database/postgres
database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-04-25 21:42:33 +03:00
Code
postgres/src/backend/parser/parse_target.c
Magnus Hagander 9f2e211386 Remove cvs keywords from all files.
2010-09-20 22:08:53 +02:00

1595 lines
44 KiB
C
Raw Blame History

/*-------------------------------------------------------------------------
*
* parse_target.c
* handle target lists
*
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/parser/parse_target.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "catalog/pg_type.h"
#include "commands/dbcommands.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "parser/parsetree.h"
#include "parser/parse_coerce.h"
#include "parser/parse_expr.h"
#include "parser/parse_func.h"
#include "parser/parse_relation.h"
#include "parser/parse_target.h"
#include "parser/parse_type.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/typcache.h"
static void markTargetListOrigin(ParseState *pstate, TargetEntry *tle,
Var *var, int levelsup);
static Node *transformAssignmentIndirection(ParseState *pstate,
Node *basenode,
const char *targetName,
bool targetIsArray,
Oid targetTypeId,
int32 targetTypMod,
ListCell *indirection,
Node *rhs,
int location);
static List *ExpandColumnRefStar(ParseState *pstate, ColumnRef *cref,
bool targetlist);
static List *ExpandAllTables(ParseState *pstate, int location);
static List *ExpandIndirectionStar(ParseState *pstate, A_Indirection *ind,
bool targetlist);
static List *ExpandSingleTable(ParseState *pstate, RangeTblEntry *rte,
int location, bool targetlist);
static List *ExpandRowReference(ParseState *pstate, Node *expr,
bool targetlist);
static int FigureColnameInternal(Node *node, char **name);
/*
* transformTargetEntry()
* Transform any ordinary "expression-type" node into a targetlist entry.
* This is exported so that parse_clause.c can generate targetlist entries
* for ORDER/GROUP BY items that are not already in the targetlist.
*
* node the (untransformed) parse tree for the value expression.
* expr the transformed expression, or NULL if caller didn't do it yet.
* colname the column name to be assigned, or NULL if none yet set.
* resjunk true if the target should be marked resjunk, ie, it is not
* wanted in the final projected tuple.
*/
TargetEntry *
transformTargetEntry(ParseState *pstate,
Node *node,
Node *expr,
char *colname,
bool resjunk)
{
/* Transform the node if caller didn't do it already */
if (expr == NULL)
expr = transformExpr(pstate, node);
if (colname == NULL && !resjunk)
{
/*
* Generate a suitable column name for a column without any explicit
* 'AS ColumnName' clause.
*/
colname = FigureColname(node);
}
return makeTargetEntry((Expr *) expr,
(AttrNumber) pstate->p_next_resno++,
colname,
resjunk);
}
/*
* transformTargetList()
* Turns a list of ResTarget's into a list of TargetEntry's.
*
* At this point, we don't care whether we are doing SELECT, INSERT,
* or UPDATE; we just transform the given expressions (the "val" fields).
*/
List *
transformTargetList(ParseState *pstate, List *targetlist)
{
List *p_target = NIL;
ListCell *o_target;
foreach(o_target, targetlist)
{
ResTarget *res = (ResTarget *) lfirst(o_target);
/*
* Check for "something.*". Depending on the complexity of the
* "something", the star could appear as the last field in ColumnRef,
* or as the last indirection item in A_Indirection.
*/
if (IsA(res->val, ColumnRef))
{
ColumnRef *cref = (ColumnRef *) res->val;
if (IsA(llast(cref->fields), A_Star))
{
/* It is something.*, expand into multiple items */
p_target = list_concat(p_target,
ExpandColumnRefStar(pstate, cref,
true));
continue;
}
}
else if (IsA(res->val, A_Indirection))
{
A_Indirection *ind = (A_Indirection *) res->val;
if (IsA(llast(ind->indirection), A_Star))
{
/* It is something.*, expand into multiple items */
p_target = list_concat(p_target,
ExpandIndirectionStar(pstate, ind,
true));
continue;
}
}
/*
* Not "something.*", so transform as a single expression
*/
p_target = lappend(p_target,
transformTargetEntry(pstate,
res->val,
NULL,
res->name,
false));
}
return p_target;
}
/*
* transformExpressionList()
*
* This is the identical transformation to transformTargetList, except that
* the input list elements are bare expressions without ResTarget decoration,
* and the output elements are likewise just expressions without TargetEntry
* decoration. We use this for ROW() and VALUES() constructs.
*/
List *
transformExpressionList(ParseState *pstate, List *exprlist)
{
List *result = NIL;
ListCell *lc;
foreach(lc, exprlist)
{
Node *e = (Node *) lfirst(lc);
/*
* Check for "something.*". Depending on the complexity of the
* "something", the star could appear as the last field in ColumnRef,
* or as the last indirection item in A_Indirection.
*/
if (IsA(e, ColumnRef))
{
ColumnRef *cref = (ColumnRef *) e;
if (IsA(llast(cref->fields), A_Star))
{
/* It is something.*, expand into multiple items */
result = list_concat(result,
ExpandColumnRefStar(pstate, cref,
false));
continue;
}
}
else if (IsA(e, A_Indirection))
{
A_Indirection *ind = (A_Indirection *) e;
if (IsA(llast(ind->indirection), A_Star))
{
/* It is something.*, expand into multiple items */
result = list_concat(result,
ExpandIndirectionStar(pstate, ind,
false));
continue;
}
}
/*
* Not "something.*", so transform as a single expression
*/
result = lappend(result,
transformExpr(pstate, e));
}
return result;
}
/*
* markTargetListOrigins()
* Mark targetlist columns that are simple Vars with the source
* table's OID and column number.
