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https://issues.apache.org/jira/browse/HIVE-24693?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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David Mollitor reassigned HIVE-24693:
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> 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
>
> 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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