Fix CSV scanner for handling filter predicate on a VARCHAR column

CSV scan does not care about delimiter in a CSV file, but query
processor should care the end of each column value, i.e., ‘\0’.

Because query parser parses each selection predicate by adding ‘\0’ at
the end of the predicate value, query processor cannot handle the query
correctly if we ignore the existence of delimiter in a raw tuple in CSV
file.

This simple solution fix the case by replacing delimiter to ‘\0’, and
thus StringCompare in type/type_util.h works correctly.

src/codegen/util/csv_scanner.cpp

@@ -362,6 +362,9 @@ void CSVScanner::ProduceCSV(char *line) {
     cols_[col_idx].len = static_cast<uint32_t>(col_end - col_begin);
     cols_[col_idx].is_null = (cols_[col_idx].len == 0);
 
+    // Yoon-Min: replace delimiter to '\0' to fix a bug while comparing
+    // filter condition in a query and column value of VARCHAR type
+    *iter = 0;
     // Eat delimiter, moving to next column
     iter++;
   }
@@ -372,4 +375,4 @@ void CSVScanner::ProduceCSV(char *line) {
 
 }  // namespace util
 }  // namespace codegen
-}  // namespace peloton
+}  // namespace peloton