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postgresql/src/backend/parser/parse_clause.c

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/*-------------------------------------------------------------------------
*
* parse_clause.c
* handle clauses in parser
*
* Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/parser/parse_clause.c
*
*-------------------------------------------------------------------------
*/
#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 "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/tlist.h"
#include "parser/analyze.h"
#include "parser/parsetree.h"
#include "parser/parse_clause.h"
#include "parser/parse_coerce.h"
#include "parser/parse_collate.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"
/* clause types for findTargetlistEntrySQL92 */
#define ORDER_CLAUSE 0
#define GROUP_CLAUSE 1
#define DISTINCT_ON_CLAUSE 2
static const char *const 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,
RangeTblEntry *leftRTE, RangeTblEntry *rightRTE,
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 *transformCTEReference(ParseState *pstate, RangeVar *r,
CommonTableExpr *cte, Index levelsup);
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 void checkExprIsVarFree(ParseState *pstate, Node *n,
const char *constructName);
static TargetEntry *findTargetlistEntrySQL92(ParseState *pstate, Node *node,
List **tlist, int clause);
static TargetEntry *findTargetlistEntrySQL99(ParseState *pstate, Node *node,
List **tlist);
static int get_matching_location(int sortgroupref,
List *sortgrouprefs, List *exprs);
static List *addTargetToSortList(ParseState *pstate, TargetEntry *tle,
List *sortlist, List *targetlist, SortBy *sortby,
bool resolveUnknown);
static List *addTargetToGroupList(ParseState *pstate, TargetEntry *tle,
List *grouplist, List *targetlist, int location,
bool resolveUnknown);
static WindowClause *findWindowClause(List *wclist, const char *name);
static Node *transformFrameOffset(ParseState *pstate, int frameOptions,
Node *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 = parserOpenTable(pstate, 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
* markVarForSelectPriv and its callers.
*/
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 (def->defnamespace == NULL &&
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,
RangeTblEntry *leftRTE, RangeTblEntry *rightRTE,
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.
* However, this does mean that we have to mark the columns as requiring
* SELECT privilege for ourselves; transformExpr() won't do it.
*/
forboth(lvars, leftVars, rvars, rightVars)
{
Var *lvar = (Var *) lfirst(lvars);
Var *rvar = (Var *) lfirst(rvars);
A_Expr *e;
/* Require read access to the join variables */
markVarForSelectPriv(pstate, lvar, leftRTE);
markVarForSelectPriv(pstate, rvar, rightRTE);
/* Now create the lvar = rvar join condition */
e = makeSimpleA_Expr(AEXPR_OP, "=",
copyObject(lvar), copyObject(rvar),
-1);
/* And combine into an AND clause, if multiple join columns */
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),
parser_errposition(pstate,
locate_var_of_relation(result, varno, 0))));
}
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;
}
/*
* transformCTEReference --- transform a RangeVar that references a common
* table expression (ie, a sub-SELECT defined in a WITH clause)
*/
static RangeTblEntry *
transformCTEReference(ParseState *pstate, RangeVar *r,
CommonTableExpr *cte, Index levelsup)
{
RangeTblEntry *rte;
rte = addRangeTableEntryForCTE(pstate, cte, levelsup, r, 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. (This is just elog, not ereport, because the
* grammar should have enforced it already.)
*/
if (r->alias == NULL)
elog(ERROR, "subquery in FROM must have an alias");
/*
* Analyze and transform the subquery.
*/
query = parse_sub_analyze(r->subquery, pstate, NULL,
isLockedRefname(pstate, r->alias->aliasname));
/*
* Check that we got something reasonable. Many of these conditions are
* impossible given restrictions of the grammar, but check 'em anyway.
*/
if (!IsA(query, Query) ||
query->commandType != CMD_SELECT ||
query->utilityStmt != NULL)
elog(ERROR, "unexpected non-SELECT command in subquery in FROM");
/*
* 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"),
parser_errposition(pstate,
locate_var_of_level((Node *) query, 1))));
}
/*
* 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);
/*
* We must assign collations now so that we can fill funccolcollations.
