Header And Logo
|
#include "postgres.h"#include "catalog/pg_collation.h"#include "catalog/pg_type.h"#include "nodes/nodeFuncs.h"#include "parser/analyze.h"#include "parser/parse_cte.h"#include "utils/builtins.h"#include "utils/lsyscache.h"
Go to the source code of this file.
Data Structures | |
| struct | CteItem |
| struct | CteState |
Typedefs | |
| typedef struct CteItem | CteItem |
| typedef struct CteState | CteState |
Enumerations | |
| enum | RecursionContext { RECURSION_OK, RECURSION_NONRECURSIVETERM, RECURSION_SUBLINK, RECURSION_OUTERJOIN, RECURSION_INTERSECT, RECURSION_EXCEPT } |
Functions | |
| static void | analyzeCTE (ParseState *pstate, CommonTableExpr *cte) |
| static void | makeDependencyGraph (CteState *cstate) |
| static bool | makeDependencyGraphWalker (Node *node, CteState *cstate) |
| static void | TopologicalSort (ParseState *pstate, CteItem *items, int numitems) |
| static void | checkWellFormedRecursion (CteState *cstate) |
| static bool | checkWellFormedRecursionWalker (Node *node, CteState *cstate) |
| static void | checkWellFormedSelectStmt (SelectStmt *stmt, CteState *cstate) |
| List * | transformWithClause (ParseState *pstate, WithClause *withClause) |
| void | analyzeCTETargetList (ParseState *pstate, CommonTableExpr *cte, List *tlist) |
Variables | |
| static const char *const | recursion_errormsgs [] |
| enum RecursionContext |
| RECURSION_OK | |
| RECURSION_NONRECURSIVETERM | |
| RECURSION_SUBLINK | |
| RECURSION_OUTERJOIN | |
| RECURSION_INTERSECT | |
| RECURSION_EXCEPT |
Definition at line 27 of file parse_cte.c.
{
RECURSION_OK,
RECURSION_NONRECURSIVETERM, /* inside the left-hand term */
RECURSION_SUBLINK, /* inside a sublink */
RECURSION_OUTERJOIN, /* inside nullable side of an outer join */
RECURSION_INTERSECT, /* underneath INTERSECT (ALL) */
RECURSION_EXCEPT /* underneath EXCEPT (ALL) */
} RecursionContext;
| static void analyzeCTE | ( | ParseState * | pstate, | |
| CommonTableExpr * | cte | |||
| ) | [static] |
Definition at line 237 of file parse_cte.c.
References analyzeCTETargetList(), Assert, Query::canSetTag, CMD_SELECT, Query::commandType, CommonTableExpr::ctecolcollations, CommonTableExpr::ctecoltypes, CommonTableExpr::ctecoltypmods, CommonTableExpr::ctename, CommonTableExpr::ctequery, CommonTableExpr::cterecursive, elog, ereport, errcode(), errhint(), errmsg(), ERROR, TargetEntry::expr, exprCollation(), exprLocation(), exprType(), exprTypmod(), format_type_with_typemod(), get_collation_name(), GetCTETargetList, IsA, lfirst, lfirst_int, lfirst_oid, list_head(), lnext, CommonTableExpr::location, NULL, ParseState::parentParseState, parse_sub_analyze(), parser_errposition(), TargetEntry::resjunk, TargetEntry::resno, and Query::utilityStmt.
Referenced by transformWithClause().
{
Query *query;
/* Analysis not done already */
Assert(!IsA(cte->ctequery, Query));
query = parse_sub_analyze(cte->ctequery, pstate, cte, false);
cte->ctequery = (Node *) query;
/*
* Check that we got something reasonable. These first two cases should
* be prevented by the grammar.
*/
if (!IsA(query, Query))
elog(ERROR, "unexpected non-Query statement in WITH");
if (query->utilityStmt != NULL)
elog(ERROR, "unexpected utility statement in WITH");
/*
* We disallow data-modifying WITH except at the top level of a query,
* because it's not clear when such a modification should be executed.
*/
if (query->commandType != CMD_SELECT &&
pstate->parentParseState != NULL)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("WITH clause containing a data-modifying statement must be at the top level"),
parser_errposition(pstate, cte->location)));
/*
* CTE queries are always marked not canSetTag. (Currently this only
* matters for data-modifying statements, for which the flag will be
* propagated to the ModifyTable plan node.)
