fix: Tuple::serialize_to & Tuple::deserialize_from for `LogicalTy…

…pe::Char`

src/execution/volcano/dql/describe.rs

@@ -59,7 +59,7 @@ impl Describe {
                     datatype
                         .raw_len()
                         .map(|len| len.to_string())
-                        .unwrap_or_default(),
+                        .unwrap_or_else(|| "DYNAMIC".to_string()),
                 ))),
                 Arc::new(DataValue::Utf8(Some(column.nullable.to_string()))),
                 key_fn(column),

src/types/tuple.rs

@@ -115,10 +115,15 @@ impl Tuple {
             } else {
                 let mut value_bytes = value.to_raw();
 
-                if types[i].raw_len().is_none() {
+                if let Some(len) = types[i].raw_len() {
+                    let difference = len.saturating_sub(value_bytes.len());
+
+                    bytes.append(&mut value_bytes);
+                    bytes.append(&mut vec![0; difference]);
+                } else {
                     bytes.append(&mut (value_bytes.len() as u32).encode_fixed_vec());
+                    bytes.append(&mut value_bytes);
                 }
-                bytes.append(&mut value_bytes);
             }
         }
 

src/types/value.rs

@@ -440,7 +440,18 @@ impl DataValue {
                 buf.copy_from_slice(bytes);
                 f64::from_ne_bytes(buf)
             })),
-            LogicalType::Char(_) | LogicalType::Varchar(_) => DataValue::Utf8(
+            LogicalType::Char(_) => {
+                // https://dev.mysql.com/doc/refman/8.0/en/char.html#:~:text=If%20a%20given%20value%20is%20stored%20into%20the%20CHAR(4)%20and%20VARCHAR(4)%20columns%2C%20the%20values%20retrieved%20from%20the%20columns%20are%20not%20always%20the%20same%20because%20trailing%20spaces%20are%20removed%20from%20CHAR%20columns%20upon%20retrieval.%20The%20following%20example%20illustrates%20this%20difference%3A
+                let value = (!bytes.is_empty()).then(|| {
+                    let last_non_zero_index = match bytes.iter().rposition(|&x| x != 0) {
+                        Some(index) => index + 1,
+                        None => 0,
+                    };
+                    String::from_utf8(bytes[0..last_non_zero_index].to_owned()).unwrap()
+                });
+                DataValue::Utf8(value)
+            }
+            LogicalType::Varchar(_) => DataValue::Utf8(
                 (!bytes.is_empty()).then(|| String::from_utf8(bytes.to_owned()).unwrap()),
             ),
             LogicalType::Date => {

tests/slt/describe.slt

@@ -4,9 +4,9 @@ create table t9 (c1 int primary key, c2 int default 0, c3 varchar unique);
 query TTTTI
 describe t9;
 ----
-c1 INTEGER false PRIMARY null
-c2 INTEGER true EMPTY 0
-c3 VARCHAR true UNIQUE null
+c1 INTEGER 4 false PRIMARY null
+c2 INTEGER 4 true EMPTY 0
+c3 VARCHAR DYNAMIC true UNIQUE null
 
 statement ok
 drop table t9;

tests/slt/insert.slt

@@ -44,6 +44,9 @@ select * from t
 7 10 1 null
 8 null null null
 
+statement ok
+drop table t;
+
 statement ok
 create table t1(id int primary key, v1 bigint default 233)
 
@@ -73,4 +76,28 @@ select * from t1
 2 233
 3 233
 4 0
-5 233
+5 233
+
+statement ok
+drop table t1;
+
+statement ok
+create table t2(id int primary key, v1 char(10), v2 varchar);
+
+statement ok
+insert into t2 (id, v1, v2) values (0, 'foo', 'foo');
+
+query ITT
+select * from t2;
+----
+0 foo foo
+
+query B
+select v1 = v2 from t2;
+----
+true
+
+statement ok
+drop table t2;
+
+

tests/slt/sql_2016/E021_10.slt

@@ -1,12 +1,12 @@
 # E021-10: Implicit casting among the fixed-length and variable-length character string types
 
-# TODO: CHARACTER and CHARACTER VARYING
+statement ok
+CREATE TABLE TABLE_E021_10_01_01 ( ID INT PRIMARY KEY, A CHARACTER ( 10 ) , B CHARACTER VARYING ( 15 ) );
 
-# statement ok
-# CREATE TABLE TABLE_E021_10_01_01 ( A CHARACTER ( 10 ) , B CHARACTER VARYING ( 15 ) );
+statement ok
+INSERT INTO TABLE_E021_10_01_01 ( ID, A, B ) VALUES ( 0, 'foo' , 'bar' );
 
-# statement ok
-# INSERT INTO TABLE_E021_10_01_01 ( A, B ) VALUES ( 'foo' , 'bar' );
-
-# query B
-# SELECT A = B FROM TABLE_E021_10_01_01
+query B
+SELECT A = B FROM TABLE_E021_10_01_01
+----
+false