Github user jinfengni commented on the issue:
https://github.com/apache/drill/pull/819
My understanding is Drill would hit a schema change between column with
type of varchar(5) and varchar(10). However, the length calculated in this PR
is from the query metadeta (function parameter, string literal), which will not
change across different batches. In that sense, we should not see schema change
exception, just because of varchar length.
The following code shows that varchar(5) is different from varchar(10),
also different from varchar without setting length.
```java
TypeProtos.MajorType varchar5 = TypeProtos.MajorType.newBuilder()
.setMinorType(TypeProtos.MinorType.VARCHAR)
.setMode(TypeProtos.DataMode.OPTIONAL)
.setPrecision(5)
.build();
TypeProtos.MajorType varchar10 = TypeProtos.MajorType.newBuilder()
.setMinorType(TypeProtos.MinorType.VARCHAR)
.setMode(TypeProtos.DataMode.OPTIONAL)
.setPrecision(10)
.build();
TypeProtos.MajorType varcharNoLength = TypeProtos.MajorType.newBuilder()
.setMinorType(TypeProtos.MinorType.VARCHAR)
.setMode(TypeProtos.DataMode.OPTIONAL)
.build();
System.out.println(varchar5.equals(varchar10) ? "varchar5 equals
varchr10" : "varchar5 NOT equals varchr10" );
System.out.println(varchar5.equals(varcharNoLength) ? "varchar5 equals
varchrNoLength" : "varchar5 NOT equals varchrNoLength" );
```
output:
```
varchar5 NOT equals varchr10
varchar5 NOT equals varchrNoLength
```
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