*
* Currently, this is done only for SELECT targetlists, since we only
* need the info if we are going to send it to the frontend.
*/
void
markTargetListOrigins(ParseState *pstate, List *targetlist)
{
ListCell *l;
foreach(l, targetlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(l);
markTargetListOrigin(pstate, tle, (Var *) tle->expr, 0);
}
}
/*
* markTargetListOrigin()
* If 'var' is a Var of a plain relation, mark 'tle' with its origin
*
* levelsup is an extra offset to interpret the Var's varlevelsup correctly.
*
* This is split out so it can recurse for join references. Note that we
* do not drill down into views, but report the view as the column owner.
*/
static void
markTargetListOrigin(ParseState *pstate, TargetEntry *tle,
Var *var, int levelsup)
{
int netlevelsup;
RangeTblEntry *rte;
AttrNumber attnum;
if (var == NULL || !IsA(var, Var))
return;
netlevelsup = var->varlevelsup + levelsup;
rte = GetRTEByRangeTablePosn(pstate, var->varno, netlevelsup);
attnum = var->varattno;
switch (rte->rtekind)
{
case RTE_RELATION:
/* It's a table or view, report it */
tle->resorigtbl = rte->relid;
tle->resorigcol = attnum;
break;
case RTE_SUBQUERY:
/* Subselect-in-FROM: copy up from the subselect */
if (attnum != InvalidAttrNumber)
{
TargetEntry *ste = get_tle_by_resno(rte->subquery->targetList,
attnum);
if (ste == NULL || ste->resjunk)
elog(ERROR, "subquery %s does not have attribute %d",
rte->eref->aliasname, attnum);
tle->resorigtbl = ste->resorigtbl;
tle->resorigcol = ste->resorigcol;
}
break;
case RTE_JOIN:
/* Join RTE --- recursively inspect the alias variable */
if (attnum != InvalidAttrNumber)
{
Var *aliasvar;
Assert(attnum > 0 && attnum <= list_length(rte->joinaliasvars));
aliasvar = (Var *) list_nth(rte->joinaliasvars, attnum - 1);
markTargetListOrigin(pstate, tle, aliasvar, netlevelsup);
}
break;
case RTE_SPECIAL:
case RTE_FUNCTION:
case RTE_VALUES:
/* not a simple relation, leave it unmarked */
break;
case RTE_CTE:
/*
* CTE reference: copy up from the subquery, if possible. If the
* RTE is a recursive self-reference then we can't do anything
* because we haven't finished analyzing it yet. However, it's no
* big loss because we must be down inside the recursive term of a
* recursive CTE, and so any markings on the current targetlist
* are not going to affect the results anyway.
*/
if (attnum != InvalidAttrNumber && !rte->self_reference)
{
CommonTableExpr *cte = GetCTEForRTE(pstate, rte, netlevelsup);
TargetEntry *ste;
/* should be analyzed by now */
Assert(IsA(cte->ctequery, Query));
ste = get_tle_by_resno(((Query *) cte->ctequery)->targetList,
attnum);
if (ste == NULL || ste->resjunk)
elog(ERROR, "subquery %s does not have attribute %d",
rte->eref->aliasname, attnum);
tle->resorigtbl = ste->resorigtbl;
tle->resorigcol = ste->resorigcol;
}
break;
}
}
/*
* transformAssignedExpr()
* This is used in INSERT and UPDATE statements only. It prepares an
* expression for assignment to a column of the target table.
* This includes coercing the given value to the target column's type
* (if necessary), and dealing with any subfield names or subscripts
* attached to the target column itself. The input expression has
* already been through transformExpr().
*
* pstate parse state
* expr expression to be modified
* colname target column name (ie, name of attribute to be assigned to)
* attrno target attribute number
* indirection subscripts/field names for target column, if any
* location error cursor position for the target column, or -1
*
* Returns the modified expression.
*
* Note: location points at the target column name (SET target or INSERT
* column name list entry), and must therefore be -1 in an INSERT that
* omits the column name list. So we should usually prefer to use
* exprLocation(expr) for errors that can happen in a default INSERT.
*/
Expr *
transformAssignedExpr(ParseState *pstate,
Expr *expr,
char *colname,
int attrno,
List *indirection,
int location)
{
Oid type_id; /* type of value provided */
Oid attrtype; /* type of target column */
int32 attrtypmod;
Relation rd = pstate->p_target_relation;
Assert(rd != NULL);
if (attrno <= 0)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot assign to system column \"%s\"",
colname),
parser_errposition(pstate, location)));
attrtype = attnumTypeId(rd, attrno);
attrtypmod = rd->rd_att->attrs[attrno - 1]->atttypmod;
/*
* If the expression is a DEFAULT placeholder, insert the attribute's
* type/typmod into it so that exprType will report the right things. (We
* expect that the eventually substituted default expression will in fact
* have this type and typmod.) Also, reject trying to update a subfield
* or array element with DEFAULT, since there can't be any default for
* portions of a column.
