ccaominh commented on a change in pull request #9488: Match GREATEST/LEAST
function behavior to other DBs
URL: https://github.com/apache/druid/pull/9488#discussion_r390015518
##########
File path: docs/querying/sql.md
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@@ -334,6 +332,22 @@ simplest way to write literal timestamps in other time
zones is to use TIME_PARS
|<code>timestamp_expr { + | - } <interval_expr><code>|Add or subtract an
amount of time from a timestamp. interval_expr can include interval literals
like `INTERVAL '2' HOUR`, and may include interval arithmetic as well. This
operator treats days as uniformly 86400 seconds long, and does not take into
account daylight savings time. To account for daylight savings time, use
TIME_SHIFT instead.|
+### Reduction functions
+
+Reduction functions operate on zero or more expressions and return a single
expression. If no expressions are passed
+as arguments, then the result is `NULL`. The expressions must all be
convertible to a
+common data type, which will be the type of the result:
+* If any argument is `NULL`, the result is `NULL`.
+* If the arguments comprise a mix of numbers and strings, the arguments are
interpreted as strings.
Review comment:
I'm not sure what other reduction functions we'll want to add in the future,
but ideally the behavior is consistent. That being said, I wouldn't be
surprised if the docs need to be reorganized to accommodate future reduction
functions.
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