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Diffstat (limited to 'src/backend/parser/parse_clause.c')
| -rw-r--r-- | src/backend/parser/parse_clause.c | 1405 |
1 files changed, 0 insertions, 1405 deletions
diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c deleted file mode 100644 index 81328798eb5..00000000000 --- a/src/backend/parser/parse_clause.c +++ /dev/null @@ -1,1405 +0,0 @@ -/*------------------------------------------------------------------------- - * - * parse_clause.c - * handle clauses in parser - * - * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group - * Portions Copyright (c) 1994, Regents of the University of California - * - * - * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.94 2002/06/20 20:29:32 momjian Exp $ - * - *------------------------------------------------------------------------- - */ - -#include "postgres.h" - -#include "access/heapam.h" -#include "nodes/makefuncs.h" -#include "optimizer/clauses.h" -#include "optimizer/tlist.h" -#include "optimizer/var.h" -#include "parser/analyze.h" -#include "parser/parse.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 "parser/parse_type.h" -#include "utils/builtins.h" -#include "utils/guc.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, - List *containedRels); -static RangeTblRef *transformTableEntry(ParseState *pstate, RangeVar *r); -static RangeTblRef *transformRangeSubselect(ParseState *pstate, - RangeSubselect *r); -static RangeTblRef *transformRangeFunction(ParseState *pstate, - RangeFunction *r); -static Node *transformFromClauseItem(ParseState *pstate, Node *n, - List **containedRels); -static Node *buildMergedJoinVar(JoinType jointype, - Var *l_colvar, Var *r_colvar); -static TargetEntry *findTargetlistEntry(ParseState *pstate, Node *node, - List *tlist, int clause); -static List *addTargetToSortList(TargetEntry *tle, List *sortlist, - List *targetlist, List *opname); -static bool exprIsInSortList(Node *expr, List *sortList, List *targetList); - - -/* - * transformFromClause - - * Process the FROM clause and add items to the query's range table, - * joinlist, and namespace. - * - * Note: we assume that pstate's p_rtable, p_joinlist, and p_namespace 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) -{ - List *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 namespace. - */ - foreach(fl, frmList) - { - Node *n = lfirst(fl); - List *containedRels; - - n = transformFromClauseItem(pstate, n, &containedRels); - checkNameSpaceConflicts(pstate, (Node *) pstate->p_namespace, n); - pstate->p_joinlist = lappend(pstate->p_joinlist, n); - pstate->p_namespace = lappend(pstate->p_namespace, n); - } -} - -/* - * 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.) - * - * Returns the rangetable index of the target relation. - */ -int -setTargetTable(ParseState *pstate, RangeVar *relation, - bool inh, bool alsoSource) -{ - 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). - * - * analyze.c 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 = addRangeTableEntry(pstate, relation, NULL, inh, false); - pstate->p_target_rangetblentry = rte; - - /* assume new rte is at end */ - rtindex = length(pstate->p_rtable); - Assert(rte == rt_fetch(rtindex, pstate->p_rtable)); - - /* - * Override addRangeTableEntry's default checkForRead, and instead - * mark target table as requiring write access. - * - * If we find an explicit reference to the rel later during parse - * analysis, scanRTEForColumn will change checkForRead to 'true' - * again. That can't happen for INSERT but it is possible for UPDATE - * and DELETE. - */ - rte->checkForRead = false; - rte->checkForWrite = true; - - /* - * If UPDATE/DELETE, add table to joinlist and namespace. - */ - if (alsoSource) - addRTEtoQuery(pstate, rte, 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"); - return false; /* keep compiler quiet */ -} - -/* - * 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; - List *lnames, - *lvars = src_colvars; - - foreach(lnames, src_colnames) - { - char *colname = strVal(lfirst(lnames)); - bool