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Merged
alamb merged 5 commits into from
Mar 31, 2025
Merged

Decimal type support for to_timestamp #15486

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73a26e9
wip: decimal type support for to_timestamp
jatin510 Mar 29, 2025
4232fc1
updated timestamp handling for cast operator
jatin510 Mar 29, 2025
ec672d6
fixed clippy error
jatin510 Mar 29, 2025
ac1f430
fixed fmt
jatin510 Mar 29, 2025
bd5f242
updated timestamps.slt file for decimal128 type support
jatin510 Mar 29, 2025
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28 changes: 28 additions & 0 deletions datafusion/common/src/scalar/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3036,6 +3036,34 @@ impl ScalarValue {
DataType::Timestamp(TimeUnit::Nanosecond, None),
) => ScalarValue::Int64(Some((float_ts * 1_000_000_000_f64).trunc() as i64))
.to_array()?,
(
ScalarValue::Decimal128(Some(decimal_value), _, scale),
DataType::Timestamp(time_unit, None),
) => {
let scale_factor = 10_i128.pow(*scale as u32);
let seconds = decimal_value / scale_factor;
let fraction = decimal_value % scale_factor;

let timestamp_value = match time_unit {
TimeUnit::Second => ScalarValue::Int64(Some(seconds as i64)),
TimeUnit::Millisecond => {
let millis = seconds * 1_000 + (fraction * 1_000) / scale_factor;
ScalarValue::Int64(Some(millis as i64))
}
TimeUnit::Microsecond => {
let micros =
seconds * 1_000_000 + (fraction * 1_000_000) / scale_factor;
ScalarValue::Int64(Some(micros as i64))
}
TimeUnit::Nanosecond => {
let nanos = seconds * 1_000_000_000
+ (fraction * 1_000_000_000) / scale_factor;
ScalarValue::Int64(Some(nanos as i64))
}
};

timestamp_value.to_array()?
}
_ => self.to_array()?,
};

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31 changes: 27 additions & 4 deletions datafusion/functions/src/datetime/to_timestamp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,15 +18,14 @@
use std::any::Any;
use std::sync::Arc;

use crate::datetime::common::*;
use arrow::datatypes::DataType::*;
use arrow::datatypes::TimeUnit::{Microsecond, Millisecond, Nanosecond, Second};
use arrow::datatypes::{
ArrowTimestampType, DataType, TimeUnit, TimestampMicrosecondType,
TimestampMillisecondType, TimestampNanosecondType, TimestampSecondType,
};

use crate::datetime::common::*;
use datafusion_common::{exec_err, Result, ScalarType};
use datafusion_common::{exec_err, Result, ScalarType, ScalarValue};
use datafusion_expr::{
ColumnarValue, Documentation, ScalarUDFImpl, Signature, Volatility,
};
Expand Down Expand Up @@ -329,6 +328,30 @@ impl ScalarUDFImpl for ToTimestampFunc {
Utf8View | LargeUtf8 | Utf8 => {
to_timestamp_impl::<TimestampNanosecondType>(&args, "to_timestamp")
}
Decimal128(_, _) => {
match &args[0] {
ColumnarValue::Scalar(ScalarValue::Decimal128(
Some(value),
_,
scale,
)) => {
// Convert decimal to seconds and nanoseconds
let scale_factor = 10_i128.pow(*scale as u32);
let seconds = value / scale_factor;
let fraction = value % scale_factor;

let nanos = (fraction * 1_000_000_000) / scale_factor;

let timestamp_nanos = seconds * 1_000_000_000 + nanos;

