private boolean isValidField(ExprNodeFieldDesc field) {
    return fieldValidator == null || fieldValidator.validate(field);
  }
Analyzes a predicate.

@param predicate predicate to be analyzed

@param searchConditions receives conditions produced by analysis

@return residual predicate which could not be translated to
searchConditions
ql/src/java/org/apache/hadoop/hive/ql/index/IndexPredicateAnalyzer.java