*/
query->canSetTag = false;
if (!cte->cterecursive)
{
/* Compute the output column names/types if not done yet */
analyzeCTETargetList(pstate, cte, GetCTETargetList(cte));
}
else
{
/*
* Verify that the previously determined output column types and
* collations match what the query really produced. We have to check
* this because the recursive term could have overridden the
* non-recursive term, and we don't have any easy way to fix that.
*/
ListCell *lctlist,
*lctyp,
*lctypmod,
*lccoll;
int varattno;
lctyp = list_head(cte->ctecoltypes);
lctypmod = list_head(cte->ctecoltypmods);
lccoll = list_head(cte->ctecolcollations);
varattno = 0;
foreach(lctlist, GetCTETargetList(cte))
{
TargetEntry *te = (TargetEntry *) lfirst(lctlist);
Node *texpr;
if (te->resjunk)
continue;
varattno++;
Assert(varattno == te->resno);
if (lctyp == NULL || lctypmod == NULL || lccoll == NULL) /* shouldn't happen */
elog(ERROR, "wrong number of output columns in WITH");
texpr = (Node *) te->expr;
if (exprType(texpr) != lfirst_oid(lctyp) ||
exprTypmod(texpr) != lfirst_int(lctypmod))
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("recursive query \"%s\" column %d has type %s in non-recursive term but type %s overall",
cte->ctename, varattno,
format_type_with_typemod(lfirst_oid(lctyp),
lfirst_int(lctypmod)),
format_type_with_typemod(exprType(texpr),
exprTypmod(texpr))),
errhint("Cast the output of the non-recursive term to the correct type."),
parser_errposition(pstate, exprLocation(texpr))));
if (exprCollation(texpr) != lfirst_oid(lccoll))
ereport(ERROR,
(errcode(ERRCODE_COLLATION_MISMATCH),
errmsg("recursive query \"%s\" column %d has collation \"%s\" in non-recursive term but collation \"%s\" overall",
cte->ctename, varattno,
get_collation_name(lfirst_oid(lccoll)),
get_collation_name(exprCollation(texpr))),
errhint("Use the COLLATE clause to set the collation of the non-recursive term."),
parser_errposition(pstate, exprLocation(texpr))));
lctyp = lnext(lctyp);
lctypmod = lnext(lctypmod);
lccoll = lnext(lccoll);
}
if (lctyp != NULL || lctypmod != NULL || lccoll != NULL) /* shouldn't happen */
elog(ERROR, "wrong number of output columns in WITH");
}
}
| void analyzeCTETargetList | ( | ParseState * | pstate, | |
| CommonTableExpr * | cte, | |||
| List * | tlist | |||
| ) |
Definition at line 352 of file parse_cte.c.
References CommonTableExpr::aliascolnames, Assert, copyObject(), CommonTableExpr::ctecolcollations, CommonTableExpr::ctecolnames, CommonTableExpr::ctecoltypes, CommonTableExpr::ctecoltypmods, CommonTableExpr::ctename, CommonTableExpr::cterecursive, ereport, errcode(), errmsg(), ERROR, TargetEntry::expr, exprCollation(), exprType(), exprTypmod(), lappend(), lappend_int(), lappend_oid(), lfirst, list_length(), CommonTableExpr::location, makeString(), NIL, OidIsValid, parser_errposition(), pstrdup(), TargetEntry::resjunk, TargetEntry::resname, TargetEntry::resno, and UNKNOWNOID.
Referenced by analyzeCTE(), and determineRecursiveColTypes().
{
int numaliases;
int varattno;
ListCell *tlistitem;
/* Not done already ... */
Assert(cte->ctecolnames == NIL);
/*
* We need to determine column names, types, and collations. The alias
* column names override anything coming from the query itself. (Note:
* the SQL spec says that the alias list must be empty or exactly as long
* as the output column set; but we allow it to be shorter for consistency
* with Alias handling.)