*/
assign_expr_collations(pstate, funcexpr);
/*
* 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"),
parser_errposition(pstate,
locate_var_of_level(funcexpr, 0))));
}
/*
* Disallow aggregate functions in the expression. (No reason to postpone
* this check until parseCheckAggregates.)
*/
if (pstate->p_hasAggs &&
checkExprHasAggs(funcexpr))
ereport(ERROR,
(errcode(ERRCODE_GROUPING_ERROR),
errmsg("cannot use aggregate function in function expression in FROM"),
parser_errposition(pstate,
locate_agg_of_level(funcexpr, 0))));
if (pstate->p_hasWindowFuncs &&
checkExprHasWindowFuncs(funcexpr))
ereport(ERROR,
(errcode(ERRCODE_WINDOWING_ERROR),
errmsg("cannot use window function in function expression in FROM"),
parser_errposition(pstate,
locate_windowfunc(funcexpr))));
/*
* 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,
rte->funccolcollations);
CheckAttributeNamesTypes(tupdesc, RELKIND_COMPOSITE_TYPE, false);
}
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, or perhaps a CTE reference */
RangeVar *rv = (RangeVar *) n;
RangeTblRef *rtr;
RangeTblEntry *rte = NULL;
int rtindex;
/* if it is an unqualified name, it might be a CTE reference */
if (!rv->schemaname)
{
CommonTableExpr *cte;
Index levelsup;
cte = scanNameSpaceForCTE(pstate, rv->relname, &levelsup);
if (cte)
rte = transformCTEReference(pstate, rv, cte, levelsup);
}
/* if not found as a CTE, must be a table reference */
if (!rte)
rte = transformTableEntry(pstate, rv);
/* 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;
int k;
/*
* 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, -1, false,
&l_colnames, &l_colvars);
expandRTE(r_rte, r_rtindex, 0, -1, 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->usingClause == 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->usingClause = rlist;
}
/*
* Now transform the join qualifications, if any.
*/
res_colnames = NIL;
res_colvars = NIL;
if (j->usingClause)
{
/*
* 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->usingClause;
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_rte,
r_rte,
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;
/* make a matching link to the JoinExpr for later use */
for (k = list_length(pstate->p_joinexprs) + 1; k < j->rtindex; k++)
pstate->p_joinexprs = lappend(pstate->p_joinexprs, NULL);
pstate->p_joinexprs = lappend(pstate->p_joinexprs, j);
Assert(list_length(pstate->p_joinexprs) == 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(pstate,
list_make2(l_colvar, r_colvar),
"JOIN/USING",
NULL);
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, -1);
else if (l_colvar->vartypmod != outcoltypmod)
l_node = (Node *) makeRelabelType((Expr *) l_colvar,
outcoltype, outcoltypmod,
InvalidOid, /* fixed below */
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, -1);
else if (r_colvar->vartypmod != outcoltypmod)
r_node = (Node *) makeRelabelType((Expr *) r_colvar,
outcoltype, outcoltypmod,
InvalidOid, /* fixed below */
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;
/* coalescecollid will get set below */
c->args = list_make2(l_node, r_node);
c->location = -1;
res_node = (Node *) c;
break;
}
default:
elog(ERROR, "unrecognized join type: %d", (int) jointype);
res_node = NULL; /* keep compiler quiet */
break;
}
/*
* Apply assign_expr_collations to fix up the collation info in the
* coercion and CoalesceExpr nodes, if we made any. This must be done now
* so that the join node's alias vars show correct collation info.
*/
assign_expr_collations(pstate, res_node);
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 */
checkExprIsVarFree(pstate, qual, constructName);
return qual;
}
/*
* checkExprIsVarFree
* Check that given expr has no Vars of the current query level
* (and no aggregates or window functions, either).
