String sql = "SELECT t1.id, count(1) as total_count FROM my_db1.table1 t1 LEFT JOIN my_db2.table2 t2 ON t1.id = t2.id GROUP BY t1.id";
AstParser astParser = new AstParser();
INode ast = (INode) astParser.parse(sql);

String sql = "SELECT t1.id, count(1) as total_count FROM my_db1.table1 t1 LEFT JOIN my_db2.table2 t2 ON t1.id = t2.id GROUP BY t1.id";
AstParser astParser = new AstParser();
INode ast = (INode) astParser.parse(sql);
ReferredTablesDetector referredTablesDetector = new ReferredTablesDetector();
// tables should be ["my_db1.table1", "my_db2.table2"] in this case
List<String> tables = referredTablesDetector.searchTables(ast);

// we need to implement MetadataService first
MetadataService metadataService = new MetadataService() {
            @Override
            public String getPartitionColName(String tableFullName) {
                // TODO: implement this method
                return null;
            }

            @Override
            public List<String> getTables() {
                // TODO: implement this method
                return null;
            }
        };
String todayDate = "2022-01-01"; // for parsing UDF like today() and yesterday() in the SQL
String targetIP = "127.0.0.1"; // the node to get metadata
ReferredPartitionsDetector referredPartitionsDetector = new ReferredPartitionsDetector(todayDate, targetIp, metadataService);
List<String> partitionRangeList = referredPartitionsDetector.searchTablePartitions(ast);

String sql = "CREATE TABLE my_db.my_tbl (date Date, name String) Engine = Distributed('my_cluster', 'my_db', 'my_tbl_local', rand())";
DistributedTableInfoDetector distributedTableInfoDetector = new DistributedTableInfoDetector();
// clusterName is "my_cluster"
String clusterName = distributedTableInfoDetector.searchCluster(sql);
// tableFullName is "my_db.my_tbl_local"
String tableFullName = distributedTableInfoDetector.searchLocalTableFullName(sql);

String sql = "SELECT t1.id, count(1) as total_count FROM my_db1.table1 t1 LEFT JOIN my_db2.table2 t2 ON t1.id = t2.id GROUP BY t1.id";
AstParser astParser = new AstParser(false);
SelectUnionQuery ast = (SelectUnionQuery) astParser.parse(sql);
GlobalJoinAstRewriter globalJoinAstRewriter = new GlobalJoinAstRewriter();
String rewrittenSql =  globalJoinAstRewriter.visit((INode) ast);
// the rewritten SQL should be:
// SELECT t1.id, count(1) as total_count FROM my_db1.table1 t1 GLOBAL LEFT JOIN my_db2.table2 t2 ON t1.id = t2.id GROUP BY t1.id