Hi colleagues,
I am trying to implement case insensitive resolution of column/table/schema
names for our Apache Calcite integration in Hazelcast and got stuck. I hope
that the community might help me.
Consider that we have a table source that contains the following Java class:
class Employee {
LocalDate birthDate
}
I would like to have an SQL engine that could resolve identifiers in
accordance with ANSI SQL standard, which basically says that unquoted
identifiers should be compared in a case-insensitive way, while quoted
identifiers should be compared in a case-sensitive way. Let's focus on
columns only for now:
SELECT birthDate FROM employee // OK
SELECT birthdate FROM employee // OK
SELECT BIRTHDATE FROM employee // OK
SELECT `birthDate` FROM employee // OK
SELECT `birthdate` FROM employee // Fail
SELECT `BIRTHDATE` FROM employee // Fail
That is, my source is a collection of Java objects, and the natural name of
the column is "birthDate". But I would like it to be accessible as
"birthDate", birthDate, BIRTHDate, etc.
My problem comes from the fact that casing configuration is applied during
parsing and by the time the table is asked for a column, the information
whether the user request was quoted or not is lost. Consider that I have a
table RelDataType["birthDate"]. Now consider what happens with different
combinations of casing configuration:
1) [unquoted=UNCHANGED, quoted=UNCHANGED]: "SELECT BIRTHDATE" doesn't work
obviously
2) [unquoted=UPPER, quoted=UNCHANGED]: "SELECT BIRTHDATE" doesn't work
again, because parser normalizes unqouted identifier to upper case, but
RelDataType has a column "birthDate"
3) Same as p.2, but with manual normalization of RelDataType
to RelDataType["BIRTHDATE"]: "SELECT BIRTHDATE" works now, but "SELECT
`birthDate`" don't!
Is there any built-in solution to the above problem?
Regards,
Vladimir.
