Fix to reorg when using Db2

Author: KodaiD

core/src/main/java/com/scalar/db/storage/jdbc/JdbcAdmin.java

@@ -868,13 +868,11 @@ public void dropColumnFromTable(String namespace, String table, String columnNam
       TableMetadata currentTableMetadata = getTableMetadata(namespace, table);
       TableMetadata updatedTableMetadata =
           TableMetadata.newBuilder(currentTableMetadata).removeColumn(columnName).build();
-      String dropColumnStatement =
-          "ALTER TABLE "
-              + encloseFullTableName(namespace, table)
-              + " DROP COLUMN "
-              + enclose(columnName);
+      String[] dropColumnStatements = rdbEngine.dropColumnSql(namespace, table, columnName);
       try (Connection connection = dataSource.getConnection()) {
-        execute(connection, dropColumnStatement);
+        for (String dropColumnStatement : dropColumnStatements) {
+          execute(connection, dropColumnStatement);
+        }
         addTableMetadata(connection, namespace, table, updatedTableMetadata, false, true);
       }
     } catch (SQLException e) {

core/src/main/java/com/scalar/db/storage/jdbc/RdbEngineDb2.java

@@ -246,6 +246,17 @@ public void dropNamespaceTranslateSQLException(SQLException e, String namespace)
     throw new ExecutionException("Dropping the schema failed: " + namespace, e);
   }
 
+  @Override
+  public String[] dropColumnSql(String namespace, String table, String columnName) {
+    return new String[] {
+      "ALTER TABLE "
+          + encloseFullTableName(namespace, table)
+          + " DROP COLUMN "
+          + enclose(columnName),
+      "CALL SYSPROC.ADMIN_CMD('REORG TABLE " + encloseFullTableName(namespace, table) + "')"
+    };
+  }
+
   @Override
   public String alterColumnTypeSql(
       String namespace, String table, String columnName, String columnType) {

core/src/main/java/com/scalar/db/storage/jdbc/RdbEngineStrategy.java

@@ -98,6 +98,15 @@ default String truncateTableSql(String namespace, String table) {
   void dropNamespaceTranslateSQLException(SQLException e, String namespace)
       throws ExecutionException;
 
+  default String[] dropColumnSql(String namespace, String table, String columnName) {
+    return new String[] {
+      "ALTER TABLE "
+          + encloseFullTableName(namespace, table)
+          + " DROP COLUMN "
+          + enclose(columnName)
+    };
+  }
+
   String alterColumnTypeSql(String namespace, String table, String columnName, String columnType);
 
   String tableExistsInternalTableCheckSql(String fullTableName);