rdelaage/postgresql
1
0
Fork 0
mirror of https://git.postgresql.org/git/postgresql.git synced 2024-08-29 11:27:20 +02:00
Code Issues Packages Projects Releases Wiki Activity
e18e8f8735
postgresql/src/backend/parser/parse_target.c
Tom Lane e18e8f8735 Change expandRTE() and ResolveNew() back to taking just the single 
RTE of interest, rather than the whole rangetable list.  This makes
the API more understandable and avoids duplicate RTE lookups.  This
patch reverts no-longer-needed portions of my patch of 2004-08-19.
2005-06-04 19:19:42 +00:00

1152 lines
30 KiB
C
Raw Blame History

/*-------------------------------------------------------------------------
*
* parse_target.c
* handle target lists
*
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/parser/parse_target.c,v 1.135 2005/06/04 19:19:42 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "commands/dbcommands.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "nodes/bitmapset.h"
#include "nodes/makefuncs.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);
static List *ExpandColumnRefStar(ParseState *pstate, ColumnRef *cref);
static List *ExpandAllTables(ParseState *pstate);
static List *ExpandIndirectionStar(ParseState *pstate, A_Indirection *ind);
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 name in
* ColumnRef, or as the last indirection item in A_Indirection.
*/
if (IsA(res->val, ColumnRef))
{
ColumnRef *cref = (ColumnRef *) res->val;
if (strcmp(strVal(llast(cref->fields)), "*") == 0)
{
/* It is something.*, expand into multiple items */
p_target = list_concat(p_target,
ExpandColumnRefStar(pstate, cref));
continue;
}
}
else if (IsA(res->val, A_Indirection))
{
A_Indirection *ind = (A_Indirection *) res->val;
Node *lastitem = llast(ind->indirection);
if (IsA(lastitem, String) &&
strcmp(strVal(lastitem), "*") == 0)
{
/* It is something.*, expand into multiple items */
p_target = list_concat(p_target,
ExpandIndirectionStar(pstate, ind));
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;
}
/*
* 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:
/* not a simple relation, leave it unmarked */
break;
}
}
/*
* updateTargetListEntry()
* This is used in INSERT and UPDATE statements only. It prepares a
* 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
*/
void
updateTargetListEntry(ParseState *pstate,
TargetEntry *tle,
char *colname,
int attrno,
List *indirection)
{
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)));
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 (tle->expr && IsA(tle->expr, SetToDefault))
{
SetToDefault *def = (SetToDefault *) tle->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")));
else
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot set a subfield to DEFAULT")));
}
}
/* Now we can use exprType() safely. */
type_id = exprType((Node *) tle->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);
}
else
{
/*
* Build a Var for the column to be updated.
*/
colVar = (Node *) make_var(pstate,
pstate->p_target_rangetblentry,
attrno);
}
tle->expr = (Expr *)
transformAssignmentIndirection(pstate,
colVar,
colname,
false,
attrtype,
attrtypmod,
list_head(indirection),
(Node *) tle->expr);
}
else
{
/*
* For normal non-qualified target column, do type checking and
* coercion.
*/
tle->expr = (Expr *)
coerce_to_target_type(pstate,
(Node *) tle->expr, type_id,
attrtype, attrtypmod,
COERCION_ASSIGNMENT,
COERCE_IMPLICIT_CAST);
if (tle->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.")));
}
/*
* 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.
*/
static Node *
transformAssignmentIndirection(ParseState *pstate,
Node *basenode,
const char *targetName,
bool targetIsArray,
Oid targetTypeId,
int32 targetTypMod,
ListCell *indirection,
Node *rhs)
{
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
{
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);
/* 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))));
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))));
if (attnum < 0)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_COLUMN),
errmsg("cannot assign to system column \"%s\"",
strVal(n))));
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);
/* 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);
/* 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);
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.")));
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.")));
}
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;
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);
/*
* 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)));
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)));
partialcols = bms_add_member(partialcols, attrno);
}
*attrnos = lappend_int(*attrnos, attrno);
}
}
return cols;
}
/*
* ExpandColumnRefStar()
* Turns foo.* (in the target list) into a list of targetlist entries.
*
* This handles the case where '*' appears as the last or only name in a
* ColumnRef.
*/
static List *
ExpandColumnRefStar(ParseState *pstate, ColumnRef *cref)
{
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)
*/
return ExpandAllTables(pstate);
}
else
{
/*
* Target item is relation.*, expand that table
*
* (e.g., SELECT emp.*, dname FROM emp, dept)
*/
char *schemaname;
char *relname;
RangeTblEntry *rte;
int sublevels_up;
int rtindex;
switch (numnames)
{
case 2:
schemaname = NULL;
relname = strVal(linitial(fields));
break;
case 3:
schemaname = strVal(linitial(fields));
relname = strVal(lsecond(fields));
break;
case 4:
{
char *name1 = strVal(linitial(fields));
/*
* We check the catalog name and then ignore it.
