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Add default expressions to INSERTs during planning, not during parse

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analysis.  This keeps stored rules from prematurely absorbing default
information, which is necessary for ALTER TABLE SET DEFAULT to work
unsurprisingly with rules.  See pgsql-bugs discussion 24-Oct-01.
This commit is contained in:
Tom Lane
2001-11-02 20:23:02 +00:00
parent a9b6691ae7
commit 9685afb0b2
3 changed files with 161 additions and 135 deletions
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229
src/backend/optimizer/prep/preptlist.c
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@@ -15,7 +15,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/preptlist.c,v 1.44 2001/10/25 05:49:33 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/preptlist.c,v 1.45 2001/11/02 20:23:02 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -27,6 +27,10 @@
#include "nodes/makefuncs.h"
#include "optimizer/prep.h"
#include "parser/parsetree.h"
#include "parser/parse_coerce.h"
#include "parser/parse_expr.h"
#include "parser/parse_target.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
@@ -35,6 +39,7 @@ static List *expand_targetlist(List *tlist, int command_type,
static TargetEntry *process_matched_tle(TargetEntry *src_tle,
TargetEntry *prior_tle,
int attrno);
static Node *build_column_default(Relation rel, int attrno);
/*
@@ -168,6 +173,7 @@ expand_targetlist(List *tlist, int command_type,
{
new_tle = process_matched_tle(old_tle, new_tle, attrno);
tlistentry_used[old_tlist_index] = true;
/* keep scanning to detect multiple assignments to attr */
}
old_tlist_index++;
}
@@ -177,97 +183,44 @@ expand_targetlist(List *tlist, int command_type,
/*
* Didn't find a matching tlist entry, so make one.
*
* For INSERT, generate a constant of the default value for the
* attribute type, or NULL if no default value.
* For INSERT, generate an appropriate default value.
*
* For UPDATE, generate a Var reference to the existing value of
* the attribute, so that it gets copied to the new tuple.
*/
Oid atttype = att_tup->atttypid;
int32 atttypmod = att_tup->atttypmod;
Node *new_expr;
switch (command_type)
{
case CMD_INSERT:
{
bool hasdefault;
Datum typedefault;
int16 typlen;
bool typbyval;
Const *def_const;
if (att_tup->attisset)
{
/*
* Set attributes are represented as OIDs no
* matter what the set element type is, and
* the element type's default is irrelevant
* too.
*/
hasdefault = false;
typedefault = (Datum) 0;
typlen = sizeof(Oid);
typbyval = true;
}
else
{
#ifdef _DROP_COLUMN_HACK__
if (COLUMN_IS_DROPPED(att_tup))
{
hasdefault = false;
typedefault = (Datum) 0;
}
else
#endif /* _DROP_COLUMN_HACK__ */
hasdefault = get_typdefault(atttype,
&typedefault);
get_typlenbyval(atttype, &typlen, &typbyval);
}
def_const = makeConst(atttype,
typlen,
typedefault,
!hasdefault,
typbyval,
false, /* not a set */
false);
new_tle = makeTargetEntry(makeResdom(attrno,
atttype,
-1,
pstrdup(attrname),
false),
(Node *) def_const);
break;
}
new_expr = build_column_default(rel, attrno);
break;
case CMD_UPDATE:
{
Var *temp_var;
#ifdef _DROP_COLUMN_HACK__
if (COLUMN_IS_DROPPED(att_tup))
temp_var = (Var *) makeNullConst(atttype);
else
if (COLUMN_IS_DROPPED(att_tup))
new_expr = (Node *) makeNullConst(atttype);
else
#endif /* _DROP_COLUMN_HACK__ */
temp_var = makeVar(result_relation,
attrno,
atttype,
atttypmod,
0);
new_tle = makeTargetEntry(makeResdom(attrno,
atttype,
atttypmod,
pstrdup(attrname),
false),
(Node *) temp_var);
break;
}
new_expr = (Node *) makeVar(result_relation,
attrno,
atttype,
atttypmod,
0);
break;
default:
elog(ERROR, "expand_targetlist: unexpected command_type");
new_expr = NULL; /* keep compiler quiet */
break;
}
new_tle = makeTargetEntry(makeResdom(attrno,
atttype,
atttypmod,
pstrdup(attrname),
false),
new_expr);
}
new_tlist = lappend(new_tlist, new_tle);
@@ -385,3 +338,129 @@ process_matched_tle(TargetEntry *src_tle,
resdom->resno = attrno;
return makeTargetEntry(resdom, (Node *) newexpr);
}
/*
* Make an expression tree for the default value for a column.
*
* This is used to fill in missing attributes in an INSERT targetlist.
* We look first to see if the column has a default value expression.
* If not, generate a constant of the default value for the attribute type,
* or a NULL if the type has no default value either.
*/
static Node *
build_column_default(Relation rel, int attrno)
{
TupleDesc rd_att = rel->rd_att;
Form_pg_attribute att_tup = rd_att->attrs[attrno - 1];
Oid atttype = att_tup->atttypid;
int32 atttypmod = att_tup->atttypmod;
bool hasdefault;
Datum typedefault;
int16 typlen;
bool typbyval;
Node *expr;
/*
* Scan to see if relation has a default for this column.
*/
if (rd_att->constr && rd_att->constr->num_defval > 0)
{
AttrDefault *defval = rd_att->constr->defval;
int ndef = rd_att->constr->num_defval;
while (--ndef >= 0)
{
if (attrno == defval[ndef].adnum)
{
Oid type_id;
/*
* Found it, convert string representation to node tree.
*/
expr = stringToNode(defval[ndef].adbin);
/*
* Make sure the value is coerced to the target column type
* (might not be right type yet if it's not a constant!)
* This should match the parser's processing of non-defaulted
* expressions --- see updateTargetListEntry().
*/
type_id = exprType(expr);
if (type_id != atttype)
{
expr = CoerceTargetExpr(NULL, expr, type_id,
atttype, atttypmod);
/*
* This really shouldn't fail; should have checked the
* default's type when it was created ...
*/
if (expr == NULL)
elog(ERROR, "Column \"%s\" is of type %s"
" but default expression is of type %s"
"\n\tYou will need to rewrite or cast the expression",
NameStr(att_tup->attname),
format_type_be(atttype),
format_type_be(type_id));
}
/*
* If the column is a fixed-length type, it may need a
* length coercion as well as a type coercion.
*/
expr = coerce_type_typmod(NULL, expr,
atttype, atttypmod);
return expr;
}
}
}
/*
* No per-column default, so look for a default for the type itself.
* If there isn't one, we generate a NULL constant of the correct type.
*/
if (att_tup->attisset)
{
/*
* Set attributes are represented as OIDs no matter what the set
* element type is, and the element type's default is irrelevant too.
*/
hasdefault = false;
typedefault = (Datum) 0;
typlen = sizeof(Oid);
typbyval = true;
}
else
{
#ifdef _DROP_COLUMN_HACK__
if (COLUMN_IS_DROPPED(att_tup))
{
hasdefault = false;
typedefault = (Datum) 0;
}
else
#endif /* _DROP_COLUMN_HACK__ */
hasdefault = get_typdefault(atttype, &typedefault);
get_typlenbyval(atttype, &typlen, &typbyval);
}
expr = (Node *) makeConst(atttype,
typlen,
typedefault,
!hasdefault,
typbyval,
false, /* not a set */
false);
/*
* If the column is a fixed-length type, it may need a length coercion
* as well as a type coercion. But NULLs don't need that.
*/
if (hasdefault)
expr = coerce_type_typmod(NULL, expr,
atttype, atttypmod);
return expr;
}