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Fix interval_transform so it doesn't throw away non-no-op casts.

Browse Source 
interval_transform() contained two separate bugs that caused it to
sometimes mistakenly decide that a cast from interval to restricted
interval is a no-op and throw it away.

First, it was wrong to rely on dt.h's field type macros to have an
ordering consistent with the field's significance; in one case they do
not.  This led to mistakenly treating YEAR as less significant than MONTH,
so that a cast from INTERVAL MONTH to INTERVAL YEAR was incorrectly
discarded.

Second, fls(1<<k) produces k+1 not k, so comparing its output directly
to SECOND was wrong.  This led to supposing that a cast to INTERVAL
MINUTE was really a cast to INTERVAL SECOND and so could be discarded.

To fix, get rid of the use of fls(), and make a function based on
intervaltypmodout to produce a field ID code adapted to the need here.

Per bug #14479 from Piotr Stefaniak.  Back-patch to 9.2 where transform
functions were introduced, because this code was born broken.

Discussion: https://postgr.es/m/20161227172307.10135.7747@wrigleys.postgresql.org
This commit is contained in:
Tom Lane
2016-12-27 15:43:54 -05:00
parent f60daa3bdc
commit 5835998390
3 changed files with 104 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

103
src/backend/utils/adt/timestamp.c
View File

@@ -922,6 +922,59 @@ intervaltypmodout(PG_FUNCTION_ARGS)
PG_RETURN_CSTRING(res);
}
/*
* Given an interval typmod value, return a code for the least-significant
* field that the typmod allows to be nonzero, for instance given
* INTERVAL DAY TO HOUR we want to identify "hour".
*
* The results should be ordered by field significance, which means
* we can't use the dt.h macros YEAR etc, because for some odd reason
* they aren't ordered that way. Instead, arbitrarily represent
* SECOND = 0, MINUTE = 1, HOUR = 2, DAY = 3, MONTH = 4, YEAR = 5.
*/
static int
intervaltypmodleastfield(int32 typmod)
{
if (typmod < 0)
return 0; /* SECOND */
switch (INTERVAL_RANGE(typmod))
{
case INTERVAL_MASK(YEAR):
return 5; /* YEAR */
case INTERVAL_MASK(MONTH):
return 4; /* MONTH */
case INTERVAL_MASK(DAY):
return 3; /* DAY */
case INTERVAL_MASK(HOUR):
return 2; /* HOUR */
case INTERVAL_MASK(MINUTE):
return 1; /* MINUTE */
case INTERVAL_MASK(SECOND):
return 0; /* SECOND */
case INTERVAL_MASK(YEAR) | INTERVAL_MASK(MONTH):
return 4; /* MONTH */
case INTERVAL_MASK(DAY) | INTERVAL_MASK(HOUR):
return 2; /* HOUR */
case INTERVAL_MASK(DAY) | INTERVAL_MASK(HOUR) | INTERVAL_MASK(MINUTE):
return 1; /* MINUTE */
case INTERVAL_MASK(DAY) | INTERVAL_MASK(HOUR) | INTERVAL_MASK(MINUTE) | INTERVAL_MASK(SECOND):
return 0; /* SECOND */
case INTERVAL_MASK(HOUR) | INTERVAL_MASK(MINUTE):
return 1; /* MINUTE */
case INTERVAL_MASK(HOUR) | INTERVAL_MASK(MINUTE) | INTERVAL_MASK(SECOND):
return 0; /* SECOND */
case INTERVAL_MASK(MINUTE) | INTERVAL_MASK(SECOND):
return 0; /* SECOND */
case INTERVAL_FULL_RANGE:
return 0; /* SECOND */
default:
elog(ERROR, "invalid INTERVAL typmod: 0x%x", typmod);
break;
}
return 0; /* can't get here, but keep compiler quiet */
}
/* interval_transform()
* Flatten superfluous calls to interval_scale(). The interval typmod is
@@ -943,39 +996,39 @@ interval_transform(PG_FUNCTION_ARGS)
if (IsA(typmod, Const) &&!((Const *) typmod)->constisnull)
{
Node *source = (Node *) linitial(expr->args);
int32 old_typmod = exprTypmod(source);
int32 new_typmod = DatumGetInt32(((Const *) typmod)->constvalue);
int old_range;
int old_precis;
int new_range = INTERVAL_RANGE(new_typmod);
int new_precis = INTERVAL_PRECISION(new_typmod);
int new_range_fls;
int old_range_fls;
bool noop;
if (old_typmod < 0)
{
old_range = INTERVAL_FULL_RANGE;
old_precis = INTERVAL_FULL_PRECISION;
}
if (new_typmod < 0)
noop = true;
else
{
old_range = INTERVAL_RANGE(old_typmod);
int32 old_typmod = exprTypmod(source);
int old_least_field;
int new_least_field;
int old_precis;
int new_precis;
old_least_field = intervaltypmodleastfield(old_typmod);
new_least_field = intervaltypmodleastfield(new_typmod);
if (old_typmod < 0)
old_precis = INTERVAL_FULL_PRECISION;
else
old_precis = INTERVAL_PRECISION(old_typmod);
}
new_precis = INTERVAL_PRECISION(new_typmod);
/*
* Temporally-smaller fields occupy higher positions in the range
* bitmap. Since only the temporally-smallest bit matters for length
* coercion purposes, we compare the last-set bits in the ranges.
* Precision, which is to say, sub-second precision, only affects
* ranges that include SECOND.
* Cast is a no-op if least field stays the same or decreases
* while precision stays the same or increases. But precision,
* which is to say, sub-second precision, only affects ranges that
* include SECOND.
*/
new_range_fls = fls(new_range);
old_range_fls = fls(old_range);
if (new_typmod < 0 ||
((new_range_fls >= SECOND || new_range_fls >= old_range_fls) &&
(old_range_fls < SECOND || new_precis >= MAX_INTERVAL_PRECISION ||
new_precis >= old_precis)))
noop = (new_least_field <= old_least_field) &&
(old_least_field > 0 /* SECOND */ ||
new_precis >= MAX_INTERVAL_PRECISION ||
new_precis >= old_precis);
}
if (noop)
ret = relabel_to_typmod(source, new_typmod);
}