*
* This is used to check expressions that have to have a consistent value
* across all rows of the query, such as a LIMIT. Arguably it should reject
* volatile functions, too, but we don't do that --- whatever value the
* function gives on first execution is what you get.
*
* constructName does not affect the semantics, but is used in error messages
*/
static void
checkExprIsVarFree(ParseState *pstate, Node *n, const char *constructName)
{
if (contain_vars_of_level(n, 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),
parser_errposition(pstate,
locate_var_of_level(n, 0))));
}
if (pstate->p_hasAggs &&
checkExprHasAggs(n))
{
ereport(ERROR,
(errcode(ERRCODE_GROUPING_ERROR),
/* translator: %s is name of a SQL construct, eg LIMIT */
errmsg("argument of %s must not contain aggregate functions",
constructName),
parser_errposition(pstate,
locate_agg_of_level(n, 0))));
}
if (pstate->p_hasWindowFuncs &&
checkExprHasWindowFuncs(n))
{
ereport(ERROR,
(errcode(ERRCODE_WINDOWING_ERROR),
/* translator: %s is name of a SQL construct, eg LIMIT */
errmsg("argument of %s must not contain window functions",
constructName),
parser_errposition(pstate,
locate_windowfunc(n))));
}
}
/*
* findTargetlistEntrySQL92 -
* 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.
*
* This function supports the old SQL92 ORDER BY interpretation, where the
* expression is an output column name or number. If we fail to find a
* match of that sort, we fall through to the SQL99 rules. For historical
* reasons, Postgres also allows this interpretation for GROUP BY, though
* the standard never did. However, for GROUP BY we prefer a SQL99 match.
* This function is *not* used for WINDOW definitions.
*
* 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 *
findTargetlistEntrySQL92(ParseState *pstate, Node *node, List **tlist,
int clause)
{
ListCell *tl;
/*----------
* 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 SQL99.
* 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 per SQL99.
*----------
*/
if (IsA(node, ColumnRef) &&
list_length(((ColumnRef *) node)->fields) == 1 &&
IsA(linitial(((ColumnRef *) node)->fields), String))
{
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 use SQL99 rules.
* 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)
{
TargetEntry *target_result = 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 location = ((A_Const *) node)->location;
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]),
parser_errposition(pstate, location)));
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),
parser_errposition(pstate, location)));
}
/*
* Otherwise, we have an expression, so process it per SQL99 rules.
*/
return findTargetlistEntrySQL99(pstate, node, tlist);
}
/*
* findTargetlistEntrySQL99 -
* 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.
*
* This function supports the SQL99 interpretation, wherein the expression
* is just an ordinary expression referencing input column names.
*
* node the ORDER BY, GROUP BY, etc expression to be matched
* tlist the target list (passed by reference so we can append to it)
*/
static TargetEntry *
findTargetlistEntrySQL99(ParseState *pstate, Node *node, List **tlist)
{
TargetEntry *target_result;
ListCell *tl;
Node *expr;
/*
* 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 an existing
* resjunk target here, though the SQL92 cases above must ignore resjunk
* targets.
*/
expr = transformExpr(pstate, node);
foreach(tl, *tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(tl);
Node *texpr;
/*
* Ignore any implicit cast on the existing tlist expression.
*
* This essentially allows the ORDER/GROUP/etc item to adopt the same
* datatype previously selected for a textually-equivalent tlist item.
* There can't be any implicit cast at top level in an ordinary SELECT
* tlist at this stage, but the case does arise with ORDER BY in an
* aggregate function.
*/
texpr = strip_implicit_coercions((Node *) tle->expr);
if (equal(expr, texpr))
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;
}
/*
* 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.
*
* This is also used for window PARTITION BY clauses (which act almost the
* same, but are always interpreted per SQL99 rules).
