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https://issues.apache.org/jira/browse/HIVE-24693?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17275222#comment-17275222
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David Mollitor commented on HIVE-24693:
---------------------------------------
Hitting a weird issue. There's a unit test that goes from Date to Timestamp
that is failing. It seems that the Timestamp value and the toString do not
agree with each other:
{code:java}
public static void main(String[] args) throws IOException, URISyntaxException
{
DateTimeFormatterBuilder builder = new DateTimeFormatterBuilder();
// Date and time parts
builder.append(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
// Fractional part
builder.optionalStart().appendFraction(ChronoField.NANO_OF_SECOND, 0, 9,
true).optionalEnd();
DateTimeFormatter PRINT_FORMATTER = builder.toFormatter();
int daysSinceEpoch = -1133938638;
LocalDate localDate = LocalDate.ofEpochDay(daysSinceEpoch);
long epochMillis =
localDate.atStartOfDay().toInstant(ZoneOffset.UTC).toEpochMilli();
LocalDateTime localDateTime =
LocalDateTime.ofInstant(Instant.ofEpochMilli(epochMillis), ZoneOffset.UTC);
System.out.println(epochMillis);
System.out.println(localDate);
System.out.println(localDateTime.format(PRINT_FORMATTER));
}
{code}
It's a big negative number. It should be a negative date, however,:
{code:none}
-97972298323200000
-3102649-06-17
+3102650-06-17 00:00:00
{code}
For some reason, the print formatted date is different that the toString value.
Hmmm.
> Parquet Timestamp Values Read/Write Very Slow
> ---------------------------------------------
>
> Key: HIVE-24693
> URL: https://issues.apache.org/jira/browse/HIVE-24693
> Project: Hive
> Issue Type: Improvement
> Reporter: David Mollitor
> Assignee: David Mollitor
> Priority: Critical
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Parquet {{DataWriteableWriter}} relias on {{NanoTimeUtils}} to convert a
> timestamp object into a binary value. The way in which it does this,... it
> calls {{toString()}} on the timestamp object, and then parses the String.
> This particular timestamp do not carry a timezone, so the string is something
> like:
> {{2021-21-03 12:32:23.0000...}}
> The parse code tries to parse the string assuming there is a time zone, and
> if not, falls-back and applies the provided "default time zone". As was
> noted in [HIVE-24353], if something fails to parse, it is very expensive to
> try to parse again. So, for each timestamp in the Parquet file, it:
> * Builds a string from the time stamp
> * Parses it (throws an exception, parses again)
> There is no need to do this kind of string manipulations/parsing, it should
> just be using the epoch millis/seconds/time stored internal to the Timestamp
> object.
> {code:java}
> // Converts Timestamp to TimestampTZ.
> public static TimestampTZ convert(Timestamp ts, ZoneId defaultTimeZone) {
> return parse(ts.toString(), defaultTimeZone);
> }
> {code}
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