Add internal SEARCH operator and Sarg literal, replacing use of IN in RexCall.
Recently we started to allow IN in RexCalls to represent lists of constant values; previously it had only been allowed in SqlCall. The use is confusing, because a RexSubQuery is a sub-class of RexCall that may also use IN as its operator.
More important, we would like to be able to represent more general search arguments in a single RexCall. Examples:
- x BETWEEN 3 AND 10
- x > 3 AND x <= 10
- x NOT BETWEEN 3 AND 10
- x IS NULL OR x BETWEEN 3 AND 100 AND x != 50 OR x IN (200, 300, 400)
- x > 5 AND x < 10 AND x IN (3, 8, 10, 20)
All of these can be converted to sets of ranges, where each range has a lower or upper bound (or both), bounds can be open or closed, plus a flag to say whether NULL is an allowed value. Guava's RangeSet is an efficient implementation of range sets.
This change would create a new class Sarg to represent a range set as a literal. The new internal SEARCH operator tests whether an operand belongs to the range set.
A RexCall to SEARCH is converted back to SQL, typically an IN or OR.
This change would obsolete the use of IN in RexCall to represent a fixed list of values. (This is a breaking change, but when we first allowed IN in RexCall, in
CALCITE-2444, it was only intended to be for RelToSqlConverter. Most people still believe that IN is not allowed.)