[IMPALA-8103] Plan hints show up as "--" comments in analysed query

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: Impala 3.2.0
• Component/s: Frontend
• Target Version: Product Backlog
• Epic Color: ghx-label-9
• Assignee: Andrew Sherman
• Reporter: Tim Armstrong
• Created: 23/Jan/19 21:09
• Updated: 06/Feb/19 17:17
• Resolved: 06/Feb/19 17:17

Description

I noticed that the hints added in IMPALA-5821 show up in the – style rather than /**/

    Sql Statement: select * from tpch.lineitem join /*+ broadcast */ tpch.part on l_partkey = p_partkey limit 
...
Analyzed query: SELECT * FROM tpch.lineitem INNER JOIN
-- +broadcast
tpch.part ON l_partkey = p_partkey LIMIT CAST(5 AS TINYINT)

I guess this works and maybe its fine, but I was really confused when I saw it. It looks like getPlanHintsSql() uses this to generate views in such a way that Hive will ignore the hints, but that concern doesn't seem relevant to this use case.