*/
cte->ctecolnames = copyObject(cte->aliascolnames);
cte->ctecoltypes = cte->ctecoltypmods = cte->ctecolcollations = NIL;
numaliases = list_length(cte->aliascolnames);
varattno = 0;
foreach(tlistitem, tlist)
{
TargetEntry *te = (TargetEntry *) lfirst(tlistitem);
Oid coltype;
int32 coltypmod;
Oid colcoll;
if (te->resjunk)
continue;
varattno++;
Assert(varattno == te->resno);
if (varattno > numaliases)
{
char *attrname;
attrname = pstrdup(te->resname);
cte->ctecolnames = lappend(cte->ctecolnames, makeString(attrname));
}
coltype = exprType((Node *) te->expr);
coltypmod = exprTypmod((Node *) te->expr);
colcoll = exprCollation((Node *) te->expr);
/*
* If the CTE is recursive, force the exposed column type of any
* "unknown" column to "text". This corresponds to the fact that
* SELECT 'foo' UNION SELECT 'bar' will ultimately produce text. We
* might see "unknown" as a result of an untyped literal in the
* non-recursive term's select list, and if we don't convert to text
* then we'll have a mismatch against the UNION result.
*
* The column might contain 'foo' COLLATE "bar", so don't override
* collation if it's already set.
*/
if (cte->cterecursive && coltype == UNKNOWNOID)
{
coltype = TEXTOID;
coltypmod = -1; /* should be -1 already, but be sure */
if (!OidIsValid(colcoll))
colcoll = DEFAULT_COLLATION_OID;
}
cte->ctecoltypes = lappend_oid(cte->ctecoltypes, coltype);
cte->ctecoltypmods = lappend_int(cte->ctecoltypmods, coltypmod);
cte->ctecolcollations = lappend_oid(cte->ctecolcollations, colcoll);
}
if (varattno < numaliases)
ereport(ERROR,
(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
errmsg("WITH query \"%s\" has %d columns available but %d columns specified",
cte->ctename, varattno, numaliases),
parser_errposition(pstate, cte->location)));
}
| static void checkWellFormedRecursion | ( | CteState * | cstate | ) | [static] |
Definition at line 632 of file parse_cte.c.
References Assert, checkWellFormedRecursionWalker(), CteState::context, CteItem::cte, CommonTableExpr::ctename, CommonTableExpr::ctequery, CommonTableExpr::cterecursive, WithClause::ctes, CteState::curitem, elog, ereport, errcode(), errmsg(), ERROR, exprLocation(), i, CteState::innerwiths, IsA, CteState::items, SelectStmt::larg, SelectStmt::limitCount, SelectStmt::limitOffset, CommonTableExpr::location, SelectStmt::lockingClause, NIL, CteState::numitems, SelectStmt::op, parser_errposition(), CteState::pstate, SelectStmt::rarg, CteState::selfrefcount, SETOP_UNION, SelectStmt::sortClause, and SelectStmt::withClause.
Referenced by transformWithClause().
{
int i;
for (i = 0; i < cstate->numitems; i++)
{
CommonTableExpr *cte = cstate->items[i].cte;
SelectStmt *stmt = (SelectStmt *) cte->ctequery;
Assert(!IsA(stmt, Query)); /* not analyzed yet */
/* Ignore items that weren't found to be recursive */
if (!cte->cterecursive)
continue;
/* Must be a SELECT statement */
if (!IsA(stmt, SelectStmt))
ereport(ERROR,
(errcode(ERRCODE_INVALID_RECURSION),
errmsg("recursive query \"%s\" must not contain data-modifying statements",
cte->ctename),
parser_errposition(cstate->pstate, cte->location)));
/* Must have top-level UNION */
if (stmt->op != SETOP_UNION)
ereport(ERROR,
(errcode(ERRCODE_INVALID_RECURSION),
errmsg("recursive query \"%s\" does not have the form non-recursive-term UNION [ALL] recursive-term",
cte->ctename),
parser_errposition(cstate->pstate, cte->location)));
/* The left-hand operand mustn't contain self-reference at all */
cstate->curitem = i;
cstate->innerwiths = NIL;
cstate->selfrefcount = 0;
cstate->context = RECURSION_NONRECURSIVETERM;
checkWellFormedRecursionWalker((Node *) stmt->larg, cstate);
Assert(cstate->innerwiths == NIL);
/* Right-hand operand should contain one reference in a valid place */
cstate->curitem = i;
cstate->innerwiths = NIL;
cstate->selfrefcount = 0;
cstate->context = RECURSION_OK;
checkWellFormedRecursionWalker((Node *) stmt->rarg, cstate);
Assert(cstate->innerwiths == NIL);
if (cstate->selfrefcount != 1) /* shouldn't happen */
elog(ERROR, "missing recursive reference");
/* WITH mustn't contain self-reference, either */
if (stmt->withClause)
{
cstate->curitem = i;
cstate->innerwiths = NIL;
cstate->selfrefcount = 0;
cstate->context = RECURSION_SUBLINK;
checkWellFormedRecursionWalker((Node *) stmt->withClause->ctes,
cstate);
Assert(cstate->innerwiths == NIL);
}
/*
* Disallow ORDER BY and similar decoration atop the UNION. These
* don't make sense because it's impossible to figure out what they
* mean when we have only part of the recursive query's results. (If
* we did allow them, we'd have to check for recursive references
* inside these subtrees.)