*/
if (expr && IsA(expr, SetToDefault))
{
SetToDefault *def = (SetToDefault *) expr;
def->typeId = attrtype;
def->typeMod = attrtypmod;
if (indirection)
{
if (IsA(linitial(indirection), A_Indices))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot set an array element to DEFAULT"),
parser_errposition(pstate, location)));
else
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot set a subfield to DEFAULT"),
parser_errposition(pstate, location)));
}
}
/* Now we can use exprType() safely. */
type_id = exprType((Node *) expr);
/*
* If there is indirection on the target column, prepare an array or
* subfield assignment expression. This will generate a new column value
* that the source value has been inserted into, which can then be placed
* in the new tuple constructed by INSERT or UPDATE.
*/
if (indirection)
{
Node *colVar;
if (pstate->p_is_insert)
{
/*
* The command is INSERT INTO table (col.something) ... so there
* is not really a source value to work with. Insert a NULL
* constant as the source value.
*/
colVar = (Node *) makeNullConst(attrtype, attrtypmod);
}
else
{
/*
* Build a Var for the column to be updated.
*/
colVar = (Node *) make_var(pstate,
pstate->p_target_rangetblentry,
attrno,
location);
}
expr = (Expr *)
transformAssignmentIndirection(pstate,
colVar,
colname,
false,
attrtype,
attrtypmod,
list_head(indirection),
(Node *) expr,
location);
}
else
{
/*
* For normal non-qualified target column, do type checking and
* coercion.
*/
Node *orig_expr = (Node *) expr;
expr = (Expr *)
coerce_to_target_type(pstate,
orig_expr, type_id,
attrtype, attrtypmod,
COERCION_ASSIGNMENT,
COERCE_IMPLICIT_CAST,
-1);
if (expr == NULL)
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("column \"%s\" is of type %s"
" but expression is of type %s",
colname,
format_type_be(attrtype),
format_type_be(type_id)),
errhint("You will need to rewrite or cast the expression."),
parser_errposition(pstate, exprLocation(orig_expr))));
}
return expr;
}
/*
* updateTargetListEntry()
* This is used in UPDATE statements only. It prepares an UPDATE
* TargetEntry for assignment to a column of the target table.
* This includes coercing the given value to the target column's type
* (if necessary), and dealing with any subfield names or subscripts
* attached to the target column itself.
*
* pstate parse state
* tle target list entry to be modified
* colname target column name (ie, name of attribute to be assigned to)
* attrno target attribute number
* indirection subscripts/field names for target column, if any
* location error cursor position (should point at column name), or -1
*/
void
updateTargetListEntry(ParseState *pstate,
TargetEntry *tle,
char *colname,
int attrno,
List *indirection,
int location)
{
/* Fix up expression as needed */
tle->expr = transformAssignedExpr(pstate,
tle->expr,
colname,
attrno,
indirection,
location);
/*
* Set the resno to identify the target column --- the rewriter and
* planner depend on this. We also set the resname to identify the target
* column, but this is only for debugging purposes; it should not be
* relied on. (In particular, it might be out of date in a stored rule.)
*/
tle->resno = (AttrNumber) attrno;
tle->resname = colname;
}
/*
* Process indirection (field selection or subscripting) of the target
* column in INSERT/UPDATE. This routine recurses for multiple levels
* of indirection --- but note that several adjacent A_Indices nodes in
* the indirection list are treated as a single multidimensional subscript
* operation.
*
* In the initial call, basenode is a Var for the target column in UPDATE,
* or a null Const of the target's type in INSERT. In recursive calls,
* basenode is NULL, indicating that a substitute node should be consed up if
* needed.
*
* targetName is the name of the field or subfield we're assigning to, and
* targetIsArray is true if we're subscripting it. These are just for
* error reporting.
*
* targetTypeId and targetTypMod indicate the datatype of the object to
* be assigned to (initially the target column, later some subobject).
*
* indirection is the sublist remaining to process. When it's NULL, we're
* done recursing and can just coerce and return the RHS.
*
* rhs is the already-transformed value to be assigned; note it has not been
* coerced to any particular type.
*
* location is the cursor error position for any errors. (Note: this points
* to the head of the target clause, eg "foo" in "foo.bar[baz]". Later we
* might want to decorate indirection cells with their own location info,
* in which case the location argument could probably be dropped.)
*/
static Node *
transformAssignmentIndirection(ParseState *pstate,
Node *basenode,
const char *targetName,
bool targetIsArray,
Oid targetTypeId,
int32 targetTypMod,
ListCell *indirection,
Node *rhs,
int location)
{
Node *result;
List *subscripts = NIL;
bool isSlice = false;
ListCell *i;
if (indirection && !basenode)
{
/* Set up a substitution. We reuse CaseTestExpr for this. */
CaseTestExpr *ctest = makeNode(CaseTestExpr);
ctest->typeId = targetTypeId;
ctest->typeMod = targetTypMod;
basenode = (Node *) ctest;
}
/*
* We have to split any field-selection operations apart from
* subscripting. Adjacent A_Indices nodes have to be treated as a single
* multidimensional subscript operation.
