[CALCITE-3973] Hints should not unparse as enclosed in parentheses

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.22.0
• Fix Version/s: 1.23.0
• Assignee: Unassigned
• Reporter: Alex Baden
• Created: 06/May/20 00:19
• Updated: 24/May/20 12:00
• Resolved: 07/May/20 05:50

Description

When using the new SQL hints feature:

 

select /*+ cpu */ x from test limit 2;

If one calls to SqlString() on the node:

 

 

node.toSqlString(CalciteSqlDialect.DEFAULT).toString()

 

We get:

 

'SELECT /*+ ("cpu") */ "x" FROM "test" FETCH NEXT 2 ROWS ONLY'

which is not valid SQL for a hint. It looks like the precedence options need to be modified when writing out the hint in SqlSelectOperator.unparse

 

We do some rewriting of the sql statement and then re-parse it, so this is preventing us from using hints. I am happy to submit a patch if I am headed in the right direction with the description above.