Ted-Jiang commented on a change in pull request #1991:
URL: https://github.com/apache/arrow-datafusion/pull/1991#discussion_r825776860
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File path: docs/source/user-guide/sql/datafusion-functions.md
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@@ -84,3 +84,31 @@ Note that `CAST(.. AS Timestamp)` converts to Timestamps
with Nanosecond resolut
- Other Timestamp() columns or values
Note that `CAST(.. AS Timestamp)` converts to Timestamps with Nanosecond
resolution; this function is the only way to convert/cast to seconds resolution.
+
+## `EXTRACT, date_part`
+
+`EXTRACT(field FROM source)`
+
+- The extract function retrieves subfields such as year or hour from date/time
values.
+ source must be a value expression of type timestamp, Data32, Data64 field is
an identifier that selects what field to extract from the source value.
+ The extract function returns values of type u32.
Review comment:
@liukun4515 We need a discussion about wether need support negative
`timestamp `or `date`
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