*/
for_each_cell(i, indirection)
{
Node *n = lfirst(i);
if (IsA(n, A_Indices))
{
subscripts = lappend(subscripts, n);
if (((A_Indices *) n)->lidx != NULL)
isSlice = true;
}
else if (IsA(n, A_Star))
{
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("row expansion via \"*\" is not supported here"),
parser_errposition(pstate, location)));
}
else
{
FieldStore *fstore;
Oid typrelid;
AttrNumber attnum;
Oid fieldTypeId;
int32 fieldTypMod;
Assert(IsA(n, String));
/* process subscripts before this field selection */
if (subscripts)
{
Oid elementTypeId = transformArrayType(targetTypeId);
Oid typeNeeded = isSlice ? targetTypeId : elementTypeId;
/* recurse to create appropriate RHS for array assign */
rhs = transformAssignmentIndirection(pstate,
NULL,
targetName,
true,
typeNeeded,
targetTypMod,
i,
rhs,
location);
/* process subscripts */
return (Node *) transformArraySubscripts(pstate,
basenode,
targetTypeId,
elementTypeId,
targetTypMod,
subscripts,
rhs);
}
/* No subscripts, so can process field selection here */
typrelid = typeidTypeRelid(targetTypeId);
if (!typrelid)
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("cannot assign to field \"%s\" of column \"%s\" because its type %s is not a composite type",
strVal(n), targetName,
format_type_be(targetTypeId)),
parser_errposition(pstate, location)));
attnum = get_attnum(typrelid, strVal(n));
if (attnum == InvalidAttrNumber)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_COLUMN),
errmsg("cannot assign to field \"%s\" of column \"%s\" because there is no such column in data type %s",
strVal(n), targetName,
format_type_be(targetTypeId)),
parser_errposition(pstate, location)));
if (attnum < 0)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_COLUMN),
errmsg("cannot assign to system column \"%s\"",
strVal(n)),
parser_errposition(pstate, location)));
get_atttypetypmod(typrelid, attnum,
&fieldTypeId, &fieldTypMod);
/* recurse to create appropriate RHS for field assign */
rhs = transformAssignmentIndirection(pstate,
NULL,
strVal(n),
false,
fieldTypeId,
fieldTypMod,
lnext(i),
rhs,
location);
/* and build a FieldStore node */
fstore = makeNode(FieldStore);
fstore->arg = (Expr *) basenode;
fstore->newvals = list_make1(rhs);
fstore->fieldnums = list_make1_int(attnum);
fstore->resulttype = targetTypeId;
return (Node *) fstore;
}
}
/* process trailing subscripts, if any */
if (subscripts)
{
Oid elementTypeId = transformArrayType(targetTypeId);
Oid typeNeeded = isSlice ? targetTypeId : elementTypeId;
/* recurse to create appropriate RHS for array assign */
rhs = transformAssignmentIndirection(pstate,
NULL,
targetName,
true,
typeNeeded,
targetTypMod,
NULL,
rhs,
location);
/* process subscripts */
return (Node *) transformArraySubscripts(pstate,
basenode,
targetTypeId,
elementTypeId,
targetTypMod,
subscripts,
rhs);
}
/* base case: just coerce RHS to match target type ID */
result = coerce_to_target_type(pstate,
rhs, exprType(rhs),
targetTypeId, targetTypMod,
COERCION_ASSIGNMENT,
COERCE_IMPLICIT_CAST,
-1);
if (result == NULL)
{
if (targetIsArray)
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("array assignment to \"%s\" requires type %s"
" but expression is of type %s",
targetName,
format_type_be(targetTypeId),
format_type_be(exprType(rhs))),
errhint("You will need to rewrite or cast the expression."),
parser_errposition(pstate, location)));
else
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("subfield \"%s\" is of type %s"
" but expression is of type %s",
targetName,
format_type_be(targetTypeId),
format_type_be(exprType(rhs))),
errhint("You will need to rewrite or cast the expression."),
parser_errposition(pstate, location)));
}
return result;
}
/*
* checkInsertTargets -
* generate a list of INSERT column targets if not supplied, or
* test supplied column names to make sure they are in target table.
* Also return an integer list of the columns' attribute numbers.
*/
List *
checkInsertTargets(ParseState *pstate, List *cols, List **attrnos)
{
*attrnos = NIL;
if (cols == NIL)
{
/*
* Generate default column list for INSERT.
*/
Form_pg_attribute *attr = pstate->p_target_relation->rd_att->attrs;
int numcol = pstate->p_target_relation->rd_rel->relnatts;
int i;
for (i = 0; i < numcol; i++)
{
ResTarget *col;
if (attr[i]->attisdropped)
continue;
col = makeNode(ResTarget);
col->name = pstrdup(NameStr(attr[i]->attname));
col->indirection = NIL;
col->val = NULL;
col->location = -1;
cols = lappend(cols, col);
*attrnos = lappend_int(*attrnos, i + 1);
}
}
else
{
/*
* Do initial validation of user-supplied INSERT column list.