*/
List *
transformGroupClause(ParseState *pstate, List *grouplist,
List **targetlist, List *sortClause,
bool useSQL99)
{
List *result = NIL;
ListCell *gl;
foreach(gl, grouplist)
{
Node *gexpr = (Node *) lfirst(gl);
TargetEntry *tle;
bool found = false;
if (useSQL99)
tle = findTargetlistEntrySQL99(pstate, gexpr, targetlist);
else
tle = findTargetlistEntrySQL92(pstate, gexpr, targetlist,
GROUP_CLAUSE);
/* Eliminate duplicates (GROUP BY x, x) */
if (targetIsInSortList(tle, InvalidOid, result))
continue;
/*
* If the GROUP BY tlist entry also appears in ORDER BY, copy operator
* info from the (first) matching ORDER BY item. 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. There are two reasons to do this: it improves the
* odds that we can implement both GROUP BY and ORDER BY with a single
* sort step, and it allows the user to choose the equality semantics
* used by GROUP BY, should she be working with a datatype that has
* more than one equality operator.
*/
if (tle->ressortgroupref > 0)
{
ListCell *sl;
foreach(sl, sortClause)
{
SortGroupClause *sc = (SortGroupClause *) lfirst(sl);
if (sc->tleSortGroupRef == tle->ressortgroupref)
{
result = lappend(result, copyObject(sc));
found = true;
break;
}
}
}
/*
* If no match in ORDER BY, just add it to the result using default
* sort/group semantics.
*/
if (!found)
result = addTargetToGroupList(pstate, tle,
result, *targetlist,
exprLocation(gexpr),
true);
}
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.
*
* This is also used for window and aggregate ORDER BY clauses (which act
* almost the same, but are always interpreted per SQL99 rules).
*/
List *
transformSortClause(ParseState *pstate,
List *orderlist,
List **targetlist,
bool resolveUnknown,
bool useSQL99)
{
List *sortlist = NIL;
ListCell *olitem;
foreach(olitem, orderlist)
{
SortBy *sortby = (SortBy *) lfirst(olitem);
TargetEntry *tle;
if (useSQL99)
tle = findTargetlistEntrySQL99(pstate, sortby->node, targetlist);
else
tle = findTargetlistEntrySQL92(pstate, sortby->node, targetlist,
ORDER_CLAUSE);
sortlist = addTargetToSortList(pstate, tle,
sortlist, *targetlist, sortby,
resolveUnknown);
}
return sortlist;
}
/*
* transformWindowDefinitions -
* transform window definitions (WindowDef to WindowClause)
*/
List *
transformWindowDefinitions(ParseState *pstate,
List *windowdefs,
List **targetlist)
{
List *result = NIL;
Index winref = 0;
ListCell *lc;
foreach(lc, windowdefs)
{
WindowDef *windef = (WindowDef *) lfirst(lc);
WindowClause *refwc = NULL;
List *partitionClause;
List *orderClause;
WindowClause *wc;
winref++;
/*
* Check for duplicate window names.
*/
if (windef->name &&
findWindowClause(result, windef->name) != NULL)
ereport(ERROR,
(errcode(ERRCODE_WINDOWING_ERROR),
errmsg("window \"%s\" is already defined", windef->name),
parser_errposition(pstate, windef->location)));
/*
* If it references a previous window, look that up.
*/
if (windef->refname)
{
refwc = findWindowClause(result, windef->refname);
if (refwc == NULL)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("window \"%s\" does not exist",
windef->refname),
parser_errposition(pstate, windef->location)));
}
/*
* Transform PARTITION and ORDER specs, if any. These are treated
* almost exactly like top-level GROUP BY and ORDER BY clauses,
* including the special handling of nondefault operator semantics.
*/
orderClause = transformSortClause(pstate,
windef->orderClause,
targetlist,
true /* fix unknowns */ ,
true /* force SQL99 rules */ );
partitionClause = transformGroupClause(pstate,
windef->partitionClause,
targetlist,
orderClause,
true /* force SQL99 rules */ );
/*
* And prepare the new WindowClause.
