// execute query based on what kind of scan is needed
// if no where clause, scan the entire table
CandidateIndexImpl index = where==null?
CandidateIndexImpl.getIndexForNullWhereClause():
where.getBestCandidateIndex(context);
ScanType scanType = index.getScanType();
Map<String, Object> explain = newExplain(index, scanType);
context.setExplain(explain);
ResultData result = null;
Index storeIndex;