*/
Bitmapset *wholecols = NULL;
Bitmapset *partialcols = NULL;
ListCell *tl;
foreach(tl, cols)
{
ResTarget *col = (ResTarget *) lfirst(tl);
char *name = col->name;
int attrno;
/* Lookup column name, ereport on failure */
attrno = attnameAttNum(pstate->p_target_relation, name, false);
if (attrno == InvalidAttrNumber)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_COLUMN),
errmsg("column \"%s\" of relation \"%s\" does not exist",
name,
RelationGetRelationName(pstate->p_target_relation)),
parser_errposition(pstate, col->location)));
/*
* Check for duplicates, but only of whole columns --- we allow
* INSERT INTO foo (col.subcol1, col.subcol2)
*/
if (col->indirection == NIL)
{
/* whole column; must not have any other assignment */
if (bms_is_member(attrno, wholecols) ||
bms_is_member(attrno, partialcols))
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_COLUMN),
errmsg("column \"%s\" specified more than once",
name),
parser_errposition(pstate, col->location)));
wholecols = bms_add_member(wholecols, attrno);
}
else
{
/* partial column; must not have any whole assignment */
if (bms_is_member(attrno, wholecols))
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_COLUMN),
errmsg("column \"%s\" specified more than once",
name),
parser_errposition(pstate, col->location)));
partialcols = bms_add_member(partialcols, attrno);
}
*attrnos = lappend_int(*attrnos, attrno);
}
}
return cols;
}
/*
* ExpandColumnRefStar()
* Transforms foo.* into a list of expressions or targetlist entries.
*
* This handles the case where '*' appears as the last or only item in a
* ColumnRef. The code is shared between the case of foo.* at the top level
* in a SELECT target list (where we want TargetEntry nodes in the result)
* and foo.* in a ROW() or VALUES() construct (where we want just bare
* expressions).
*
* The referenced columns are marked as requiring SELECT access.
*/
static List *
ExpandColumnRefStar(ParseState *pstate, ColumnRef *cref,
bool targetlist)
{
List *fields = cref->fields;
int numnames = list_length(fields);
if (numnames == 1)
{
/*
* Target item is a bare '*', expand all tables
*
* (e.g., SELECT * FROM emp, dept)
*
* Since the grammar only accepts bare '*' at top level of SELECT, we
* need not handle the targetlist==false case here.
*/
Assert(targetlist);
return ExpandAllTables(pstate, cref->location);
}
else
{
/*
* Target item is relation.*, expand that table
*
* (e.g., SELECT emp.*, dname FROM emp, dept)
*
* Note: this code is a lot like transformColumnRef; it's tempting to
* call that instead and then replace the resulting whole-row Var with
* a list of Vars. However, that would leave us with the RTE's
* selectedCols bitmap showing the whole row as needing select
* permission, as well as the individual columns. That would be
* incorrect (since columns added later shouldn't need select
* permissions). We could try to remove the whole-row permission bit
* after the fact, but duplicating code is less messy.
*/
char *nspname = NULL;
char *relname = NULL;
RangeTblEntry *rte = NULL;
int levels_up;
enum
{
CRSERR_NO_RTE,
CRSERR_WRONG_DB,
CRSERR_TOO_MANY
} crserr = CRSERR_NO_RTE;
/*
* Give the PreParseColumnRefHook, if any, first shot. If it returns
* non-null then we should use that expression.
*/
if (pstate->p_pre_columnref_hook != NULL)
{
Node *node;
node = (*pstate->p_pre_columnref_hook) (pstate, cref);
if (node != NULL)
return ExpandRowReference(pstate, node, targetlist);
}
switch (numnames)
{
case 2:
relname = strVal(linitial(fields));
rte = refnameRangeTblEntry(pstate, nspname, relname,
cref->location,
&levels_up);
break;
case 3:
nspname = strVal(linitial(fields));
relname = strVal(lsecond(fields));
rte = refnameRangeTblEntry(pstate, nspname, relname,
cref->location,
&levels_up);
break;
case 4:
{
char *catname = strVal(linitial(fields));
/*
* We check the catalog name and then ignore it.
*/
if (strcmp(catname, get_database_name(MyDatabaseId)) != 0)
{
crserr = CRSERR_WRONG_DB;
break;
}
nspname = strVal(lsecond(fields));
relname = strVal(lthird(fields));
rte = refnameRangeTblEntry(pstate, nspname, relname,
cref->location,
&levels_up);
break;
}
default:
crserr = CRSERR_TOO_MANY;
break;
}
/*
* Now give the PostParseColumnRefHook, if any, a chance. We cheat a
* bit by passing the RangeTblEntry, not a Var, as the planned
* translation. (A single Var wouldn't be strictly correct anyway.
* This convention allows hooks that really care to know what is
* happening.)
*/
if (pstate->p_post_columnref_hook != NULL)
{
Node *node;
node = (*pstate->p_post_columnref_hook) (pstate, cref,
(Node *) rte);
if (node != NULL)
{
if (rte != NULL)
ereport(ERROR,
(errcode(ERRCODE_AMBIGUOUS_COLUMN),
errmsg("column reference \"%s\" is ambiguous",
NameListToString(cref->fields)),
parser_errposition(pstate, cref->location)));
return ExpandRowReference(pstate, node, targetlist);
}
}
/*
* Throw error if no translation found.
*/
if (rte == NULL)
{
switch (crserr)
{
case CRSERR_NO_RTE:
errorMissingRTE(pstate, makeRangeVar(nspname, relname,
cref->location));
break;
case CRSERR_WRONG_DB:
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cross-database references are not implemented: %s",
NameListToString(cref->fields)),
parser_errposition(pstate, cref->location)));
break;
case CRSERR_TOO_MANY:
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("improper qualified name (too many dotted names): %s",
NameListToString(cref->fields)),
parser_errposition(pstate, cref->location)));
break;
}
}
/*
* OK, expand the RTE into fields.