*/
if (strcmp(name1, get_database_name(MyDatabaseId)) != 0)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cross-database references are not implemented: %s",
NameListToString(fields))));
schemaname = strVal(lsecond(fields));
relname = strVal(lthird(fields));
break;
}
default:
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("improper qualified name (too many dotted names): %s",
NameListToString(fields))));
schemaname = NULL; /* keep compiler quiet */
relname = NULL;
break;
}
rte = refnameRangeTblEntry(pstate, schemaname, relname,
&sublevels_up);
if (rte == NULL)
rte = addImplicitRTE(pstate, makeRangeVar(schemaname,
relname));
rtindex = RTERangeTablePosn(pstate, rte, &sublevels_up);
return expandRelAttrs(pstate, rte, rtindex, sublevels_up);
}
}
/*
* ExpandAllTables()
* Turns '*' (in the target list) into a list of targetlist entries.
*
* tlist entries are generated for each relation appearing at the top level
* of the query's namespace, except for RTEs marked not inFromCl. (These
* may include NEW/OLD pseudo-entries, implicit RTEs, etc.)
*/
static List *
ExpandAllTables(ParseState *pstate)
{
List *target = NIL;
bool found_table = false;
ListCell *ns;
foreach(ns, pstate->p_namespace)
{
Node *n = (Node *) lfirst(ns);
int rtindex;
RangeTblEntry *rte;
if (IsA(n, RangeTblRef))
rtindex = ((RangeTblRef *) n)->rtindex;
else if (IsA(n, JoinExpr))
rtindex = ((JoinExpr *) n)->rtindex;
else
{
elog(ERROR, "unrecognized node type: %d", (int) nodeTag(n));
rtindex = 0; /* keep compiler quiet */
}
/*
* Ignore added-on relations that were not listed in the FROM
* clause.
*/
rte = rt_fetch(rtindex, pstate->p_rtable);
if (!rte->inFromCl)
continue;
found_table = true;
target = list_concat(target,
expandRelAttrs(pstate, rte, rtindex, 0));
}
/* Check for SELECT *; */
if (!found_table)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("SELECT * with no tables specified is not valid")));
return target;
}
/*
* ExpandIndirectionStar()
* Turns foo.* (in the target list) into a list of targetlist entries.
*
* This handles the case where '*' appears as the last item in A_Indirection.
*/
static List *
ExpandIndirectionStar(ParseState *pstate, A_Indirection *ind)
{
Node *expr;
TupleDesc tupleDesc;
int numAttrs;
int i;
List *te_list = NIL;
/* 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);
/*
* 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(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];
Node *fieldnode;
TargetEntry *te;
if (att->attisdropped)
continue;
/*
* If we got a whole-row Var from the rowtype reference, we can
* expand the fields as simple Vars. Otherwise we must generate
* multiple copies of the rowtype reference and do FieldSelects.
*/
if (IsA(expr, Var) &&
((Var *) expr)->varattno == InvalidAttrNumber)
{
Var *var = (Var *) expr;
fieldnode = (Node *) makeVar(var->varno,
i + 1,
att->atttypid,
att->atttypmod,
var->varlevelsup);
}
else
{
FieldSelect *fselect = makeNode(FieldSelect);
fselect->arg = (Expr *) copyObject(expr);
fselect->fieldnum = i + 1;
fselect->resulttype = att->atttypid;
fselect->resulttypmod = att->atttypmod;
fieldnode = (Node *) fselect;
}
te = makeTargetEntry((Expr *) fieldnode,
(AttrNumber) pstate->p_next_resno++,
pstrdup(NameStr(att->attname)),
false);
te_list = lappend(te_list, te);
}
return te_list;
}
/*
* 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, 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:
/*
* This case should not occur: a column of a table 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;
}
/*
* 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(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;
FigureColnameInternal(node, &name);
if (name != NULL)
return name;
/* default result if we can't guess anything */
return "?column?";
}
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 (strcmp(strVal(i), "*") != 0)
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 "*" */
foreach(l, ind->indirection)
{
Node *i = lfirst(l);
if (IsA(i, String) &&
strcmp(strVal(i), "*") != 0)
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_A_Const:
if (((A_Const *) node)->typename != NULL)
{
*name = strVal(llast(((A_Const *) node)->typename->names));
return 1;
}
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_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;
default:
break;
}
return strength;
}
Reference in New Issue View Git Blame Copy Permalink