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Avoid unexpected conversion overflow in planner for distant date values.

author Tom Lane <tgl@sss.pgh.pa.us>

2010年12月29日 03:49:57 +0000 (22:49 -0500)

committer Tom Lane <tgl@sss.pgh.pa.us>

2010年12月29日 03:50:19 +0000 (22:50 -0500)

The "date" type supports a wider range of dates than int64 timestamps do.
However, there is pre-int64-timestamp code in the planner that assumes that
all date values can be converted to timestamp with impunity. Fortunately,
what we really need out of the conversion is always a double (float8)
value; so even when the date is out of timestamp's range it's possible to
produce a sane answer. All we need is a code path that doesn't try to
force the result into int64. Per trouble report from David Rericha.

Back-patch to all supported versions. Although this is surely a corner
case, there's not much point in advertising a date range wider than
timestamp's if we will choke on such values in unexpected places.

src/backend/utils/adt/date.c patch | blob | blame | history

src/backend/utils/adt/selfuncs.c patch | blob | blame | history

src/include/utils/date.h patch | blob | blame | history

diff --git a/src/backend/utils/adt/date.c b/src/backend/utils/adt/date.c

index b5dfe08c9bb7ab76c9173c29a55f388d7d2fe085..c97ecf4a1add9adcd14bdc682e70a41c160cbc88 100644 (file)

--- a/src/backend/utils/adt/date.c

+++ b/src/backend/utils/adt/date.c

@@ -459,6 +459,39 @@ date2timestamptz(DateADT dateVal)

return result;

}

+/*

+ * date2timestamp_no_overflow

+ *

+ * This is chartered to produce a double value that is numerically

+ * equivalent to the corresponding Timestamp value, if the date is in the

+ * valid range of Timestamps, but in any case not throw an overflow error.

+ * We can do this since the numerical range of double is greater than

+ * that of non-erroneous timestamps. The results are currently only

+ * used for statistical estimation purposes.

+ */

+double

+date2timestamp_no_overflow(DateADT dateVal)

+{

+ double result;

+

+ if (DATE_IS_NOBEGIN(dateVal))

+ result = -DBL_MAX;

+ else if (DATE_IS_NOEND(dateVal))

+ result = DBL_MAX;

+ else

+ {

+#ifdef HAVE_INT64_TIMESTAMP

+ /* date is days since 2000, timestamp is microseconds since same... */

+ result = dateVal * (double) USECS_PER_DAY;

+#else

+ /* date is days since 2000, timestamp is seconds since same... */

+ result = dateVal * (double) SECS_PER_DAY;

+#endif

+ }

+

+ return result;

+}

+

/*

* Crosstype comparison functions for dates

diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c

index 5925a91373989c16e7c0bade2028f7bb003ac7d0..c08310ba41561275c2756558a074330e8213afe9 100644 (file)

--- a/src/backend/utils/adt/selfuncs.c

+++ b/src/backend/utils/adt/selfuncs.c

@@ -3865,8 +3865,7 @@ convert_timevalue_to_scalar(Datum value, Oid typid)

return DatumGetTimestamp(DirectFunctionCall1(abstime_timestamp,

value));

case DATEOID:

- return DatumGetTimestamp(DirectFunctionCall1(date_timestamp,

- value));

+ return date2timestamp_no_overflow(DatumGetDateADT(value));

case INTERVALOID:

{

Interval *interval = DatumGetIntervalP(value);

diff --git a/src/include/utils/date.h b/src/include/utils/date.h

index 98570e663c04b41a615f6bfd7b264ff5c3d20f51..227a7c897e0dc138f0d7da46bd8326e574c77fca 100644 (file)

--- a/src/include/utils/date.h

+++ b/src/include/utils/date.h

@@ -91,6 +91,8 @@ typedef struct

/* date.c */

+extern double date2timestamp_no_overflow(DateADT dateVal);

+

extern Datum date_in(PG_FUNCTION_ARGS);

extern Datum date_out(PG_FUNCTION_ARGS);

extern Datum date_recv(PG_FUNCTION_ARGS);

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