*/
wc = makeNode(WindowClause);
wc->name = windef->name;
wc->refname = windef->refname;
/*
* Per spec, a windowdef that references a previous one copies the
* previous partition clause (and mustn't specify its own). It can
* specify its own ordering clause. but only if the previous one had
* none. It always specifies its own frame clause, and the previous
* one must not have a frame clause. (Yeah, it's bizarre that each of
* these cases works differently, but SQL:2008 says so; see 7.11
* <window clause> syntax rule 10 and general rule 1.)
*/
if (refwc)
{
if (partitionClause)
ereport(ERROR,
(errcode(ERRCODE_WINDOWING_ERROR),
errmsg("cannot override PARTITION BY clause of window \"%s\"",
windef->refname),
parser_errposition(pstate, windef->location)));
wc->partitionClause = copyObject(refwc->partitionClause);
}
else
wc->partitionClause = partitionClause;
if (refwc)
{
if (orderClause && refwc->orderClause)
ereport(ERROR,
(errcode(ERRCODE_WINDOWING_ERROR),
errmsg("cannot override ORDER BY clause of window \"%s\"",
windef->refname),
parser_errposition(pstate, windef->location)));
if (orderClause)
{
wc->orderClause = orderClause;
wc->copiedOrder = false;
}
else
{
wc->orderClause = copyObject(refwc->orderClause);
wc->copiedOrder = true;
}
}
else
{
wc->orderClause = orderClause;
wc->copiedOrder = false;
}
if (refwc && refwc->frameOptions != FRAMEOPTION_DEFAULTS)
ereport(ERROR,
(errcode(ERRCODE_WINDOWING_ERROR),
errmsg("cannot override frame clause of window \"%s\"",
windef->refname),
parser_errposition(pstate, windef->location)));
wc->frameOptions = windef->frameOptions;
/* Process frame offset expressions */
wc->startOffset = transformFrameOffset(pstate, wc->frameOptions,
windef->startOffset);
wc->endOffset = transformFrameOffset(pstate, wc->frameOptions,
windef->endOffset);
wc->winref = winref;
result = lappend(result, wc);
}
return result;
}
/*
* transformDistinctClause -
* transform a DISTINCT clause
*
* Since we may need to add items to the query's targetlist, that list
* is passed by reference.
*
* As with GROUP BY, we absorb the sorting semantics of ORDER BY as much as
* possible into the distinctClause. This avoids a possible need to re-sort,
* and allows the user to choose the equality semantics used by DISTINCT,
* should she be working with a datatype that has more than one equality
* operator.
*
* is_agg is true if we are transforming an aggregate(DISTINCT ...)
* function call. This does not affect any behavior, only the phrasing
* of error messages.
*/
List *
transformDistinctClause(ParseState *pstate,
List **targetlist, List *sortClause, bool is_agg)
{
List *result = NIL;
ListCell *slitem;
ListCell *tlitem;
/*
* The distinctClause should consist of all ORDER BY items followed by all
* other non-resjunk targetlist items. There must not be any resjunk
* ORDER BY items --- that would imply that we are sorting by a value that
* isn't necessarily unique within a DISTINCT group, so the results
* wouldn't be well-defined. This construction ensures we follow the rule
* that sortClause and distinctClause match; in fact the sortClause will
* always be a prefix of distinctClause.
*
* Note a corner case: the same TLE could be in the ORDER BY list multiple
* times with different sortops. We have to include it in the
* distinctClause the same way to preserve the prefix property. The net
* effect will be that the TLE value will be made unique according to both
* sortops.
*/
foreach(slitem, sortClause)
{
SortGroupClause *scl = (SortGroupClause *) lfirst(slitem);
TargetEntry *tle = get_sortgroupclause_tle(scl, *targetlist);
if (tle->resjunk)
ereport(ERROR,
(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
is_agg ?
errmsg("in an aggregate with DISTINCT, ORDER BY expressions must appear in argument list") :
errmsg("for SELECT DISTINCT, ORDER BY expressions must appear in select list"),
parser_errposition(pstate,
exprLocation((Node *) tle->expr))));
result = lappend(result, copyObject(scl));
}
/*
* Now add any remaining non-resjunk tlist items, using default sort/group
* semantics for their data types.
