Using Calcite to parse an SQL interval day seems to always result in a
RexLiteral with a scale of 6, but with the value a millisecond representation
of the interval. This is because SqlLiteral.getValueAs() always returns
milliseconds, and the default fractional second precision is 6. The resulting
RexLiteral scale confused me since the value of 6 suggested a microsecond
representation.
I tried to change this behaviour in several ways:
1.
Change the default fractional second interval precision to 3.
2.
Change SqlNodeToRexConverterImpl.convertLiteral() to scale the value passed to
RexBuilder.makeIntervalLiteral() to microseconds in order to match the target
scale returned by
sqlIntervalQualifier.getFractionalSecondPrecision(rexBuilder.getTypeFactory().getTypeSystem()).
3.
Change SqlNodeToRexConverterImpl.convertLiteral() so that it creates a new
SqlIntervalQualifier that matches the one associated with the SqlLiteral but
with a fractional second precision of 3 to indicate milliseconds. This has no
effect because RexBuilder.makeIntervalLiteral() creates the RexLiteral's
RelDataType by passing the interval qualifier to
SqlTypeFactoryImpl.createSqlIntervalType(), and the canonize() call that
happens there discards the fractional second precision — I guess by using an
interned value with default fractional second precision.
While some of these approaches did produce a RexLiteral that looked more as I
expected, they all broke many Calcite tests.
Is it expected that day/time intervals should always be represented in
milliseconds but also report a scale of 6? If not, can you suggest the right
approach to implement the correct behaviour?
Thanks in advance for your help,
Mark.
