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Fix date_diff() bug across time zone boundaries
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Summary:
Date diff calculation for timestamp with time zone types need to be
performed in the time zone of the first parameter to follow Presto's semantic.
Timestamp calculation normalized to UTC may not return the same result if the
interval crosses a daylight savings time.

Differential Revision: D63159202
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@pedroerp @facebook-github-bot
pedroerp authored and facebook-github-bot committed Sep 21, 2024
1 parent c61a353 commit 0c7546d
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Showing 2 changed files with 99 additions and 38 deletions.
25 changes: 15 additions & 10 deletions velox/functions/prestosql/DateTimeFunctions.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1375,9 +1375,8 @@ struct DateDiffFunction : public TimestampWithTimezoneSupport<T> {
const arg_type<Varchar>& unitString,
const arg_type<Timestamp>& timestamp1,
const arg_type<Timestamp>& timestamp2) {
const auto unit = unit_.has_value()
? unit_.value()
: fromDateTimeUnitString(unitString, true /*throwIfInvalid*/).value();
const auto unit = unit_.value_or(
fromDateTimeUnitString(unitString, true /*throwIfInvalid*/).value());

if (LIKELY(sessionTimeZone_ != nullptr)) {
// sessionTimeZone not null means that the config
Expand Down Expand Up @@ -1416,13 +1415,19 @@ struct DateDiffFunction : public TimestampWithTimezoneSupport<T> {
FOLLY_ALWAYS_INLINE void call(
int64_t& result,
const arg_type<Varchar>& unitString,
const arg_type<TimestampWithTimezone>& timestamp1,
const arg_type<TimestampWithTimezone>& timestamp2) {
call(
result,
unitString,
this->toTimestamp(timestamp1, true),
this->toTimestamp(timestamp2, true));
const arg_type<TimestampWithTimezone>& timestampWithTz1,
const arg_type<TimestampWithTimezone>& timestampWithTz2) {
const auto unit = unit_.value_or(
fromDateTimeUnitString(unitString, true /*throwIfInvalid*/).value());

// Presto's behavior is to use the time zone of the first parameter to
// perform the calculation. Note that always normalizing to UTC is not
// correct as calculations may cross daylight savings boundaries.
auto timestamp1 = this->toTimestamp(timestampWithTz1, false);
auto timestamp2 = this->toTimestamp(timestampWithTz2, true);
timestamp2.toTimezone(*tz::locateZone(unpackZoneKeyId(timestampWithTz1)));

result = diffTimestamp(unit, timestamp1, timestamp2);
}
};

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112 changes: 84 additions & 28 deletions velox/functions/prestosql/tests/DateTimeFunctionsTest.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2804,62 +2804,118 @@ TEST_F(DateTimeFunctionsTest, dateDiffTimestamp) {
}

TEST_F(DateTimeFunctionsTest, dateDiffTimestampWithTimezone) {
const auto dateDiff = [&](const std::string& unit,
std::optional<int64_t> timestamp1,
const std::optional<std::string>& timeZoneName1,
std::optional<int64_t> timestamp2,
const std::optional<std::string>& timeZoneName2) {
auto ts1 = (timestamp1.has_value() && timeZoneName1.has_value())
? makeTimestampWithTimeZoneVector(
timestamp1.value(), timeZoneName1.value().c_str())
: BaseVector::createNullConstant(TIMESTAMP_WITH_TIME_ZONE(), 1, pool());
auto ts2 = (timestamp2.has_value() && timeZoneName2.has_value())
? makeTimestampWithTimeZoneVector(
timestamp2.value(), timeZoneName2.value().c_str())
: BaseVector::createNullConstant(TIMESTAMP_WITH_TIME_ZONE(), 1, pool());

const auto dateDiff = [&](std::optional<std::string> unit,
std::optional<TimestampWithTimezone> input1,
std::optional<TimestampWithTimezone> input2) {
return evaluateOnce<int64_t>(
fmt::format("date_diff('{}', c0, c1)", unit),
makeRowVector({ts1, ts2}));
"date_diff(c0, c1, c2)",
{VARCHAR(), TIMESTAMP_WITH_TIME_ZONE(), TIMESTAMP_WITH_TIME_ZONE()},
unit,
TimestampWithTimezone::pack(input1),
TimestampWithTimezone::pack(input2));
};

// Null behavior.
EXPECT_EQ(
std::nullopt,
dateDiff(
std::nullopt,
TimestampWithTimezone(0, 0),
TimestampWithTimezone(0, 0)));

