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Enable casting of string to timestamp with microsecond resolution #3752

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merged 2 commits into from
Feb 23, 2023
Merged

Enable casting of string to timestamp with microsecond resolution #3752

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e06505b
Enable casting of string to timestamp with microsecond resolution
gruuya Feb 23, 2023
662f858
Enable string conversion to timestamp with second and millisecond res…
gruuya Feb 23, 2023
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128 changes: 101 additions & 27 deletions arrow-cast/src/cast.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -166,6 +166,9 @@ pub fn can_cast_types(from_type: &DataType, to_type: &DataType) -> bool {
| Time32(TimeUnit::Millisecond)
| Time64(TimeUnit::Microsecond)
| Time64(TimeUnit::Nanosecond)
| Timestamp(TimeUnit::Second, _)
| Timestamp(TimeUnit::Millisecond, _)
| Timestamp(TimeUnit::Microsecond, _)
| Timestamp(TimeUnit::Nanosecond, _)
) => true,
(Utf8, _) => to_type.is_numeric() && to_type != &Float16,
Expand All @@ -179,6 +182,9 @@ pub fn can_cast_types(from_type: &DataType, to_type: &DataType) -> bool {
| Time32(TimeUnit::Millisecond)
| Time64(TimeUnit::Microsecond)
| Time64(TimeUnit::Nanosecond)
| Timestamp(TimeUnit::Second, _)
| Timestamp(TimeUnit::Millisecond, _)
| Timestamp(TimeUnit::Microsecond, _)
| Timestamp(TimeUnit::Nanosecond, _)
) => true,
(LargeUtf8, _) => to_type.is_numeric() && to_type != &Float16,
Expand Down Expand Up @@ -1141,8 +1147,17 @@ pub fn cast_with_options(
Time64(TimeUnit::Nanosecond) => {
cast_string_to_time64nanosecond::<i32>(array, cast_options)
}
Timestamp(TimeUnit::Second, _) => {
cast_string_to_timestamp::<i32, TimestampSecondType>(array, cast_options)
}
Timestamp(TimeUnit::Millisecond, _) => {
cast_string_to_timestamp::<i32, TimestampMillisecondType>(array, cast_options)
}
Timestamp(TimeUnit::Microsecond, _) => {
cast_string_to_timestamp::<i32, TimestampMicrosecondType>(array, cast_options)
}
Timestamp(TimeUnit::Nanosecond, _) => {
cast_string_to_timestamp_ns::<i32>(array, cast_options)
cast_string_to_timestamp::<i32, TimestampNanosecondType>(array, cast_options)
}
_ => Err(ArrowError::CastError(format!(
"Casting from {from_type:?} to {to_type:?} not supported",
Expand Down Expand Up @@ -1182,8 +1197,17 @@ pub fn cast_with_options(
Time64(TimeUnit::Nanosecond) => {
cast_string_to_time64nanosecond::<i64>(array, cast_options)
}
Timestamp(TimeUnit::Second, _) => {
cast_string_to_timestamp::<i64, TimestampSecondType>(array, cast_options)
}
Timestamp(TimeUnit::Millisecond, _) => {
cast_string_to_timestamp::<i64, TimestampMillisecondType>(array, cast_options)
}
Timestamp(TimeUnit::Microsecond, _) => {
cast_string_to_timestamp::<i64, TimestampMicrosecondType>(array, cast_options)
}
Timestamp(TimeUnit::Nanosecond, _) => {
cast_string_to_timestamp_ns::<i64>(array, cast_options)
cast_string_to_timestamp::<i64, TimestampNanosecondType>(array, cast_options)
}
_ => Err(ArrowError::CastError(format!(
"Casting from {from_type:?} to {to_type:?} not supported",
Expand Down Expand Up @@ -2552,8 +2576,11 @@ fn cast_string_to_time64nanosecond<Offset: OffsetSizeTrait>(
Ok(Arc::new(array) as ArrayRef)
}