*/
if (stmt->sortClause)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("ORDER BY in a recursive query is not implemented"),
parser_errposition(cstate->pstate,
exprLocation((Node *) stmt->sortClause))));
if (stmt->limitOffset)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("OFFSET in a recursive query is not implemented"),
parser_errposition(cstate->pstate,
exprLocation(stmt->limitOffset))));
if (stmt->limitCount)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("LIMIT in a recursive query is not implemented"),
parser_errposition(cstate->pstate,
exprLocation(stmt->limitCount))));
if (stmt->lockingClause)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("FOR UPDATE/SHARE in a recursive query is not implemented"),
parser_errposition(cstate->pstate,
exprLocation((Node *) stmt->lockingClause))));
}
}
Definition at line 731 of file parse_cte.c.
References checkWellFormedSelectStmt(), CteState::context, CteItem::cte, CommonTableExpr::ctename, CommonTableExpr::ctequery, WithClause::ctes, CteState::curitem, elog, ereport, errcode(), errmsg(), ERROR, CteState::innerwiths, IsA, CteState::items, JOIN_FULL, JOIN_INNER, JOIN_LEFT, JOIN_RIGHT, JoinExpr::jointype, lappend(), JoinExpr::larg, lcons(), lfirst, list_delete_first(), list_head(), RangeVar::location, NIL, NULL, parser_errposition(), CteState::pstate, JoinExpr::quals, JoinExpr::rarg, raw_expression_tree_walker(), recursion_errormsgs, RECURSION_OK, WithClause::recursive, RangeVar::relname, RangeVar::schemaname, CteState::selfrefcount, SubLink::subselect, SubLink::testexpr, and SelectStmt::withClause.
Referenced by checkWellFormedRecursion(), and checkWellFormedSelectStmt().
{
RecursionContext save_context = cstate->context;
if (node == NULL)
return false;
if (IsA(node, RangeVar))
{
RangeVar *rv = (RangeVar *) node;
/* If unqualified name, might be a CTE reference */
if (!rv->schemaname)
{
ListCell *lc;
CommonTableExpr *mycte;
/* ... but first see if it's captured by an inner WITH */
foreach(lc, cstate->innerwiths)
{
List *withlist = (List *) lfirst(lc);
ListCell *lc2;
foreach(lc2, withlist)
{
CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc2);
if (strcmp(rv->relname, cte->ctename) == 0)
return false; /* yes, so bail out */
}
}
/* No, could be a reference to the query level we are working on */
mycte = cstate->items[cstate->curitem].cte;
if (strcmp(rv->relname, mycte->ctename) == 0)
{
/* Found a recursive reference to the active query */
if (cstate->context != RECURSION_OK)
ereport(ERROR,
(errcode(ERRCODE_INVALID_RECURSION),
errmsg(recursion_errormsgs[cstate->context],
mycte->ctename),
parser_errposition(cstate->pstate,
rv->location)));
/* Count references */
if (++(cstate->selfrefcount) > 1)
ereport(ERROR,
(errcode(ERRCODE_INVALID_RECURSION),
errmsg("recursive reference to query \"%s\" must not appear more than once",
mycte->ctename),
parser_errposition(cstate->pstate,
rv->location)));
}
}
return false;
}
if (IsA(node, SelectStmt))
{
SelectStmt *stmt = (SelectStmt *) node;
ListCell *lc;
if (stmt->withClause)
{
if (stmt->withClause->recursive)
{
/*
* In the RECURSIVE case, all query names of the WITH are
* visible to all WITH items as well as the main query. So
* push them all on, process, pop them all off.
