Hi, I want to re-use column alias in the select clause to avoid sub query.
For example: select check(key) as b, abs(b) as abs, value1, value2, ..., value30 from test The query above does not work, because b is not defined in the test's schema. In stead, I should change the query to the following: select check(key) as b, abs(check(key)) as abs, value1, value2, ..., value30 from test Apparently, check function are called twice. In my use case, the check function is time-consuming. The workaround is to use sub-query : select b, abs(b), value1, value2, ..., value30 as abs from ( select check(key) as b, value1, value2, ..., value30 from test ) t The problem is that I have to repeat the 30 following column twice. Image the following case which does not work： select check(key) as b, abs(b) as absv, tan(absv) as tanv, value1, value2, ..., value30 from test In order not to call my check function many times, I need to change the query to 3 sub-queries, which makes query too long, hard to read. I am wondering whether we can reuse column alias in an efficient way ? Thank you -- View this message in context: http://apache-spark-user-list.1001560.n3.nabble.com/SPARK-SQL-Re-use-col-alias-in-the-select-clause-to-avoid-sub-query-tp23645.html Sent from the Apache Spark User List mailing list archive at Nabble.com. --------------------------------------------------------------------- To unsubscribe, e-mail: user-unsubscr...@spark.apache.org For additional commands, e-mail: user-h...@spark.apache.org
