); if (scl->tleSortGroupRef == ref && (sortop == InvalidOid || sortop == scl->sortop || sortop == get_commutator(scl->sortop))) return true; } return false; }