*/
cstate->innerwiths = lcons(stmt->withClause->ctes,
cstate->innerwiths);
foreach(lc, stmt->withClause->ctes)
{
CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
(void) checkWellFormedRecursionWalker(cte->ctequery, cstate);
}
checkWellFormedSelectStmt(stmt, cstate);
cstate->innerwiths = list_delete_first(cstate->innerwiths);
}
else
{
/*
* In the non-RECURSIVE case, query names are visible to the
* WITH items after them and to the main query.
*/
ListCell *cell1;
cstate->innerwiths = lcons(NIL, cstate->innerwiths);
cell1 = list_head(cstate->innerwiths);
foreach(lc, stmt->withClause->ctes)
{
CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
(void) checkWellFormedRecursionWalker(cte->ctequery, cstate);
lfirst(cell1) = lappend((List *) lfirst(cell1), cte);
}
checkWellFormedSelectStmt(stmt, cstate);
cstate->innerwiths = list_delete_first(cstate->innerwiths);
}
}
else
checkWellFormedSelectStmt(stmt, cstate);
/* We're done examining the SelectStmt */
return false;
}
if (IsA(node, WithClause))
{
/*
* Prevent raw_expression_tree_walker from recursing directly into a
* WITH clause. We need that to happen only under the control of the
* code above.
*/
return false;
}
if (IsA(node, JoinExpr))
{
JoinExpr *j = (JoinExpr *) node;
switch (j->jointype)
{
case JOIN_INNER:
checkWellFormedRecursionWalker(j->larg, cstate);
checkWellFormedRecursionWalker(j->rarg, cstate);
checkWellFormedRecursionWalker(j->quals, cstate);
break;
case JOIN_LEFT:
checkWellFormedRecursionWalker(j->larg, cstate);
if (save_context == RECURSION_OK)
cstate->context = RECURSION_OUTERJOIN;
checkWellFormedRecursionWalker(j->rarg, cstate);
cstate->context = save_context;
checkWellFormedRecursionWalker(j->quals, cstate);
break;
case JOIN_FULL:
if (save_context == RECURSION_OK)
cstate->context = RECURSION_OUTERJOIN;
checkWellFormedRecursionWalker(j->larg, cstate);
checkWellFormedRecursionWalker(j->rarg, cstate);
cstate->context = save_context;
checkWellFormedRecursionWalker(j->quals, cstate);
break;
case JOIN_RIGHT:
if (save_context == RECURSION_OK)
cstate->context = RECURSION_OUTERJOIN;
checkWellFormedRecursionWalker(j->larg, cstate);
cstate->context = save_context;
checkWellFormedRecursionWalker(j->rarg, cstate);
checkWellFormedRecursionWalker(j->quals, cstate);
break;
default:
elog(ERROR, "unrecognized join type: %d",
(int) j->jointype);
}
return false;
}
if (IsA(node, SubLink))
{
SubLink *sl = (SubLink *) node;
/*
* we intentionally override outer context, since subquery is
* independent
*/
cstate->context = RECURSION_SUBLINK;
checkWellFormedRecursionWalker(sl->subselect, cstate);
cstate->context = save_context;
checkWellFormedRecursionWalker(sl->testexpr, cstate);
return false;
}
return raw_expression_tree_walker(node,
checkWellFormedRecursionWalker,
(void *) cstate);
}
| static void checkWellFormedSelectStmt | ( | SelectStmt * | stmt, | |
| CteState * | cstate | |||
| ) | [static] |
Definition at line 911 of file parse_cte.c.
References checkWellFormedRecursionWalker(), CteState::context, elog, ERROR, SelectStmt::op, raw_expression_tree_walker(), RECURSION_OK, SETOP_EXCEPT, SETOP_INTERSECT, SETOP_NONE, and SETOP_UNION.
Referenced by checkWellFormedRecursionWalker().