match = false; - List *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)); - } - - lvars = lnext(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; - List *lvars, - *rvars = rightVars; - - /* - * 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. - */ - foreach(lvars, leftVars) - { - Node *lvar = (Node *) lfirst(lvars); - Node *rvar = (Node *) lfirst(rvars); - A_Expr *e; - - e = makeSimpleA_Expr(OP, "=", copyObject(lvar), copyObject(rvar)); - - if (result == NULL) - result = (Node *) e; - else - { - A_Expr *a; - - a = makeA_Expr(AND, NIL, result, (Node *) e); - result = (Node *) a; - } - - rvars = lnext(rvars); - } - - /* - * 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(result, "JOIN/USING"); - - return result; -} /* transformJoinUsingClause() */ - -/* transformJoinOnClause() - * Transform the qual conditions for JOIN/ON. - * Result is a transformed qualification expression. - */ -static Node * -transformJoinOnClause(ParseState *pstate, JoinExpr *j, - List *containedRels) -{ - Node *result; - List *save_namespace; - List *clause_varnos, - *l; - - /* - * 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_namespace = pstate->p_namespace; - pstate->p_namespace = makeList2(j->larg, j->rarg); - - /* This part is just like transformWhereClause() */ - result = transformExpr(pstate, j->quals); - - result = coerce_to_boolean(result, "JOIN/ON"); - - pstate->p_namespace = save_namespace; - - /* - * 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); - foreach(l, clause_varnos) - { - int varno = lfirsti(l); - - if (!intMember(varno, containedRels)) - { - elog(ERROR, "JOIN/ON clause refers to \"%s\", which is not part of JOIN", - rt_fetch(varno, pstate->p_rtable)->eref->aliasname); - } - } - freeList(clause_varnos); - - return result; -} - -/* - * transformTableEntry --- transform a RangeVar (simple relation reference) - */ -static RangeTblRef * -transformTableEntry(ParseState *pstate, RangeVar *r) -{ - RangeTblEntry *rte; - RangeTblRef *rtr; - - /* - * 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); - - /* - * We create a RangeTblRef, but we do not add it to the joinlist or - * namespace; our caller must do that if appropriate. - */ - rtr = makeNode(RangeTblRef); - /* assume new rte is at end */ - rtr->rtindex = length(pstate->p_rtable); - Assert(rte == rt_fetch(rtr->rtindex, pstate->p_rtable)); - - return rtr; -} - - -/* - * transformRangeSubselect --- transform a sub-SELECT appearing in FROM - */ -static RangeTblRef * -transformRangeSubselect(ParseState *pstate, RangeSubselect *r) -{ - List *save_namespace; - List *parsetrees; - Query *query; - RangeTblEntry *rte; - RangeTblRef *rtr; - - /* - * 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) - elog(ERROR, "sub-select in FROM must have an alias"); - - /* - * Analyze and transform the subquery. This is a bit tricky because - * we don't want the subquery to be able to see any FROM items already - * created in the current query (per SQL92, the scope of a FROM item - * does not include other FROM items). But it does need to be able to - * see any further-up parent states, so we can't just pass a null - * parent pstate link. So, temporarily make the current query level - * have an empty namespace. - */ - save_namespace = pstate->p_namespace; - pstate->p_namespace = NIL; - - parsetrees = parse_analyze(r->subquery, pstate); - - pstate->p_namespace = save_namespace; - - /* - * Check that we got something reasonable. Some of these conditions - * are probably impossible given restrictions of the grammar, but - * check 'em anyway. - */ - if (length(parsetrees) != 1) - elog(ERROR, "Unexpected parse analysis result for subselect in FROM"); - query = (Query *) lfirst(parsetrees); - if (query == NULL || !IsA(query, Query)) - elog(ERROR, "Unexpected parse analysis result for subselect in FROM"); - - if (query->commandType != CMD_SELECT) - elog(ERROR, "Expected SELECT query from subselect in FROM"); - if (query->resultRelation != 0 || query->into != NULL || query->isPortal) - elog(ERROR, "Subselect in FROM may not have SELECT