*/
foreach(tlitem, *targetlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(tlitem);
if (tle->resjunk)
continue; /* ignore junk */
result = addTargetToGroupList(pstate, tle,
result, *targetlist,
exprLocation((Node *) tle->expr),
true);
}
return result;
}
/*
* transformDistinctOnClause -
* transform a DISTINCT ON clause
*
* Since we may need to add items to the query's targetlist, that list
* is passed by reference.
*
* As with GROUP BY, we absorb the sorting semantics of ORDER BY as much as
* possible into the distinctClause. This avoids a possible need to re-sort,
* and allows the user to choose the equality semantics used by DISTINCT,
* should she be working with a datatype that has more than one equality
* operator.
*/
List *
transformDistinctOnClause(ParseState *pstate, List *distinctlist,
List **targetlist, List *sortClause)
{
List *result = NIL;
List *sortgrouprefs = NIL;
bool skipped_sortitem;
ListCell *lc;
ListCell *lc2;
/*
* Add all the DISTINCT ON expressions to the tlist (if not already
* present, they are added as resjunk items). Assign sortgroupref numbers
* to them, and make a list of these numbers. (NB: we rely below on the
* sortgrouprefs list being one-for-one with the original distinctlist.
* Also notice that we could have duplicate DISTINCT ON expressions and
* hence duplicate entries in sortgrouprefs.)
*/
foreach(lc, distinctlist)
{
Node *dexpr = (Node *) lfirst(lc);
int sortgroupref;
TargetEntry *tle;
tle = findTargetlistEntrySQL92(pstate, dexpr, targetlist,
DISTINCT_ON_CLAUSE);
sortgroupref = assignSortGroupRef(tle, *targetlist);
sortgrouprefs = lappend_int(sortgrouprefs, sortgroupref);
}
/*
* If the user writes both DISTINCT ON and ORDER BY, adopt the sorting
* semantics from ORDER BY items that match DISTINCT ON items, and also
* adopt their column sort order. We insist that the distinctClause and
* sortClause match, so throw error if we find the need to add any more
* distinctClause items after we've skipped an ORDER BY item that wasn't
* in DISTINCT ON.
*/
skipped_sortitem = false;
foreach(lc, sortClause)
{
SortGroupClause *scl = (SortGroupClause *) lfirst(lc);
if (list_member_int(sortgrouprefs, scl->tleSortGroupRef))
{
if (skipped_sortitem)
ereport(ERROR,
(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
errmsg("SELECT DISTINCT ON expressions must match initial ORDER BY expressions"),
parser_errposition(pstate,
get_matching_location(scl->tleSortGroupRef,
sortgrouprefs,
distinctlist))));
else
result = lappend(result, copyObject(scl));
}
else
skipped_sortitem = true;
}
/*
* Now add any remaining DISTINCT ON items, using default sort/group
* semantics for their data types. (Note: this is pretty questionable; if
* the ORDER BY list doesn't include all the DISTINCT ON items and more
* besides, you certainly aren't using DISTINCT ON in the intended way,
* and you probably aren't going to get consistent results. It might be
* better to throw an error or warning here. But historically we've
* allowed it, so keep doing so.)
*/
forboth(lc, distinctlist, lc2, sortgrouprefs)
{
Node *dexpr = (Node *) lfirst(lc);
int sortgroupref = lfirst_int(lc2);
TargetEntry *tle = get_sortgroupref_tle(sortgroupref, *targetlist);
if (targetIsInSortList(tle, InvalidOid, result))
continue; /* already in list (with some semantics) */
if (skipped_sortitem)
ereport(ERROR,
(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
errmsg("SELECT DISTINCT ON expressions must match initial ORDER BY expressions"),
parser_errposition(pstate, exprLocation(dexpr))));
result = addTargetToGroupList(pstate, tle,
result, *targetlist,
exprLocation(dexpr),
true);
}
return result;
}
/*
* get_matching_location
* Get the exprLocation of the exprs member corresponding to the
* (first) member of sortgrouprefs that equals sortgroupref.