/// Casts generic string arrays to TimeStampNanosecondArray
fn cast_string_to_timestamp_ns<Offset: OffsetSizeTrait>(
/// Casts generic string arrays to an ArrowTimestampType (TimeStampNanosecondArray, etc.)
fn cast_string_to_timestamp<
Offset: OffsetSizeTrait,
TimestampType: ArrowTimestampType<Native = i64>,
>(
array: &dyn Array,
cast_options: &CastOptions,
) -> Result<ArrayRef, ArrowError> {
Expand All @@ -2562,26 +2589,36 @@ fn cast_string_to_timestamp_ns<Offset: OffsetSizeTrait>(
.downcast_ref::<GenericStringArray<Offset>>()
.unwrap();

let scale_factor = match TimestampType::get_time_unit() {
TimeUnit::Second => 1_000_000_000,
TimeUnit::Millisecond => 1_000_000,
TimeUnit::Microsecond => 1_000,
TimeUnit::Nanosecond => 1,
};

let array = if cast_options.safe {
let iter = string_array
.iter()
.map(|v| v.and_then(|v| string_to_timestamp_nanos(v).ok()));
let iter = string_array.iter().map(|v| {
v.and_then(|v| string_to_timestamp_nanos(v).ok().map(|t| t / scale_factor))
});
// Benefit:
// 20% performance improvement
// Soundness:
// The iterator is trustedLen because it comes from an `StringArray`.
unsafe { TimestampNanosecondArray::from_trusted_len_iter(iter) }
unsafe { PrimitiveArray::<TimestampType>::from_trusted_len_iter(iter) }
} else {
let vec = string_array
.iter()
.map(|v| v.map(string_to_timestamp_nanos).transpose())
.map(|v| {
v.map(|v| string_to_timestamp_nanos(v).map(|t| t / scale_factor))
.transpose()
})
.collect::<Result<Vec<Option<i64>>, _>>()?;

// Benefit:
// 20% performance improvement
// Soundness:
// The iterator is trustedLen because it comes from an `StringArray`.
unsafe { TimestampNanosecondArray::from_trusted_len_iter(vec.iter()) }
unsafe { PrimitiveArray::<TimestampType>::from_trusted_len_iter(vec.iter()) }
};

Ok(Arc::new(array) as ArrayRef)
Expand Down Expand Up @@ -4704,32 +4741,69 @@ mod tests {
#[test]
fn test_cast_string_to_timestamp() {
let a1 = Arc::new(StringArray::from(vec![
Some("2020-09-08T12:00:00+00:00"),
Some("2020-09-08T12:00:00.123456789+00:00"),
Some("Not a valid date"),
None,
])) as ArrayRef;
let a2 = Arc::new(LargeStringArray::from(vec![
Some("2020-09-08T12:00:00+00:00"),
Some("2020-09-08T12:00:00.123456789+00:00"),
Some("Not a valid date"),
None,
])) as ArrayRef;
for array in &[a1, a2] {
let to_type = DataType::Timestamp(TimeUnit::Nanosecond, None);
let b = cast(array, &to_type).unwrap();
let c = b
.as_any()
.downcast_ref::<TimestampNanosecondArray>()
.unwrap();
assert_eq!(1599566400000000000, c.value(0));
assert!(c.is_null(1));
assert!(c.is_null(2));
for time_unit in &[
TimeUnit::Second,
TimeUnit::Millisecond,
TimeUnit::Microsecond,
TimeUnit::Nanosecond,
] {
let to_type = DataType::Timestamp(time_unit.clone(), None);
let b = cast(array, &to_type).unwrap();

match time_unit {
TimeUnit::Second => {
let c =
b.as_any().downcast_ref::<TimestampSecondArray>().unwrap();
assert_eq!(1599566400, c.value(0));
assert!(c.is_null(1));
assert!(c.is_null(2));
}
TimeUnit::Millisecond => {
let c = b
.as_any()
.downcast_ref::<TimestampMillisecondArray>()
.unwrap();
assert_eq!(1599566400123, c.value(0));
assert!(c.is_null(1));
assert!(c.is_null(2));
}
TimeUnit::Microsecond => {
let c = b
.as_any()
.downcast_ref::<TimestampMicrosecondArray>()
.unwrap();
assert_eq!(1599566400123456, c.value(0));
assert!(c.is_null(1));
assert!(c.is_null(2));
}
TimeUnit::Nanosecond => {
let c = b
.as_any()
.downcast_ref::<TimestampNanosecondArray>()
.unwrap();
assert_eq!(1599566400123456789, c.value(0));
assert!(c.is_null(1));
assert!(c.is_null(2));
}
}

let options = CastOptions { safe: false };
let err = cast_with_options(array, &to_type, &options).unwrap_err();
assert_eq!(
err.to_string(),
"Cast error: Error parsing 'Not a valid date' as timestamp"
);
let options = CastOptions { safe: false };
let err = cast_with_options(array, &to_type, &options).unwrap_err();
assert_eq!(
err.to_string(),
"Cast error: Error parsing 'Not a valid date' as timestamp"
);
}
}
}

Expand Down