From 99b9661d0aa9139a1e1fc025c8a6542b69dd2ca9 Mon Sep 17 00:00:00 2001
From: Clearvive <143773256+Clearvive@users.noreply.github.com>
Date: Thu, 25 Jan 2024 16:56:03 +0800
Subject: [PATCH] [#1701] fix(mysql): Compatible with lower versions of MySQL
 driver, unable to obtain table comments. (#1702)

### What changes were proposed in this pull request?
Compatible with lower versions of MySQL driver, unable to obtain table
comments.


### Why are the changes needed?
Fix: #1701

### Does this PR introduce _any_ user-facing change?
NO

### How was this patch tested?
UT/IT

---------

Co-authored-by: Clearvive <clearvive@datastrato.com>
---
 .../mysql/operation/MysqlTableOperations.java  | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/catalogs/catalog-jdbc-mysql/src/main/java/com/datastrato/gravitino/catalog/mysql/operation/MysqlTableOperations.java b/catalogs/catalog-jdbc-mysql/src/main/java/com/datastrato/gravitino/catalog/mysql/operation/MysqlTableOperations.java
index bae9f3744cb..e1fcd293cf0 100644
--- a/catalogs/catalog-jdbc-mysql/src/main/java/com/datastrato/gravitino/catalog/mysql/operation/MysqlTableOperations.java
+++ b/catalogs/catalog-jdbc-mysql/src/main/java/com/datastrato/gravitino/catalog/mysql/operation/MysqlTableOperations.java
@@ -18,6 +18,7 @@
 import com.datastrato.gravitino.rel.expressions.transforms.Transform;
 import java.sql.Connection;
 import java.sql.DatabaseMetaData;
+import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Statement;
@@ -49,6 +50,11 @@ public JdbcTable load(String databaseName, String tableName) throws NoSuchTableE
             String.format("Table %s does not exist in %s.", tableName, databaseName));
       }
       String comment = table.getString("REMARKS");
+      if (StringUtils.isEmpty(comment)) {
+        // In Mysql version 5.7, the comment field value cannot be obtained in the driver API.
+        LOG.warn("Not found comment in mysql driver api. Will try to get comment from sql");
+        comment = loadCommentFromSql(connection, tableName);
+      }
 
       // 2.Get column information
       ResultSet columns = metaData.getColumns(databaseName, null, tableName, null);
@@ -84,6 +90,18 @@ public JdbcTable load(String databaseName, String tableName) throws NoSuchTableE
     }
   }
 
+  private String loadCommentFromSql(Connection connection, String tableName) throws SQLException {
+    try (PreparedStatement statement = connection.prepareStatement("SHOW TABLE STATUS LIKE ?")) {
+      statement.setString(1, tableName);
+      try (ResultSet resultSet = statement.executeQuery()) {
+        if (!resultSet.next()) {
+          return null;
+        }
+        return resultSet.getString("COMMENT");
+      }
+    }
+  }
+
   @Override
   public List<String> listTables(String databaseName) throws NoSuchSchemaException {
     try (Connection connection = getConnection(databaseName)) {