*
* This is used so that we can point at a troublesome DISTINCT ON entry.
* (Note that we need to use the original untransformed DISTINCT ON list
* item, as whatever TLE it corresponds to will very possibly have a
* parse location pointing to some matching entry in the SELECT list
* or ORDER BY list.)
*/
static int
get_matching_location(int sortgroupref, List *sortgrouprefs, List *exprs)
{
ListCell *lcs;
ListCell *lce;
forboth(lcs, sortgrouprefs, lce, exprs)
{
if (lfirst_int(lcs) == sortgroupref)
return exprLocation((Node *) lfirst(lce));
}
/* if no match, caller blew it */
elog(ERROR, "get_matching_location: no matching sortgroupref");
return -1; /* keep compiler quiet */
}
/*
* addTargetToSortList
* If the given targetlist entry isn't already in the SortGroupClause
* 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 SortGroupClause list.
*/
static List *
addTargetToSortList(ParseState *pstate, TargetEntry *tle,
List *sortlist, List *targetlist, SortBy *sortby,
bool resolveUnknown)
{
Oid restype = exprType((Node *) tle->expr);
Oid sortop;
Oid eqop;
bool hashable;
bool reverse;
int location;
ParseCallbackState pcbstate;
/* 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,
-1);
restype = TEXTOID;
}
/*
* Rather than clutter the API of get_sort_group_operators and the other
* functions we're about to use, make use of error context callback to
* mark any error reports with a parse position. We point to the operator
* location if present, else to the expression being sorted. (NB: use the
* original untransformed expression here; the TLE entry might well point
* at a duplicate expression in the regular SELECT list.)
*/
location = sortby->location;
if (location < 0)
location = exprLocation(sortby->node);
setup_parser_errposition_callback(&pcbstate, pstate, location);
/* determine the sortop, eqop, and directionality */
switch (sortby->sortby_dir)
{
case SORTBY_DEFAULT:
case SORTBY_ASC:
get_sort_group_operators(restype,
true, true, false,
&sortop, &eqop, NULL,
&hashable);
reverse = false;
break;
case SORTBY_DESC:
get_sort_group_operators(restype,
false, true, true,
NULL, &eqop, &sortop,
&hashable);
reverse = true;
break;
case SORTBY_USING:
Assert(sortby->useOp != NIL);
sortop = compatible_oper_opid(sortby->useOp,
restype,
restype,
false);
/*
* Verify it's a valid ordering operator, fetch the corresponding
* equality operator, and determine whether to consider it like
* ASC or DESC.
*/
eqop = get_equality_op_for_ordering_op(sortop, &reverse);
if (!OidIsValid(eqop))
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("operator %s is not a valid ordering operator",
strVal(llast(sortby->useOp))),
errhint("Ordering operators must be \"<\" or \">\" members of btree operator families.")));
/*
* Also see if the equality operator is hashable.
*/
hashable = op_hashjoinable(eqop, restype);
break;
default:
elog(ERROR, "unrecognized sortby_dir: %d", sortby->sortby_dir);
sortop = InvalidOid; /* keep compiler quiet */
eqop = InvalidOid;
hashable = false;
reverse = false;
break;
}
cancel_parser_errposition_callback(&pcbstate);
/* avoid making duplicate sortlist entries */
if (!targetIsInSortList(tle, sortop, sortlist))
{
SortGroupClause *sortcl = makeNode(SortGroupClause);
sortcl->tleSortGroupRef = assignSortGroupRef(tle, targetlist);
sortcl->eqop = eqop;
sortcl->sortop = sortop;
sortcl->hashable = hashable;
switch (sortby->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->sortby_nulls);
break;
}
sortlist = lappend(sortlist, sortcl);
}
return sortlist;
}
/*
* addTargetToGroupList
* If the given targetlist entry isn't already in the SortGroupClause
* list, add it to the end of the list, using default sort/group
* semantics.
