Hequn Cheng created FLINK-8782:
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Summary: Rmove count agg if it is generated for sum agg in over
window
Key: FLINK-8782
URL: https://issues.apache.org/jira/browse/FLINK-8782
Project: Flink
Issue Type: Improvement
Components: Table API & SQL
Reporter: Hequn Cheng
Currently, sum agg in over window will generate another count agg which is
redundant and affect performance.
For the following sql:
{code:java}
val sqlQuery = "SELECT a, " +
" SUM(b) OVER (" +
" PARTITION BY a ORDER BY proctime ROWS BETWEEN 3 PRECEDING AND CURRENT ROW) "
+
"FROM MyTable"{code}
the corresponding {{LogicalProject}} generated by over is:
{code:java}
CASE(>(COUNT($1) OVER (PARTITION BY $0 ORDER BY $5 ROWS BETWEEN 3 PRECEDING AND
CURRENT ROW), 0), CAST($SUM0($1) OVER (PARTITION BY $0 ORDER BY $5 ROWS BETWEEN
3 PRECEDING AND CURRENT ROW)):BIGINT, null){code}
count is used to return null if count is zero while this logic is redundant
since sum agg function will return null in this case.
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