beliefer commented on a change in pull request #27428:
URL: https://github.com/apache/spark/pull/27428#discussion_r451948803
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/RewriteDistinctAggregates.scala
##########
@@ -118,7 +118,75 @@ import org.apache.spark.sql.types.IntegerType
* LocalTableScan [...]
* }}}
*
- * The rule does the following things here:
+ * Third example: single distinct aggregate function with filter clauses (in
sql):
+ * {{{
+ * SELECT
+ * COUNT(DISTINCT cat1) FILTER (WHERE id > 1) as cat1_cnt,
+ * COUNT(DISTINCT cat2) as cat2_cnt,
+ * SUM(value) AS total
+ * FROM
+ * data
+ * GROUP BY
+ * key
+ * }}}
+ *
+ * This translates to the following (pseudo) logical plan:
+ * {{{
+ * Aggregate(
+ * key = ['key]
+ * functions = [COUNT(DISTINCT 'cat1) with FILTER('id > 1),
+ * COUNT(DISTINCT 'cat2),
+ * sum('value)]
+ * output = ['key, 'cat1_cnt, 'cat2_cnt, 'total])
+ * LocalTableScan [...]
+ * }}}
+ *
+ * This rule rewrites this logical plan to the following (pseudo) logical plan:
+ * {{{
+ * Aggregate(
+ * key = ['key]
+ * functions = [count(if (('gid = 1)) '_gen_distinct_1 else null),
+ * count(if (('gid = 2)) '_gen_distinct_2 else null),
+ * first(if (('gid = 0)) 'total else null) ignore nulls]
+ * output = ['key, 'cat1_cnt, 'cat2_cnt, 'total])
+ * Aggregate(
+ * key = ['key, '_gen_distinct_1, '_gen_distinct_2, 'gid]
+ * functions = [sum('value)]
+ * output = ['key, '_gen_distinct_1, '_gen_distinct_2, 'gid, 'total])
+ * Expand(
+ * projections = [('key, null, null, 0, cast('value as bigint)),
+ * ('key, if ('id > 1) 'cat1 else null, null, 1, null),
+ * ('key, null, 'cat2, 2, null)]
+ * output = ['key, '_gen_distinct_1, '_gen_distinct_2, 'gid, 'value])
Review comment:
For example:
`SELECT b, COUNT(DISTINCT cat1), COUNT(DISTINCT cat1) FILTER (WHERE id > 0)
FROM cachedData GROUP BY b`
we can't keep the name `cat1`, `cat1`
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org
For additional commands, e-mail: reviews-h...@spark.apache.org