EXPECT_EQ(
std::nullopt,
dateDiff("asdf", std::nullopt, TimestampWithTimezone(0, 0)));

// timestamp1: 1970-01-01 00:00:00.000 +00:00 (0)
// timestamp2: 2020-08-25 16:30:10.123 -08:00 (1'598'373'010'123)
EXPECT_EQ(
1598373010123,
dateDiff(
"millisecond",
0,
"+00:00",
1'598'373'010'123,
"America/Los_Angeles"));
TimestampWithTimezone(0, "+00:00"),
TimestampWithTimezone(1'598'373'010'123, "America/Los_Angeles")));
EXPECT_EQ(
1598373010,
dateDiff(
"second", 0, "+00:00", 1'598'373'010'123, "America/Los_Angeles"));
"second",
TimestampWithTimezone(0, "+00:00"),
TimestampWithTimezone(1'598'373'010'123, "America/Los_Angeles")));
EXPECT_EQ(
26639550,
dateDiff(
"minute", 0, "+00:00", 1'598'373'010'123, "America/Los_Angeles"));
"minute",
TimestampWithTimezone(0, "+00:00"),
TimestampWithTimezone(1'598'373'010'123, "America/Los_Angeles")));
EXPECT_EQ(
443992,
dateDiff("hour", 0, "+00:00", 1'598'373'010'123, "America/Los_Angeles"));
dateDiff(
"hour",
TimestampWithTimezone(0, "+00:00"),
TimestampWithTimezone(1'598'373'010'123, "America/Los_Angeles")));
EXPECT_EQ(
18499,
dateDiff("day", 0, "+00:00", 1'598'373'010'123, "America/Los_Angeles"));
dateDiff(
"day",
TimestampWithTimezone(0, "+00:00"),
TimestampWithTimezone(1'598'373'010'123, "America/Los_Angeles")));
EXPECT_EQ(
2642,
dateDiff("week", 0, "+00:00", 1'598'373'010'123, "America/Los_Angeles"));
dateDiff(
"week",
TimestampWithTimezone(0, "+00:00"),
TimestampWithTimezone(1'598'373'010'123, "America/Los_Angeles")));
EXPECT_EQ(
607,
dateDiff("month", 0, "+00:00", 1'598'373'010'123, "America/Los_Angeles"));
dateDiff(
"month",
TimestampWithTimezone(0, "+00:00"),
TimestampWithTimezone(1'598'373'010'123, "America/Los_Angeles")));
EXPECT_EQ(
202,
dateDiff(
"quarter", 0, "+00:00", 1'598'373'010'123, "America/Los_Angeles"));
"quarter",
TimestampWithTimezone(0, "+00:00"),
TimestampWithTimezone(1'598'373'010'123, "America/Los_Angeles")));
EXPECT_EQ(
50,
dateDiff("year", 0, "+00:00", 1'598'373'010'123, "America/Los_Angeles"));
dateDiff(
"year",
TimestampWithTimezone(0, "+00:00"),
TimestampWithTimezone(1'598'373'010'123, "America/Los_Angeles")));

// Test if calculations are being performed in correct zone. Presto behavior
// is to use the zone of the first parameter. Note that that this UTC interval
// (a, b) crosses a daylight savings boundary in PST when PST loses one hour.
// So whenever the calculation is performed in PST, the interval is
// effectively smaller than 24h and returns zero.
auto a = parseTimestamp("2024-11-02 17:00:00").toMillis();
auto b = parseTimestamp("2024-11-03 17:30:00").toMillis();
EXPECT_EQ(
1,
dateDiff(
"day",
TimestampWithTimezone(a, "UTC"),
TimestampWithTimezone(b, "America/Los_Angeles")));
EXPECT_EQ(
1,
dateDiff(
"day",
TimestampWithTimezone(a, "UTC"),
TimestampWithTimezone(b, "UTC")));

EXPECT_EQ(
0,
dateDiff(
"day",
TimestampWithTimezone(a, "America/Los_Angeles"),
TimestampWithTimezone(b, "UTC")));
EXPECT_EQ(
0,
dateDiff(
"day",
TimestampWithTimezone(a, "America/Los_Angeles"),
TimestampWithTimezone(b, "America/Los_Angeles")));
}

TEST_F(DateTimeFunctionsTest, parseDatetime) {
Expand Down

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