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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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29
src/backend/utils/adt/datetime.c
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@ -24,7 +24,6 @@
#include "funcapi.h"
#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
#include "parser/parse_clause.h"
#include "utils/builtins.h"
#include "utils/date.h"
#include "utils/datetime.h"
@ -4153,32 +4152,34 @@ CheckDateTokenTables(void)
}
/*
* Helper for temporal protransform functions. Types time, timetz, timestamp
* and timestamptz each have a range of allowed precisions. An unspecified
* precision is rigorously equivalent to the highest specifiable precision.
* Common code for temporal protransform functions. Types time, timetz,
* timestamp and timestamptz each have a range of allowed precisions. An
* unspecified precision is rigorously equivalent to the highest specifiable
* precision.
*
* Note: timestamp_scale throws an error when the typmod is out of range, but
* we can't get there from a cast: our typmodin will have caught it already.
*/
Node *
TemporalTransform(int32 max_precis, Node *node)
{
FuncExpr *expr = (FuncExpr *) node;
Node *typmod;
Node *ret = NULL;
Node *typmod;
if (!IsA(expr, FuncExpr))
return 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_precis = exprTypmod(source);
int32 new_precis = DatumGetInt32(((Const *) typmod)->constvalue);
if (new_precis == -1 ||
new_precis == max_precis ||
(old_precis != -1 && new_precis >= old_precis))
if (new_precis < 0 || new_precis == max_precis ||
(old_precis >= 0 && new_precis >= old_precis))
ret = relabel_to_typmod(source, new_precis);
}