{
RecursionContext save_context = cstate->context;
if (save_context != RECURSION_OK)
{
/* just recurse without changing state */
raw_expression_tree_walker((Node *) stmt,
checkWellFormedRecursionWalker,
(void *) cstate);
}
else
{
switch (stmt->op)
{
case SETOP_NONE:
case SETOP_UNION:
raw_expression_tree_walker((Node *) stmt,
checkWellFormedRecursionWalker,
(void *) cstate);
break;
case SETOP_INTERSECT:
if (stmt->all)
cstate->context = RECURSION_INTERSECT;
checkWellFormedRecursionWalker((Node *) stmt->larg,
cstate);
checkWellFormedRecursionWalker((Node *) stmt->rarg,
cstate);
cstate->context = save_context;
checkWellFormedRecursionWalker((Node *) stmt->sortClause,
cstate);
checkWellFormedRecursionWalker((Node *) stmt->limitOffset,
cstate);
checkWellFormedRecursionWalker((Node *) stmt->limitCount,
cstate);
checkWellFormedRecursionWalker((Node *) stmt->lockingClause,
cstate);
/* stmt->withClause is intentionally ignored here */
break;
case SETOP_EXCEPT:
if (stmt->all)
cstate->context = RECURSION_EXCEPT;
checkWellFormedRecursionWalker((Node *) stmt->larg,
cstate);
cstate->context = RECURSION_EXCEPT;
checkWellFormedRecursionWalker((Node *) stmt->rarg,
cstate);
cstate->context = save_context;
checkWellFormedRecursionWalker((Node *) stmt->sortClause,
cstate);
checkWellFormedRecursionWalker((Node *) stmt->limitOffset,
cstate);
checkWellFormedRecursionWalker((Node *) stmt->limitCount,
cstate);
checkWellFormedRecursionWalker((Node *) stmt->lockingClause,
cstate);
/* stmt->withClause is intentionally ignored here */
break;
default:
elog(ERROR, "unrecognized set op: %d",
(int) stmt->op);
}
}
}
| static void makeDependencyGraph | ( | CteState * | cstate | ) | [static] |
Definition at line 430 of file parse_cte.c.
References Assert, CteItem::cte, CommonTableExpr::ctequery, CteState::curitem, i, CteState::innerwiths, CteState::items, makeDependencyGraphWalker(), NIL, CteState::numitems, CteState::pstate, and TopologicalSort().
Referenced by transformWithClause().
{
int i;
for (i = 0; i < cstate->numitems; i++)
{
CommonTableExpr *cte = cstate->items[i].cte;
cstate->curitem = i;
cstate->innerwiths = NIL;
makeDependencyGraphWalker((Node *) cte->ctequery, cstate);
Assert(cstate->innerwiths == NIL);
}
TopologicalSort(cstate->pstate, cstate->items, cstate->numitems);
}
Definition at line 452 of file parse_cte.c.
References bms_add_member(), CteItem::cte, CommonTableExpr::ctename, CommonTableExpr::ctequery, CommonTableExpr::cterecursive, WithClause::ctes, CteState::curitem, CteItem::depends_on, i, CteItem::id, CteState::innerwiths, IsA, CteState::items, lappend(), lcons(), lfirst, list_delete_first(), list_head(), NIL, NULL, CteState::numitems, raw_expression_tree_walker(), WithClause::recursive, RangeVar::relname, RangeVar::schemaname, and SelectStmt::withClause.
Referenced by makeDependencyGraph().
{
if (node == NULL)
return false;
if (IsA(node, RangeVar))
{
RangeVar *rv = (RangeVar *) node;
/* If unqualified name, might be a CTE reference */
if (!rv->schemaname)
{
ListCell *lc;
int i;
/* ... but first see if it's captured by an inner WITH */
foreach(lc, cstate->innerwiths)
{
List *withlist = (List *) lfirst(lc);
ListCell *lc2;
foreach(lc2, withlist)
{
CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc2);
if (strcmp(rv->relname, cte->ctename) == 0)
return false; /* yes, so bail out */
}
}
/* No, could be a reference to the query level we are working on */
for (i = 0; i < cstate->numitems; i++)
{
CommonTableExpr *cte = cstate->items[i].cte;
if (strcmp(rv->relname, cte->ctename) == 0)
{
int myindex = cstate->curitem;
if (i != myindex)
{
/* Add cross-item dependency */
cstate->items[myindex].depends_on =
bms_add_member(cstate->items[myindex].depends_on,
cstate->items[i].id);
}
else
{
/* Found out this one is self-referential */
cte->cterecursive = true;
}
break;
}
}
}
return false;
}
if (IsA(node, SelectStmt))
{
SelectStmt *stmt = (SelectStmt *) node;
ListCell *lc;
if (stmt->withClause)
{
if (stmt->withClause->recursive)
{
/*
* In the RECURSIVE case, all query names of the WITH are
* visible to all WITH items as well as the main query. So
* push them all on, process, pop them all off.