*/
return ExpandSingleTable(pstate, rte, cref->location, targetlist);
}
}
/*
* ExpandAllTables()
* Transforms '*' (in the target list) into a list of targetlist entries.
*
* tlist entries are generated for each relation appearing in the query's
* varnamespace. We do not consider relnamespace because that would include
* input tables of aliasless JOINs, NEW/OLD pseudo-entries, etc.
*
* The referenced relations/columns are marked as requiring SELECT access.
*/
static List *
ExpandAllTables(ParseState *pstate, int location)
{
List *target = NIL;
ListCell *l;
/* Check for SELECT *; */
if (!pstate->p_varnamespace)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("SELECT * with no tables specified is not valid"),
parser_errposition(pstate, location)));
foreach(l, pstate->p_varnamespace)
{
RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
int rtindex = RTERangeTablePosn(pstate, rte, NULL);
target = list_concat(target,
expandRelAttrs(pstate, rte, rtindex, 0,
location));
}
return target;
}
/*
* ExpandIndirectionStar()
* Transforms foo.* into a list of expressions or targetlist entries.
*
* This handles the case where '*' appears as the last item in A_Indirection.
* The code is shared between the case of foo.* at the top level in a SELECT
* target list (where we want TargetEntry nodes in the result) and foo.* in
* a ROW() or VALUES() construct (where we want just bare expressions).
*/
static List *
ExpandIndirectionStar(ParseState *pstate, A_Indirection *ind,
bool targetlist)
{
Node *expr;
/* Strip off the '*' to create a reference to the rowtype object */
ind = copyObject(ind);
ind->indirection = list_truncate(ind->indirection,
list_length(ind->indirection) - 1);
/* And transform that */
expr = transformExpr(pstate, (Node *) ind);
/* Expand the rowtype expression into individual fields */
return ExpandRowReference(pstate, expr, targetlist);
}
/*
* ExpandSingleTable()
* Transforms foo.* into a list of expressions or targetlist entries.
*
* This handles the case where foo has been determined to be a simple
* reference to an RTE, so we can just generate Vars for the expressions.
*
* The referenced columns are marked as requiring SELECT access.
*/
static List *
ExpandSingleTable(ParseState *pstate, RangeTblEntry *rte,
int location, bool targetlist)
{
int sublevels_up;
int rtindex;
rtindex = RTERangeTablePosn(pstate, rte, &sublevels_up);
if (targetlist)
{
/* expandRelAttrs handles permissions marking */
return expandRelAttrs(pstate, rte, rtindex, sublevels_up,
location);
}
else
{
List *vars;
ListCell *l;
expandRTE(rte, rtindex, sublevels_up, location, false,
NULL, &vars);
/*
* Require read access to the table. This is normally redundant with
* the markVarForSelectPriv calls below, but not if the table has zero
* columns.
*/
rte->requiredPerms |= ACL_SELECT;
/* Require read access to each column */
foreach(l, vars)
{
Var *var = (Var *) lfirst(l);
markVarForSelectPriv(pstate, var, rte);
}
return vars;
}
}
/*
* ExpandRowReference()
* Transforms foo.* into a list of expressions or targetlist entries.
*
* This handles the case where foo is an arbitrary expression of composite
* type.
*/
static List *
ExpandRowReference(ParseState *pstate, Node *expr,
bool targetlist)
{
List *result = NIL;
TupleDesc tupleDesc;
int numAttrs;
int i;
/*
* If the rowtype expression is a whole-row Var, we can expand the fields
* as simple Vars. Note: if the RTE is a relation, this case leaves us
* with the RTE's selectedCols bitmap showing the whole row as needing
* select permission, as well as the individual columns. However, we can
* only get here for weird notations like (table.*).*, so it's not worth
* trying to clean up --- arguably, the permissions marking is correct
* anyway for such cases.
*/
if (IsA(expr, Var) &&
((Var *) expr)->varattno == InvalidAttrNumber)
{
Var *var = (Var *) expr;
RangeTblEntry *rte;
rte = GetRTEByRangeTablePosn(pstate, var->varno, var->varlevelsup);
return ExpandSingleTable(pstate, rte, var->location, targetlist);
}
/*
* Otherwise we have to do it the hard way. Our current implementation is
* to generate multiple copies of the expression and do FieldSelects.
* (This can be pretty inefficient if the expression involves nontrivial
* computation :-(.)
*
* Verify it's a composite type, and get the tupdesc. We use
* get_expr_result_type() because that can handle references to functions
* returning anonymous record types. If that fails, use
* lookup_rowtype_tupdesc(), which will almost certainly fail as well, but
* it will give an appropriate error message.
*
* If it's a Var of type RECORD, we have to work even harder: we have to
* find what the Var refers to, and pass that to get_expr_result_type.
* That task is handled by expandRecordVariable().