18
src/test/regress/expected/interval.out
View File

@@ -692,6 +692,24 @@ SELECT interval '1 2:03:04.5678' minute to second(2);
1 day 02:03:04.57
(1 row)
-- test casting to restricted precision (bug #14479)
SELECT f1, f1::INTERVAL DAY TO MINUTE AS "minutes",
(f1 + INTERVAL '1 month')::INTERVAL MONTH::INTERVAL YEAR AS "years"
FROM interval_tbl;
f1 | minutes | years
-----------------+-----------------+----------
00:01:00 | 00:01:00 | 00:00:00
05:00:00 | 05:00:00 | 00:00:00
10 days | 10 days | 00:00:00
34 years | 34 years | 34 years
3 mons | 3 mons | 00:00:00
-00:00:14 | 00:00:00 | 00:00:00
1 day 02:03:04 | 1 day 02:03:00 | 00:00:00
6 years | 6 years | 6 years
5 mons | 5 mons | 00:00:00
5 mons 12:00:00 | 5 mons 12:00:00 | 00:00:00
(10 rows)
-- test inputting and outputting SQL standard interval literals
SET IntervalStyle TO sql_standard;
SELECT interval '0' AS "zero",

5
src/test/regress/sql/interval.sql
View File

@@ -198,6 +198,11 @@ SELECT interval '1 2.3456' minute to second(2);
SELECT interval '1 2:03.5678' minute to second(2);
SELECT interval '1 2:03:04.5678' minute to second(2);
-- test casting to restricted precision (bug #14479)
SELECT f1, f1::INTERVAL DAY TO MINUTE AS "minutes",
(f1 + INTERVAL '1 month')::INTERVAL MONTH::INTERVAL YEAR AS "years"
FROM interval_tbl;
-- test inputting and outputting SQL standard interval literals
SET IntervalStyle TO sql_standard;
SELECT interval '0' AS "zero",