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Code review for protransform patches.

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Fix loss of previous expression-simplification work when a transform
function fires: we must not simply revert to untransformed input tree.
Instead build a dummy FuncExpr node to pass to the transform function.
This has the additional advantage of providing a simpler, more uniform
API for transform functions.

Move documentation to a somewhat less buried spot, relocate some
poorly-placed code, be more wary of null constants and invalid typmod
values, add an opr_sanity check on protransform function signatures,
and some other minor cosmetic adjustments.

Note: although this patch touches pg_proc.h, no need for catversion
bump, because the changes are cosmetic and don't actually change the
intended catalog contents.
This commit is contained in:
Tom Lane
2012-03-23 17:29:57 -04:00
parent e08b4101e1
commit 0339047bc9
15 changed files with 205 additions and 172 deletions
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23
src/backend/utils/adt/numeric.c
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@ -31,7 +31,6 @@
#include "libpq/pqformat.h"
#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
#include "parser/parse_clause.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/int8.h"
@ -717,7 +716,7 @@ numeric_send(PG_FUNCTION_ARGS)
/*
* numeric_transform() -
*
* Flatten calls to our length coercion function that solely represent
* Flatten calls to numeric's length coercion function that solely represent
* increases in allowable precision. Scale changes mutate every datum, so
* they are unoptimizable. Some values, e.g. 1E-1001, can only fit into an
* unconstrained numeric, so a change from an unconstrained numeric to any
@ -727,18 +726,17 @@ Datum
numeric_transform(PG_FUNCTION_ARGS)
{
FuncExpr *expr = (FuncExpr *) PG_GETARG_POINTER(0);
Node *typmod;
Node *ret = NULL;
Node *typmod;
if (!IsA(expr, FuncExpr))
PG_RETURN_POINTER(ret);
Assert(IsA(expr, FuncExpr));
Assert(list_length(expr->args) >= 2);
Assert(list_length(expr->args) == 2);
typmod = lsecond(expr->args);
typmod = (Node *) lsecond(expr->args);
if (IsA(typmod, Const))
if (IsA(typmod, Const) && !((Const *) typmod)->constisnull)
{
Node *source = linitial(expr->args);
Node *source = (Node *) linitial(expr->args);
int32 old_typmod = exprTypmod(source);
int32 new_typmod = DatumGetInt32(((Const *) typmod)->constvalue);
int32 old_scale = (old_typmod - VARHDRSZ) & 0xffff;
@ -748,11 +746,12 @@ numeric_transform(PG_FUNCTION_ARGS)
/*
* If new_typmod < VARHDRSZ, the destination is unconstrained; that's
* always OK. If old_typmod >= VARHDRSZ, the source is constrained.
* and we're OK if the scale is unchanged and the precison is not
* always OK. If old_typmod >= VARHDRSZ, the source is constrained,
* and we're OK if the scale is unchanged and the precision is not
* decreasing. See further notes in function header comment.
*/
if (new_typmod < VARHDRSZ || (old_typmod >= VARHDRSZ &&
if (new_typmod < (int32) VARHDRSZ ||
(old_typmod >= (int32) VARHDRSZ &&
new_scale == old_scale && new_precision >= old_precision))
ret = relabel_to_typmod(source, new_typmod);
}