*/
if (IsA(expr, Var) &&
((Var *) expr)->vartype == RECORDOID)
tupleDesc = expandRecordVariable(pstate, (Var *) expr, 0);
else if (get_expr_result_type(expr, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
tupleDesc = lookup_rowtype_tupdesc_copy(exprType(expr),
exprTypmod(expr));
Assert(tupleDesc);
/* Generate a list of references to the individual fields */
numAttrs = tupleDesc->natts;
for (i = 0; i < numAttrs; i++)
{
Form_pg_attribute att = tupleDesc->attrs[i];
FieldSelect *fselect;
if (att->attisdropped)
continue;
fselect = makeNode(FieldSelect);
fselect->arg = (Expr *) copyObject(expr);
fselect->fieldnum = i + 1;
fselect->resulttype = att->atttypid;
fselect->resulttypmod = att->atttypmod;
if (targetlist)
{
/* add TargetEntry decoration */
TargetEntry *te;
te = makeTargetEntry((Expr *) fselect,
(AttrNumber) pstate->p_next_resno++,
pstrdup(NameStr(att->attname)),
false);
result = lappend(result, te);
}
else
result = lappend(result, fselect);
}
return result;
}
/*
* expandRecordVariable
* Get the tuple descriptor for a Var of type RECORD, if possible.
*
* Since no actual table or view column is allowed to have type RECORD, such
* a Var must refer to a JOIN or FUNCTION RTE or to a subquery output. We
* drill down to find the ultimate defining expression and attempt to infer
* the tupdesc from it. We ereport if we can't determine the tupdesc.
*
* levelsup is an extra offset to interpret the Var's varlevelsup correctly.
*/
TupleDesc
expandRecordVariable(ParseState *pstate, Var *var, int levelsup)
{
TupleDesc tupleDesc;
int netlevelsup;
RangeTblEntry *rte;
AttrNumber attnum;
Node *expr;
/* Check my caller didn't mess up */
Assert(IsA(var, Var));
Assert(var->vartype == RECORDOID);
netlevelsup = var->varlevelsup + levelsup;
rte = GetRTEByRangeTablePosn(pstate, var->varno, netlevelsup);
attnum = var->varattno;
if (attnum == InvalidAttrNumber)
{
/* Whole-row reference to an RTE, so expand the known fields */
List *names,
*vars;
ListCell *lname,
*lvar;
int i;
expandRTE(rte, var->varno, 0, var->location, false,
&names, &vars);
tupleDesc = CreateTemplateTupleDesc(list_length(vars), false);
i = 1;
forboth(lname, names, lvar, vars)
{
char *label = strVal(lfirst(lname));
Node *varnode = (Node *) lfirst(lvar);
TupleDescInitEntry(tupleDesc, i,
label,
exprType(varnode),
exprTypmod(varnode),
0);
i++;
}
Assert(lname == NULL && lvar == NULL); /* lists same length? */
return tupleDesc;
}
expr = (Node *) var; /* default if we can't drill down */
switch (rte->rtekind)
{
case RTE_RELATION:
case RTE_SPECIAL:
case RTE_VALUES:
/*
* This case should not occur: a column of a table or values list
* shouldn't have type RECORD. Fall through and fail (most
* likely) at the bottom.
*/
break;
case RTE_SUBQUERY:
{
/* Subselect-in-FROM: examine sub-select's output expr */
TargetEntry *ste = get_tle_by_resno(rte->subquery->targetList,
attnum);
if (ste == NULL || ste->resjunk)
elog(ERROR, "subquery %s does not have attribute %d",
rte->eref->aliasname, attnum);
expr = (Node *) ste->expr;
if (IsA(expr, Var))
{
/*
* Recurse into the sub-select to see what its Var refers
* to. We have to build an additional level of ParseState
* to keep in step with varlevelsup in the subselect.
*/
ParseState mypstate;
MemSet(&mypstate, 0, sizeof(mypstate));
mypstate.parentParseState = pstate;
mypstate.p_rtable = rte->subquery->rtable;
/* don't bother filling the rest of the fake pstate */
return expandRecordVariable(&mypstate, (Var *) expr, 0);
}
/* else fall through to inspect the expression */
}
break;
case RTE_JOIN:
/* Join RTE --- recursively inspect the alias variable */
Assert(attnum > 0 && attnum <= list_length(rte->joinaliasvars));
expr = (Node *) list_nth(rte->joinaliasvars, attnum - 1);
if (IsA(expr, Var))
return expandRecordVariable(pstate, (Var *) expr, netlevelsup);
/* else fall through to inspect the expression */
break;
case RTE_FUNCTION:
/*
* We couldn't get here unless a function is declared with one of
* its result columns as RECORD, which is not allowed.
*/
break;
case RTE_CTE:
/* CTE reference: examine subquery's output expr */
if (!rte->self_reference)
{
CommonTableExpr *cte = GetCTEForRTE(pstate, rte, netlevelsup);
TargetEntry *ste;
/* should be analyzed by now */
Assert(IsA(cte->ctequery, Query));
ste = get_tle_by_resno(((Query *) cte->ctequery)->targetList,
attnum);
if (ste == NULL || ste->resjunk)
elog(ERROR, "subquery %s does not have attribute %d",
rte->eref->aliasname, attnum);
expr = (Node *) ste->expr;
if (IsA(expr, Var))
{
/*
* Recurse into the CTE to see what its Var refers to. We
* have to build an additional level of ParseState to keep
* in step with varlevelsup in the CTE; furthermore it
* could be an outer CTE.
