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https://issues.apache.org/jira/browse/PARQUET-861?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16410497#comment-16410497
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ASF GitHub Bot commented on PARQUET-861:
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lekv closed pull request #49: PARQUET-861: Document INT96 timestamps
URL: https://github.com/apache/parquet-format/pull/49
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diff --git a/LogicalTypes.md b/LogicalTypes.md
index c411dbfa..717b2903 100644
--- a/LogicalTypes.md
+++ b/LogicalTypes.md
@@ -144,6 +144,18 @@ example, there is no requirement that a large number of
days should be
expressed as a mix of months and days because there is not a constant
conversion from days to months.
+### INT96 timestamps (also called IMPALA_TIMESTAMP)
+
+_(deprecated)_ Timestamps saved as an `int96` are made up of the nanoseconds
in the day
+(first 8 byte) and the Julian day (last 4 bytes). No timezone is attached to
this value.
+To convert the timestamp into nanoseconds since the Unix epoch, 00:00:00.000000
+on 1 January 1970, the following formula can be used:
+`(julian_day - 2440588) * (86400 * 1000 * 1000 * 1000) + nanoseconds`.
+The magic number `2440588` is the julian day for 1 January 1970.
+
+Note that these timestamps are the common usage of the `int96` physical type
and are not
+marked with a special logical type annotation.
+
## Embedded Types
### JSON
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> Document INT96 timestamps
> -------------------------
>
> Key: PARQUET-861
> URL: https://issues.apache.org/jira/browse/PARQUET-861
> Project: Parquet
> Issue Type: Improvement
> Components: parquet-format
> Reporter: Uwe L. Korn
> Assignee: Uwe L. Korn
> Priority: Major
>
> Although considered as deprecated, they should be documented as the format is
> quite special.
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