*/
cstate->innerwiths = lcons(stmt->withClause->ctes,
cstate->innerwiths);
foreach(lc, stmt->withClause->ctes)
{
CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
(void) makeDependencyGraphWalker(cte->ctequery, cstate);
}
(void) raw_expression_tree_walker(node,
makeDependencyGraphWalker,
(void *) cstate);
cstate->innerwiths = list_delete_first(cstate->innerwiths);
}
else
{
/*
* In the non-RECURSIVE case, query names are visible to the
* WITH items after them and to the main query.
*/
ListCell *cell1;
cstate->innerwiths = lcons(NIL, cstate->innerwiths);
cell1 = list_head(cstate->innerwiths);
foreach(lc, stmt->withClause->ctes)
{
CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
(void) makeDependencyGraphWalker(cte->ctequery, cstate);
lfirst(cell1) = lappend((List *) lfirst(cell1), cte);
}
(void) raw_expression_tree_walker(node,
makeDependencyGraphWalker,
(void *) cstate);
cstate->innerwiths = list_delete_first(cstate->innerwiths);
}
/* We're done examining the SelectStmt */
return false;
}
/* if no WITH clause, just fall through for normal processing */
}
if (IsA(node, WithClause))
{
/*
* Prevent raw_expression_tree_walker from recursing directly into a
* WITH clause. We need that to happen only under the control of the
* code above.
*/
return false;
}
return raw_expression_tree_walker(node,
makeDependencyGraphWalker,
(void *) cstate);
}
| static void TopologicalSort | ( | ParseState * | pstate, | |
| CteItem * | items, | |||
| int | numitems | |||
| ) | [static] |
Definition at line 580 of file parse_cte.c.
References bms_del_member(), bms_is_empty(), CteItem::depends_on, ereport, errcode(), errmsg(), ERROR, i, and parser_errposition().
Referenced by makeDependencyGraph().
{
int i,
j;
/* for each position in sequence ... */
for (i = 0; i < numitems; i++)
{
/* ... scan the remaining items to find one that has no dependencies */
for (j = i; j < numitems; j++)
{
if (bms_is_empty(items[j].depends_on))
break;
}
/* if we didn't find one, the dependency graph has a cycle */
if (j >= numitems)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("mutual recursion between WITH items is not implemented"),
parser_errposition(pstate, items[i].cte->location)));
/*
* Found one. Move it to front and remove it from every other item's
* dependencies.
*/
if (i != j)
{
CteItem tmp;
tmp = items[i];
items[i] = items[j];
items[j] = tmp;
}
/*
* Items up through i are known to have no dependencies left, so we
* can skip them in this loop.
*/
for (j = i + 1; j < numitems; j++)
{
items[j].depends_on = bms_del_member(items[j].depends_on,
items[i].id);
}
}
}
| List* transformWithClause | ( | ParseState * | pstate, | |
| WithClause * | withClause | |||
| ) |
Definition at line 105 of file parse_cte.c.
References analyzeCTE(), Assert, checkWellFormedRecursion(), CteItem::cte, CommonTableExpr::ctename, CommonTableExpr::ctequery, CommonTableExpr::cterecursive, CommonTableExpr::cterefcount, WithClause::ctes, ereport, errcode(), errmsg(), ERROR, for_each_cell, i, CteItem::id, IsA, CteState::items, lappend(), lfirst, list_copy(), list_delete_first(), list_length(), lnext, CommonTableExpr::location, makeDependencyGraph(), NIL, CteState::numitems, ParseState::p_ctenamespace, ParseState::p_future_ctes, ParseState::p_hasModifyingCTE, palloc0(), parser_errposition(), CteState::pstate, and WithClause::recursive.