*/
ParseState mypstate;
Index levelsup;
MemSet(&mypstate, 0, sizeof(mypstate));
/* this loop must work, since GetCTEForRTE did */
for (levelsup = 0;
levelsup < rte->ctelevelsup + netlevelsup;
levelsup++)
pstate = pstate->parentParseState;
mypstate.parentParseState = pstate;
mypstate.p_rtable = ((Query *) cte->ctequery)->rtable;
/* don't bother filling the rest of the fake pstate */
return expandRecordVariable(&mypstate, (Var *) expr, 0);
}
/* else fall through to inspect the expression */
}
break;
}
/*
* We now have an expression we can't expand any more, so see if
* get_expr_result_type() can do anything with it. If not, pass to
* lookup_rowtype_tupdesc() which will probably fail, but will give an
* appropriate error message while failing.
*/
if (get_expr_result_type(expr, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
tupleDesc = lookup_rowtype_tupdesc_copy(exprType(expr),
exprTypmod(expr));
return tupleDesc;
}
/*
* FigureColname -
* if the name of the resulting column is not specified in the target
* list, we have to guess a suitable name. The SQL spec provides some
* guidance, but not much...
*
* Note that the argument is the *untransformed* parse tree for the target
* item. This is a shade easier to work with than the transformed tree.
*/
char *
FigureColname(Node *node)
{
char *name = NULL;
(void) FigureColnameInternal(node, &name);
if (name != NULL)
return name;
/* default result if we can't guess anything */
return "?column?";
}
/*
* FigureIndexColname -
* choose the name for an expression column in an index
*
* This is actually just like FigureColname, except we return NULL if
* we can't pick a good name.
*/
char *
FigureIndexColname(Node *node)
{
char *name = NULL;
(void) FigureColnameInternal(node, &name);
return name;
}
/*
* FigureColnameInternal -
* internal workhorse for FigureColname
*
* Return value indicates strength of confidence in result:
* 0 - no information
* 1 - second-best name choice
* 2 - good name choice
* The return value is actually only used internally.
* If the result isn't zero, *name is set to the chosen name.
*/
static int
FigureColnameInternal(Node *node, char **name)
{
int strength = 0;
if (node == NULL)
return strength;
switch (nodeTag(node))
{
case T_ColumnRef:
{
char *fname = NULL;
ListCell *l;
/* find last field name, if any, ignoring "*" */
foreach(l, ((ColumnRef *) node)->fields)
{
Node *i = lfirst(l);
if (IsA(i, String))
fname = strVal(i);
}
if (fname)
{
*name = fname;
return 2;
}
}
break;
case T_A_Indirection:
{
A_Indirection *ind = (A_Indirection *) node;
char *fname = NULL;
ListCell *l;
/* find last field name, if any, ignoring "*" and subscripts */
foreach(l, ind->indirection)
{
Node *i = lfirst(l);
if (IsA(i, String))
fname = strVal(i);
}
if (fname)
{
*name = fname;
return 2;
}
return FigureColnameInternal(ind->arg, name);
}
break;
case T_FuncCall:
*name = strVal(llast(((FuncCall *) node)->funcname));
return 2;
case T_A_Expr:
/* make nullif() act like a regular function */
if (((A_Expr *) node)->kind == AEXPR_NULLIF)
{
*name = "nullif";
return 2;
}
break;
case T_TypeCast:
strength = FigureColnameInternal(((TypeCast *) node)->arg,
name);
if (strength <= 1)
{
if (((TypeCast *) node)->typeName != NULL)
{
*name = strVal(llast(((TypeCast *) node)->typeName->names));
return 1;
}
}
break;
case T_CaseExpr:
strength = FigureColnameInternal((Node *) ((CaseExpr *) node)->defresult,
name);
if (strength <= 1)
{
*name = "case";
return 1;
}
break;
case T_A_ArrayExpr:
/* make ARRAY[] act like a function */
*name = "array";
return 2;
case T_RowExpr:
/* make ROW() act like a function */
*name = "row";
return 2;
case T_CoalesceExpr:
/* make coalesce() act like a regular function */
*name = "coalesce";
return 2;
case T_MinMaxExpr:
/* make greatest/least act like a regular function */
switch (((MinMaxExpr *) node)->op)
{
case IS_GREATEST:
*name = "greatest";
return 2;
case IS_LEAST:
*name = "least";
return 2;
}
break;
case T_XmlExpr:
/* make SQL/XML functions act like a regular function */
switch (((XmlExpr *) node)->op)
{
case IS_XMLCONCAT:
*name = "xmlconcat";
return 2;
case IS_XMLELEMENT:
*name = "xmlelement";
return 2;
case IS_XMLFOREST:
*name = "xmlforest";
return 2;
case IS_XMLPARSE:
*name = "xmlparse";
return 2;
case IS_XMLPI:
*name = "xmlpi";
return 2;
case IS_XMLROOT:
*name = "xmlroot";
return 2;
case IS_XMLSERIALIZE:
*name = "xmlserialize";
return 2;
case IS_DOCUMENT:
/* nothing */
break;
}
break;
case T_XmlSerialize:
*name = "xmlserialize";
return 2;
default:
break;
}
return strength;
}
View Git Blame Copy Permalink