restore to_timestamp(double) behavior

the function was not meant to be changed

Author: findepi

datafusion/functions/src/datetime/to_timestamp.rs

@@ -19,12 +19,14 @@ use std::any::Any;
 use std::sync::Arc;
 
 use crate::datetime::common::*;
+use arrow::array::Float64Array;
 use arrow::datatypes::DataType::*;
 use arrow::datatypes::TimeUnit::{Microsecond, Millisecond, Nanosecond, Second};
 use arrow::datatypes::{
     ArrowTimestampType, DataType, TimeUnit, TimestampMicrosecondType,
     TimestampMillisecondType, TimestampNanosecondType, TimestampSecondType,
 };
+use datafusion_common::format::DEFAULT_CAST_OPTIONS;
 use datafusion_common::{exec_err, Result, ScalarType, ScalarValue};
 use datafusion_expr::{
     ColumnarValue, Documentation, ScalarUDFImpl, Signature, Volatility,
@@ -319,9 +321,20 @@ impl ScalarUDFImpl for ToTimestampFunc {
             Int32 | Int64 => args[0]
                 .cast_to(&Timestamp(Second, None), None)?
                 .cast_to(&Timestamp(Nanosecond, None), None),
-            Null | Float64 | Timestamp(_, None) => {
+            Null | Timestamp(_, None) => {
                 args[0].cast_to(&Timestamp(Nanosecond, None), None)
             }
+            Float64 => {
+                let rescaled = arrow::compute::kernels::numeric::mul(
+                    &args[0].to_array(1)?,
+                    &arrow::array::Scalar::new(Float64Array::from(vec![1_000_000_000f64])),
+                )?;
+                Ok(ColumnarValue::Array(arrow::compute::cast_with_options(
+                    &rescaled,
+                    &Timestamp(Nanosecond, None),
+                    &DEFAULT_CAST_OPTIONS,
+                )?))
+            }
             Timestamp(_, Some(tz)) => {
                 args[0].cast_to(&Timestamp(Nanosecond, Some(tz)), None)
             }

datafusion/sqllogictest/test_files/timestamps.slt

@@ -503,12 +503,12 @@ SELECT COUNT(*) FROM ts_data_secs where ts > to_timestamp_seconds('2020-09-08 12
 query PPP
 SELECT to_timestamp(1.1) as c1, cast(1.1 as timestamp) as c2, 1.1::timestamp as c3;
 ----
-1970-01-01T00:00:00.000000001 1970-01-01T00:00:00.000000001 1970-01-01T00:00:00.000000001
+1970-01-01T00:00:01.100 1970-01-01T00:00:00.000000001 1970-01-01T00:00:00.000000001
 
 query PPP
 SELECT to_timestamp(-1.1) as c1, cast(-1.1 as timestamp) as c2, (-1.1)::timestamp as c3;
 ----
-1969-12-31T23:59:59.999999999 1969-12-31T23:59:59.999999999 1969-12-31T23:59:59.999999999
+1969-12-31T23:59:58.900 1969-12-31T23:59:59.999999999 1969-12-31T23:59:59.999999999
 
 query PPP
 SELECT to_timestamp(0.0) as c1, cast(0.0 as timestamp) as c2, 0.0::timestamp as c3;
@@ -518,12 +518,12 @@ SELECT to_timestamp(0.0) as c1, cast(0.0 as timestamp) as c2, 0.0::timestamp as
 query PPP
 SELECT to_timestamp(1.23456789) as c1, cast(1.23456789 as timestamp) as c2, 1.23456789::timestamp as c3;
 ----
-1970-01-01T00:00:00.000000001 1970-01-01T00:00:00.000000001 1970-01-01T00:00:00.000000001
+1970-01-01T00:00:01.234567890 1970-01-01T00:00:00.000000001 1970-01-01T00:00:00.000000001
 
 query PPP
 SELECT to_timestamp(123456789.123456789) as c1, cast(123456789.123456789 as timestamp) as c2, 123456789.123456789::timestamp as c3;
 ----
-1970-01-01T00:00:00.123456789 1970-01-01T00:00:00.123456789 1970-01-01T00:00:00.123456789
+1973-11-29T21:33:09.123456784 1970-01-01T00:00:00.123456789 1970-01-01T00:00:00.123456789
 
 # to_timestamp Decimal128 inputs