bkietz commented on a change in pull request #11080:
URL: https://github.com/apache/arrow/pull/11080#discussion_r714193210
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File path: cpp/src/arrow/compute/kernels/codegen_internal.cc
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@@ -155,24 +161,44 @@ std::shared_ptr<DataType> CommonNumeric(const ValueDescr*
begin, size_t count) {
std::shared_ptr<DataType> CommonTimestamp(const std::vector<ValueDescr>&
descrs) {
TimeUnit::type finest_unit = TimeUnit::SECOND;
+ const std::string* timezone = nullptr;
+ bool saw_date32 = false;
+ bool saw_date64 = false;
for (const auto& descr : descrs) {
auto id = descr.type->id();
// a common timestamp is only possible if all types are timestamp like
switch (id) {
case Type::DATE32:
+ // Date32's unit is days, but the coarsest we have is seconds
+ saw_date32 = true;
+ continue;
case Type::DATE64:
+ finest_unit = std::max(finest_unit, TimeUnit::MILLI);
+ saw_date64 = true;
continue;
- case Type::TIMESTAMP:
- finest_unit =
- std::max(finest_unit, checked_cast<const
TimestampType&>(*descr.type).unit());
+ case Type::TIMESTAMP: {
+ const auto& ty = checked_cast<const TimestampType&>(*descr.type);
+ // Don't cast to common timezone by default (may not make
+ // sense for all kernels)
+ if (timezone && *timezone != ty.timezone()) return nullptr;
+ timezone = &ty.timezone();
+ finest_unit = std::max(finest_unit, ty.unit());
continue;
+ }
default:
return nullptr;
}
}
- return timestamp(finest_unit);
+ if (timezone) {
+ // At least one timestamp seen
+ return timestamp(finest_unit, *timezone);
+ } else if (saw_date32 && saw_date64) {
+ // Saw mixed date types
+ return date64();
+ }
+ return nullptr;
Review comment:
nullptr is returned to indicate that no common temporal type was found;
returning date32 here would mean `CommonTemporal(float64(), utf8()) ===
date32()`
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