Ok(ColumnarValue::Scalar(ScalarValue::TimestampNanosecond(
Some(timestamp_nanos as i64),
None,
)))
}
_ => exec_err!("Invalid decimal value"),
}
}
other => {
exec_err!(
"Unsupported data type {:?} for function to_timestamp",
Expand Down Expand Up @@ -377,7 +400,7 @@ impl ScalarUDFImpl for ToTimestampSecondsFunc {
}

match args[0].data_type() {
Null | Int32 | Int64 | Timestamp(_, None) => {
Null | Int32 | Int64 | Timestamp(_, None) | Decimal128(_, _) => {
args[0].cast_to(&Timestamp(Second, None), None)
}
Timestamp(_, Some(tz)) => args[0].cast_to(&Timestamp(Second, Some(tz)), None),
Expand Down
27 changes: 27 additions & 0 deletions datafusion/sqllogictest/test_files/timestamps.slt
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Original file line number Diff line number Diff line change
Expand Up @@ -416,6 +416,33 @@ SELECT to_timestamp(123456789.123456789) as c1, cast(123456789.123456789 as time
----
1973-11-29T21:33:09.123456784 1973-11-29T21:33:09.123456784 1973-11-29T21:33:09.123456784

# to_timestamp Decimal128 inputs

query PPP
SELECT to_timestamp(arrow_cast(1.1, 'Decimal128(2,1)')) as c1, cast(arrow_cast(1.1, 'Decimal128(2,1)') as timestamp) as c2, arrow_cast(1.1, 'Decimal128(2,1)')::timestamp as c3;
----
1970-01-01T00:00:01.100 1970-01-01T00:00:01.100 1970-01-01T00:00:01.100

query PPP
SELECT to_timestamp(arrow_cast(-1.1, 'Decimal128(2,1)')) as c1, cast(arrow_cast(-1.1, 'Decimal128(2,1)') as timestamp) as c2, arrow_cast(-1.1, 'Decimal128(2,1)')::timestamp as c3;
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@alamb alamb Mar 30, 2025

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what is the value of computing the same value 3 times?

Perhaps it would make more sense to use different types with the same value to show the timestamp that comes back is the same and consistent?

Suggested change
SELECT to_timestamp(arrow_cast(-1.1, 'Decimal128(2,1)')) as c1, cast(arrow_cast(-1.1, 'Decimal128(2,1)') as timestamp) as c2, arrow_cast(-1.1, 'Decimal128(2,1)')::timestamp as c3;
SELECT to_timestamp(arrow_cast(-1.1, 'Int64')) as c1, cast(arrow_cast(-1.1, 'Decimal128(2,1)') as timestamp) as c2, arrow_cast(-1.1, 'Decimal128(9,8)')::timestamp as c3;

(and similarly for the other tests)

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@jatin510 jatin510 Mar 30, 2025

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I took reference from other tests, and what i can check is that it shows different way of executing to_timestamp

  • to_timestamp(value) uses the UDF (User Defined Function) implementation in to_timestamp.rs
  • CAST(value AS TIMESTAMP) or equivalently value AS TIMESTAMP uses DataFusion's casting system which relies on Arrow's cast kernels
  • value::TIMESTAMP is SQL syntax sugar for CAST, and uses the same casting route as option 2

----
1969-12-31T23:59:58.900 1969-12-31T23:59:58.900 1969-12-31T23:59:58.900

query PPP
SELECT to_timestamp(arrow_cast(0.0, 'Decimal128(2,1)')) as c1, cast(arrow_cast(0.0, 'Decimal128(2,1)') as timestamp) as c2, arrow_cast(0.0, 'Decimal128(2,1)')::timestamp as c3;
----
1970-01-01T00:00:00 1970-01-01T00:00:00 1970-01-01T00:00:00

query PPP
SELECT to_timestamp(arrow_cast(1.23456789, 'Decimal128(9,8)')) as c1, cast(arrow_cast(1.23456789, 'Decimal128(9,8)') as timestamp) as c2, arrow_cast(1.23456789, 'Decimal128(9,8)')::timestamp as c3;
----
1970-01-01T00:00:01.234567890 1970-01-01T00:00:01.234567890 1970-01-01T00:00:01.234567890

query PPP
SELECT to_timestamp(arrow_cast(123456789.123456789, 'Decimal128(18,9)')) as c1, cast(arrow_cast(123456789.123456789, 'Decimal128(18,9)') as timestamp) as c2, arrow_cast(123456789.123456789, 'Decimal128(18,9)')::timestamp as c3;
----
1973-11-29T21:33:09.123456784 1973-11-29T21:33:09.123456784 1973-11-29T21:33:09.123456784


# from_unixtime

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