*
* This is very similar to addTargetToSortList, except that we allow the
* case where only a grouping (equality) operator can be found, and that
* the TLE is considered "already in the list" if it appears there with any
* sorting semantics.
*
* location is the parse location to be fingered in event of trouble. Note
* that we can't rely on exprLocation(tle->expr), because that might point
* to a SELECT item that matches the GROUP BY item; it'd be pretty confusing
* to report such a location.
*
* If resolveUnknown is TRUE, convert TLEs of type UNKNOWN to TEXT. If not,
* do nothing (which implies the search for an equality operator will fail).
* pstate should be provided if resolveUnknown is TRUE, but can be NULL
* otherwise.
*
* Returns the updated SortGroupClause list.
*/
static List *
addTargetToGroupList(ParseState *pstate, TargetEntry *tle,
List *grouplist, List *targetlist, int location,
bool resolveUnknown)
{
Oid restype = exprType((Node *) tle->expr);
/* 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,
-1);
restype = TEXTOID;
}
/* avoid making duplicate grouplist entries */
if (!targetIsInSortList(tle, InvalidOid, grouplist))
{
SortGroupClause *grpcl = makeNode(SortGroupClause);
Oid sortop;
Oid eqop;
bool hashable;
ParseCallbackState pcbstate;
setup_parser_errposition_callback(&pcbstate, pstate, location);
/* determine the eqop and optional sortop */
get_sort_group_operators(restype,
false, true, false,
&sortop, &eqop, NULL,
&hashable);
cancel_parser_errposition_callback(&pcbstate);
grpcl->tleSortGroupRef = assignSortGroupRef(tle, targetlist);
grpcl->eqop = eqop;
grpcl->sortop = sortop;
grpcl->nulls_first = false; /* OK with or without sortop */
grpcl->hashable = hashable;
grouplist = lappend(grouplist, grpcl);
}
return grouplist;
}
/*
* 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 ordering and grouping lists (sortop would normally be
* InvalidOid when considering grouping). 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)
{
SortGroupClause *scl = (SortGroupClause *) lfirst(l);
if (scl->tleSortGroupRef == ref &&
(sortop == InvalidOid ||
sortop == scl->sortop ||
sortop == get_commutator(scl->sortop)))
return true;
}
return false;
}
/*
* findWindowClause
* Find the named WindowClause in the list, or return NULL if not there
*/
static WindowClause *
findWindowClause(List *wclist, const char *name)
{
ListCell *l;
foreach(l, wclist)
{
WindowClause *wc = (WindowClause *) lfirst(l);
if (wc->name && strcmp(wc->name, name) == 0)
return wc;
}
return NULL;
}
/*
* transformFrameOffset
* Process a window frame offset expression
*/
static Node *
transformFrameOffset(ParseState *pstate, int frameOptions, Node *clause)
{
const char *constructName = NULL;
Node *node;
/* Quick exit if no offset expression */
if (clause == NULL)
return NULL;
/* Transform the raw expression tree */
node = transformExpr(pstate, clause);
if (frameOptions & FRAMEOPTION_ROWS)
{
/*
* Like LIMIT clause, simply coerce to int8
*/
constructName = "ROWS";
node = coerce_to_specific_type(pstate, node, INT8OID, constructName);
}
else if (frameOptions & FRAMEOPTION_RANGE)
{
/*
* this needs a lot of thought to decide how to support in the context
* of Postgres' extensible datatype framework
*/
constructName = "RANGE";
/* error was already thrown by gram.y, this is just a backstop */
elog(ERROR, "window frame with value offset is not implemented");
}
else
Assert(false);
/* Disallow variables and aggregates in frame offsets */
checkExprIsVarFree(pstate, node, constructName);
return node;
}
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