INTO"); - - /* - * OK, build an RTE for the subquery. - */ - rte = addRangeTableEntryForSubquery(pstate, query, r->alias, true); - - /* - * We create a RangeTblRef, but we do not add it to the joinlist or - * namespace; our caller must do that if appropriate. - */ - rtr = makeNode(RangeTblRef); - /* assume new rte is at end */ - rtr->rtindex = length(pstate->p_rtable); - Assert(rte == rt_fetch(rtr->rtindex, pstate->p_rtable)); - - return rtr; -} - - -/* - * transformRangeFunction --- transform a function call appearing in FROM - */ -static RangeTblRef * -transformRangeFunction(ParseState *pstate, RangeFunction *r) -{ - Node *funcexpr; - char *funcname; - List *save_namespace; - RangeTblEntry *rte; - RangeTblRef *rtr; - - /* Get function name for possible use as alias */ - Assert(IsA(r->funccallnode, FuncCall)); - funcname = strVal(llast(((FuncCall *) r->funccallnode)->funcname)); - - /* - * Transform the raw FuncCall node. This is a bit tricky because we don't - * want the function expression to be able to see any FROM items already - * created in the current query (compare to transformRangeSubselect). - * But it does need to be able to see any further-up parent states. - * So, temporarily make the current query level have an empty namespace. - * NOTE: this code is OK only because the expression can't legally alter - * the namespace by causing implicit relation refs to be added. - */ - save_namespace = pstate->p_namespace; - pstate->p_namespace = NIL; - - funcexpr = transformExpr(pstate, r->funccallnode); - - pstate->p_namespace = save_namespace; - - /* - * We still need to check that the function parameters don't refer - * to any other rels. That could happen despite our hack on the namespace - * if fully-qualified names are used. So, check there are no local - * Var references in the transformed expression. (Outer references - * are OK, and are ignored here.) - */ - if (pull_varnos(funcexpr) != NIL) - elog(ERROR, "FROM function expression may not 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 (contain_agg_clause(funcexpr)) - elog(ERROR, "cannot use aggregate function in FROM function expression"); - } - - /* - * Insist we have a bare function call (explain.c is the only place - * that depends on this, I think). If this fails, it's probably because - * transformExpr interpreted the function notation as a type coercion. - */ - if (!funcexpr || - !IsA(funcexpr, Expr) || - ((Expr *) funcexpr)->opType != FUNC_EXPR) - elog(ERROR, "Coercion function not allowed in FROM clause"); - - /* - * OK, build an RTE for the function. - */ - rte = addRangeTableEntryForFunction(pstate, funcname, funcexpr, - r->alias, true); - - /* - * We create a RangeTblRef, but we do not add it to the joinlist or - * namespace; our caller must do that if appropriate. - */ - rtr = makeNode(RangeTblRef); - /* assume new rte is at end */ - rtr->rtindex = length(pstate->p_rtable); - Assert(rte == rt_fetch(rtr->rtindex, pstate->p_rtable)); - - return rtr; -} - - -/* - * 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 namespace. - * This routine can recurse to handle SQL92 JOIN expressions. - * - * Aside from the primary return value (the transformed joinlist item) - * this routine also returns an integer list of the rangetable indexes - * of all the base and join relations represented in the joinlist item. - * This list is needed for checking JOIN/ON conditions in higher levels. - */ -static Node * -transformFromClauseItem(ParseState *pstate, Node *n, List **containedRels) -{ - if (IsA(n, RangeVar)) - { - /* Plain relation reference */ - RangeTblRef *rtr; - - rtr = transformTableEntry(pstate, (RangeVar *) n); - *containedRels = makeListi1(rtr->rtindex); - return (Node *) rtr; - } - else if (IsA(n, RangeSubselect)) - { - /* sub-SELECT is like a plain relation */ - RangeTblRef *rtr; - - rtr = transformRangeSubselect(pstate, (RangeSubselect *) n); - *containedRels = makeListi1(rtr->rtindex); - return (Node *) rtr; - } - else if (IsA(n, RangeFunction)) - { - /* function is like a plain relation */ - RangeTblRef *rtr; - - rtr = transformRangeFunction(pstate, (RangeFunction *) n); - *containedRels = makeListi1(rtr->rtindex); - return (Node *) rtr; - } - else if (IsA(n, JoinExpr)) - { - /* A newfangled join expression */ - JoinExpr *j = (JoinExpr *) n; - List *my_containedRels, - *l_containedRels, - *r_containedRels, - *l_colnames, - *r_colnames, - *res_colnames, - *l_colvars, - *r_colvars, - *res_colvars; - Index leftrti, - rightrti; - RangeTblEntry *rte; - - /* - * Recursively process the left and right subtrees - */ - j->larg = transformFromClauseItem(pstate, j->larg, &l_containedRels); - j->rarg = transformFromClauseItem(pstate, j->rarg, &r_containedRels); - - /* - * Generate combined list of relation indexes for possible use - * by transformJoinOnClause below. - */ - my_containedRels = nconc(l_containedRels, 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, j->larg, j->rarg); - - /* - * Extract column name and var lists from both subtrees - * - * Note: expandRTE returns new lists, safe for me to modify - */ - if (IsA(j->larg, RangeTblRef)) - leftrti = ((RangeTblRef *) j->larg)->rtindex; - else if (IsA(j->larg, JoinExpr)) - leftrti = ((JoinExpr *) j->larg)->rtindex; - else - { - elog(ERROR, "transformFromClauseItem: unexpected subtree type"); - leftrti = 0; /* keep compiler quiet */ - } - rte = rt_fetch(leftrti, pstate->p_rtable); - expandRTE(pstate, rte, &l_colnames, &l_colvars); - - if (IsA(j->rarg, RangeTblRef)) - rightrti = ((RangeTblRef *) j->rarg)->rtindex; - else if (IsA(j->rarg, JoinExpr)) - rightrti = ((JoinExpr *) j->rarg)->rtindex; - else - { - elog(ERROR, "transformFromClauseItem: unexpected subtree type"); - rightrti = 0; /* keep compiler quiet */ - } - rte = rt_fetch(rightrti, pstate->p_rtable); - expandRTE(pstate, rte, &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; - List *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; - List *ucol; - - Assert(j->quals == NULL); /* shouldn't have ON() too */ - - foreach(ucol, ucols) - { - char *u_colname = strVal(lfirst(ucol)); - List *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) - elog(ERROR, "USING column name \"%s\" appears more than once", 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) - elog(ERROR, "Common column name \"%s\" appears more than once in left table", u_colname); - l_index = ndx; - } - ndx++; - } - if (l_index < 0) - elog(ERROR, "JOIN/USING column \"%s\" not found 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) - elog(ERROR, "Common column name \"%s\" appears more than once in right table", u_colname); - r_index = ndx; - } - ndx++; - } - if (r_index < 0) - elog(ERROR, "JOIN/USING column \"%s\" not found in right table", - u_colname); - - l_colvar = nth(l_index, l_colvars); - l_usingvars = lappend(l_usingvars, l_colvar); - r_colvar = nth(r_index, r_colvars); - r_usingvars = lappend(r_usingvars, r_colvar); - - res_colnames = lappend(res_colnames, lfirst(ucol)); - res_colvars = lappend(res_colvars, - buildMergedJoinVar(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, 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 = nconc(res_colnames, l_colnames); - res_colvars = nconc(res_colvars, l_colvars); - res_colnames = nconc(res_colnames, r_colnames); - res_colvars = nconc(res_colvars, r_colvars); - - /* - * Check alias (AS clause), if any. - */ - if (j->alias) - { - if (j->alias->colnames != NIL) - { - if (length(j->alias->colnames) > length(res_colnames)) - elog(ERROR, "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 = length(pstate->p_rtable); - Assert(rte == rt_fetch(j->rtindex, pstate->p_rtable)); - - /* - * Include join RTE in returned containedRels list - */ - *containedRels = lconsi(j->rtindex, my_containedRels); - - return (Node *) j; - } - else - elog(ERROR, "transformFromClauseItem: unexpected node (internal error)" - "\n\t%s", nodeToString(n)); - return NULL; /* can't get here, just keep compiler - * quiet */ -} - -/* - * buildMergedJoinVar - - * generate a suitable replacement expression for a merged join column - */ -static Node * -buildMergedJoinVar(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(makeListi2(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. - */ - if (l_colvar->vartype != outcoltype) - l_node = coerce_type(NULL, (Node *) l_colvar, l_colvar->vartype, - outcoltype, outcoltypmod, false); - else if (l_colvar->vartypmod != outcoltypmod) - l_node = (Node *) makeRelabelType((Node *) l_colvar, - outcoltype, outcoltypmod); - else - l_node = (Node *) l_colvar; - - if (r_colvar->vartype != outcoltype) - r_node = coerce_type(NULL, (Node *) r_colvar, r_colvar->vartype, - outcoltype, outcoltypmod, false); - else if (r_colvar->vartypmod != outcoltypmod) - r_node = (Node *) makeRelabelType((Node *) r_colvar, - outcoltype, outcoltypmod); - 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. - */ - CaseExpr *c = makeNode(CaseExpr); - CaseWhen *w = makeNode(CaseWhen); - NullTest *n = makeNode(NullTest); - - n->arg = l_node; - n->nulltesttype = IS_NOT_NULL; - w->expr = (Node *) n; - w->result = l_node; - c->casetype = outcoltype; - c->args = makeList1(w); - c->defresult = r_node; - res_node = (Node *) c; - break; - } - default: - elog(ERROR, "buildMergedJoinVar: unexpected jointype %d", - (int) jointype); - res_node = NULL; /* keep compiler quiet */ - break; - } - - return res_node; -} - - -/* - * transformWhereClause - - * transforms the qualification and make sure it is of type Boolean - */ -Node * -transformWhereClause(ParseState *pstate, Node *clause) -{ - Node *qual; - - if (clause == NULL) - return NULL; - - qual = transformExpr(pstate, clause); - - qual = coerce_to_boolean(qual, "WHERE"); - - 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 existing target list (NB: this will never be NIL, which is a - * good thing since we'd be unable to append to it if it were...) - * clause identifies clause type being processed. - */ -static TargetEntry * -findTargetlistEntry(ParseState *pstate, Node *node, List *tlist, int clause) -{ - TargetEntry *target_result = NULL; - List *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) && - length(((ColumnRef *) node)->fields) == 1 && - ((ColumnRef *) node)->indirection == NIL) - { - char *name = strVal(lfirst(((ColumnRef *) node)->fields)); - - 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 elog(ERROR). That's just what we want - * here. - */ - if (colnameToVar(pstate, name) != NULL) - name = NULL; - } - - if (name != NULL) - { - foreach(tl, tlist) - { - TargetEntry *tle = (TargetEntry *) lfirst(tl); - Resdom *resnode = tle->resdom; - - if (!resnode->resjunk && - strcmp(resnode->resname, name) == 0) - { - if (target_result != NULL) - { - if (!equal(target_result->expr, tle->expr)) - elog(ERROR, "%s '%s' is ambiguous", - clauseText[clause], name); - } - 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)) - elog(ERROR, "Non-integer constant in %s", clauseText[clause]); - target_pos = intVal(val); - foreach(tl, tlist) - { - TargetEntry *tle = (TargetEntry *) lfirst(tl); - Resdom *resnode = tle->resdom; - - if (!resnode->resjunk) - { - if (++targetlist_pos == target_pos) - return tle; /* return the unique match */ - } - } - elog(ERROR, "%s position %d is not in target 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); - lappend(tlist, target_result); - - return target_result; -} - - -/* - * transformGroupClause - - * transform a Group By clause - * - */ -List * -transformGroupClause(ParseState *pstate, List *grouplist, List *targetlist) -{ - List *glist = NIL, - *gl; - - foreach(gl, grouplist) - { - TargetEntry *tle; - - tle = findTargetlistEntry(pstate, lfirst(gl), - targetlist, GROUP_CLAUSE); - - /* avoid making duplicate grouplist entries */ - if (!exprIsInSortList(tle->expr, glist, targetlist)) - { - GroupClause *grpcl = makeNode(GroupClause); - - grpcl->tleSortGroupRef = assignSortGroupRef(tle, targetlist); - - grpcl->sortop = any_ordering_op(tle->resdom->restype); - - glist = lappend(glist, grpcl); - } - } - - return glist; -} - -/* - * transformSortClause - - * transform an ORDER BY clause - */ -List * -transformSortClause(ParseState *pstate, - List *orderlist, - List *targetlist) -{ - List *sortlist = NIL; - List *olitem; - - foreach(olitem, orderlist) - { - SortGroupBy *sortby = lfirst(olitem); - TargetEntry *tle; - - tle = findTargetlistEntry(pstate, sortby->node, - targetlist, ORDER_CLAUSE); - - sortlist = addTargetToSortList(tle, sortlist, targetlist, - sortby->useOp); - } - - 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. We might also need to add items to the query's - * targetlist, but we assume that cannot be empty initially, so we can - * lappend to it even though the pointer is passed by value. - */ -List * -transformDistinctClause(ParseState *pstate, List *distinctlist, - List *targetlist, List **sortClause) -{ - List *result = NIL; - List *slitem; - List *dlitem; - - /* No work if there was no DISTINCT clause */ - if (distinctlist == NIL) - return NIL; - - if (lfirst(distinctlist) == NIL) - { - /* 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(*sortClause, targetlist); - - /* - * 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->resdom->resjunk) - elog(ERROR, "For SELECT DISTINCT, ORDER BY expressions must appear in target 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. - */ - List *nextsortlist = *sortClause; - - foreach(dlitem, distinctlist) - { - TargetEntry *tle; - - tle = findTargetlistEntry(pstate, lfirst(dlitem), - targetlist, DISTINCT_ON_CLAUSE); - - if (nextsortlist != NIL) - { - SortClause *scl = (SortClause *) lfirst(nextsortlist); - - if (tle->resdom->ressortgroupref != scl->tleSortGroupRef) - elog(ERROR, "SELECT DISTINCT ON expressions must match initial ORDER BY expressions"); - result = lappend(result, copyObject(scl)); - nextsortlist = lnext(nextsortlist); - } - else - { - *sortClause = addTargetToSortList(tle, *sortClause, - targetlist, NIL); - - /* - * 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->resdom->ressortgroupref == scl->tleSortGroupRef) - { - result = lappend(result, copyObject(scl)); - break; - } - } - if (slitem == NIL) - elog(ERROR, "transformDistinctClause: 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. - * - * Returns the updated ORDER BY list. - */ -List * -addAllTargetsToSortList(List *sortlist, List *targetlist) -{ - List *i; - - foreach(i, targetlist) - { - TargetEntry *tle = (TargetEntry *) lfirst(i); - - if (!tle->resdom->resjunk) - sortlist = addTargetToSortList(tle, sortlist, targetlist, NIL); - } - 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 sortop with given name - * or any available sort operator if opname == NIL. - * - * Returns the updated ORDER BY list. - */ -static List * -addTargetToSortList(TargetEntry *tle, List *sortlist, List *targetlist, - List *opname) -{ - /* avoid making duplicate sortlist entries */ - if (!exprIsInSortList(tle->expr, sortlist, targetlist)) - { - SortClause *sortcl = makeNode(SortClause); - - sortcl->tleSortGroupRef = assignSortGroupRef(tle, targetlist); - - if (opname) - sortcl->sortop = compatible_oper_opid(opname, - tle->resdom->restype, - tle->resdom->restype, - false); - else - sortcl->sortop = any_ordering_op(tle->resdom->restype); - - 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; - List *l; - - if (tle->resdom->ressortgroupref) /* already has one? */ - return tle->resdom->ressortgroupref; - - /* easiest way to pick an unused refnumber: max used + 1 */ - maxRef = 0; - foreach(l, tlist) - { - Index ref = ((TargetEntry *) lfirst(l))->resdom->ressortgroupref; - - if (ref > maxRef) - maxRef = ref; - } - tle->resdom->ressortgroupref = maxRef + 1; - return tle->resdom->ressortgroupref; -} - -/* - * exprIsInSortList - * Is the given expression already in the sortlist? - * Note we will say 'yes' if it is equal() to any sortlist item, - * even though that might be a different targetlist member. - * - * Works for both SortClause and GroupClause lists. - */ -static bool -exprIsInSortList(Node *expr, List *sortList, List *targetList) -{ - List *i; - - foreach(i, sortList) - { - SortClause *scl = (SortClause *) lfirst(i); - - if (equal(expr, get_sortgroupclause_expr(scl, targetList))) - return true; - } - return false; -} |