mateczagany commented on code in PR #29080:
URL: https://github.com/apache/flink/pull/29080#discussion_r3924552433
##########
flink-table/flink-table-runtime/src/main/java/org/apache/flink/table/runtime/functions/VariantCastUtils.java:
##########
@@ -180,12 +189,14 @@ private static String decimalTarget(int precision, int
scale) {
}
/**
- * Reads a timestamp variant as the target {@code TIMESTAMP}. A variant
keeps microseconds, so
- * fractional seconds beyond the target precision are truncated, the same
as a regular {@code
- * TIMESTAMP} to {@code TIMESTAMP(p)} cast.
+ * Reads a timestamp variant as the target {@code TIMESTAMP}. {@link
Variant#getDateTime()}
+ * already accepts both the microsecond ({@link Variant.Type#TIMESTAMP})
and nanosecond ({@link
+ * Variant.Type#TIMESTAMP_NS}) encodings. Fractional seconds beyond the
target precision are
+ * truncated, the same as a regular {@code TIMESTAMP} to {@code
TIMESTAMP(p)} cast.
*/
public static TimestampData toTimestamp(Variant variant, int precision) {
- if (variant.getType() != Variant.Type.TIMESTAMP) {
+ final Variant.Type type = variant.getType();
+ if (type != Variant.Type.TIMESTAMP && type !=
Variant.Type.TIMESTAMP_NS) {
throw unsupportedKind(variant, String.format("TIMESTAMP(%d)",
precision));
}
return DateTimeUtils.truncate(
Review Comment:
There seems to be a pre-existing bug here, as `DateTimeUtils.truncate` uses
`Integer.toString(ts.toLocalDateTime().getNano())` to check the input's
precision, which will drop the leading zeros.
This results in casting a `TIMESTAMP_NS` value with fraction .000123456 to
`TIMESTAMP(6)` keeping all its nine digits, as `Integer.toString()` will return
a string with a length of 6.
The following test would fail:
```
CastTestSpecBuilder.testCastTo(TIMESTAMP(6))
.fromCase(
VARIANT(),
Variant.newBuilder().of(LocalDateTime.of(2020, 1, 1, 12,
0, 0, 123_456)),
TimestampData.fromLocalDateTime(LocalDateTime.of(2020, 1,
1, 12, 0, 0, 123_000)))
```
with:
```
Expected :2020-01-01T12:00:00.000123
Actual :2020-01-01T12:00:00.000123456
```
Could you please fix the helper and include this test?
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