beliefer commented on code in PR #35041:
URL: https://github.com/apache/spark/pull/35041#discussion_r851111216
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/percentiles.scala:
##########
@@ -317,6 +274,78 @@ case class Percentile(
bis.close()
}
}
+}
+
+/**
+ * The Percentile aggregate function returns the exact percentile(s) of
numeric column `expr` at
+ * the given percentage(s) with value range in [0.0, 1.0].
+ *
+ * Because the number of elements and their partial order cannot be determined
in advance.
+ * Therefore we have to store all the elements in memory, and so notice that
too many elements can
+ * cause GC paused and eventually OutOfMemory Errors.
+ *
+ * @param child child expression that produce numeric column value with
`child.eval(inputRow)`
+ * @param percentageExpression Expression that represents a single percentage
value or an array of
+ * percentage values. Each percentage value must
be in the range
+ * [0.0, 1.0].
+ */
+// scalastyle:off line.size.limit
+@ExpressionDescription(
+ usage =
+ """
+ _FUNC_(col, percentage [, frequency]) - Returns the exact percentile
value of numeric
+ or ansi interval column `col` at the given percentage. The value of
percentage must be
+ between 0.0 and 1.0. The value of frequency should be positive integral
+
+ _FUNC_(col, array(percentage1 [, percentage2]...) [, frequency]) -
Returns the exact
+ percentile value array of numeric column `col` at the given
percentage(s). Each value
+ of the percentage array must be between 0.0 and 1.0. The value of
frequency should be
+ positive integral
+
+ """,
+ examples = """
+ Examples:
+ > SELECT _FUNC_(col, 0.3) FROM VALUES (0), (10) AS tab(col);
+ 3.0
+ > SELECT _FUNC_(col, array(0.25, 0.75)) FROM VALUES (0), (10) AS
tab(col);
+ [2.5,7.5]
+ > SELECT _FUNC_(col, 0.5) FROM VALUES (INTERVAL '0' MONTH), (INTERVAL
'10' MONTH) AS tab(col);
+ 5.0
+ > SELECT _FUNC_(col, array(0.2, 0.5)) FROM VALUES (INTERVAL '0' SECOND),
(INTERVAL '10' SECOND) AS tab(col);
+ [2000000.0,5000000.0]
+ """,
+ group = "agg_funcs",
+ since = "2.1.0")
+// scalastyle:on line.size.limit
+case class Percentile(
+ child: Expression,
+ percentageExpression: Expression,
+ frequencyExpression : Expression,
+ mutableAggBufferOffset: Int = 0,
+ inputAggBufferOffset: Int = 0,
+ reverse: Boolean = false) extends PercentileBase {
Review Comment:
order by col with desc
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