Referenced by transformDeleteStmt(), transformInsertStmt(), transformSelectStmt(), transformSetOperationStmt(), transformUpdateStmt(), and transformValuesClause().
{
ListCell *lc;
/* Only one WITH clause per query level */
Assert(pstate->p_ctenamespace == NIL);
Assert(pstate->p_future_ctes == NIL);
/*
* For either type of WITH, there must not be duplicate CTE names in the
* list. Check this right away so we needn't worry later.
*
* Also, tentatively mark each CTE as non-recursive, and initialize its
* reference count to zero, and set pstate->p_hasModifyingCTE if needed.
*/
foreach(lc, withClause->ctes)
{
CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
ListCell *rest;
for_each_cell(rest, lnext(lc))
{
CommonTableExpr *cte2 = (CommonTableExpr *) lfirst(rest);
if (strcmp(cte->ctename, cte2->ctename) == 0)
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_ALIAS),
errmsg("WITH query name \"%s\" specified more than once",
cte2->ctename),
parser_errposition(pstate, cte2->location)));
}
cte->cterecursive = false;
cte->cterefcount = 0;
if (!IsA(cte->ctequery, SelectStmt))
{
/* must be a data-modifying statement */
Assert(IsA(cte->ctequery, InsertStmt) ||
IsA(cte->ctequery, UpdateStmt) ||
IsA(cte->ctequery, DeleteStmt));
pstate->p_hasModifyingCTE = true;
}
}
if (withClause->recursive)
{
/*
* For WITH RECURSIVE, we rearrange the list elements if needed to
* eliminate forward references. First, build a work array and set up
* the data structure needed by the tree walkers.
*/
CteState cstate;
int i;
cstate.pstate = pstate;
cstate.numitems = list_length(withClause->ctes);
cstate.items = (CteItem *) palloc0(cstate.numitems * sizeof(CteItem));
i = 0;
foreach(lc, withClause->ctes)
{
cstate.items[i].cte = (CommonTableExpr *) lfirst(lc);
cstate.items[i].id = i;
i++;
}
/*
* Find all the dependencies and sort the CteItems into a safe
* processing order. Also, mark CTEs that contain self-references.
*/
makeDependencyGraph(&cstate);
/*
* Check that recursive queries are well-formed.
*/
checkWellFormedRecursion(&cstate);
/*
* Set up the ctenamespace for parse analysis. Per spec, all the WITH
* items are visible to all others, so stuff them all in before parse
* analysis. We build the list in safe processing order so that the
* planner can process the queries in sequence.
*/
for (i = 0; i < cstate.numitems; i++)
{
CommonTableExpr *cte = cstate.items[i].cte;
pstate->p_ctenamespace = lappend(pstate->p_ctenamespace, cte);
}
/*
* Do parse analysis in the order determined by the topological sort.
*/
for (i = 0; i < cstate.numitems; i++)
{
CommonTableExpr *cte = cstate.items[i].cte;
analyzeCTE(pstate, cte);
}
}
else
{
/*
* For non-recursive WITH, just analyze each CTE in sequence and then
* add it to the ctenamespace. This corresponds to the spec's
* definition of the scope of each WITH name. However, to allow error
* reports to be aware of the possibility of an erroneous reference,
* we maintain a list in p_future_ctes of the not-yet-visible CTEs.
*/
pstate->p_future_ctes = list_copy(withClause->ctes);
foreach(lc, withClause->ctes)
{
CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
analyzeCTE(pstate, cte);
pstate->p_ctenamespace = lappend(pstate->p_ctenamespace, cte);
pstate->p_future_ctes = list_delete_first(pstate->p_future_ctes);
}
}
return pstate->p_ctenamespace;
}
const char* const recursion_errormsgs[] [static] |
{
NULL,
gettext_noop("recursive reference to query \"%s\" must not appear within its non-recursive term"),
gettext_noop("recursive reference to query \"%s\" must not appear within a subquery"),
gettext_noop("recursive reference to query \"%s\" must not appear within an outer join"),
gettext_noop("recursive reference to query \"%s\" must not appear within INTERSECT"),
gettext_noop("recursive reference to query \"%s\" must not appear within EXCEPT")
}
Definition at line 38 of file parse_cte.c.
Referenced by checkWellFormedRecursionWalker().
1.7.1