Getting ambiguous result using JDBC Metadata API for Hive - jdbc

Question

I am trying to get Table names for hive using DatabaseMetaData in a similar way like RDBMS.
Sample code:
try (Connection con = getJdbcConnection(connectionUri, driverName, username, password);) {
DatabaseMetaData metadata = con.getMetaData();
ResultSet rs = metadata.getTables(null, null, tableName, null);
while (rs.next()) {
System.out.println(rs.getString(3));
}
} catch (SQLException e) {
}
private static void registerDriver(String driverName) {
try {
Class.forName(driverName);
} catch (ClassNotFoundException e) {
LOG.error("No class found for " + driverName + ". Details: " + e);
}
}
private static Connection getJdbcConnection(String connectionUri, String driverName, String username,
String password) throws SQLException{
registerDriver(driverName);
return DriverManager.getConnection(connectionUri, username,password);
}
There is no table in a particular database. Using different different table names, I am getting different output.
For example:
I put table name emp, there are 3 records with name emp
I put table name employee, there are 5 records with name employee
I put table name emp12, it is returning no records (which is expected)
Am I doing something wrong?
Shouldn't I use DatabaseMetaData for checking table existence?

Answer 1

I need to pass schema name in getTables method
Signature:
ResultSet getTables(String catalog,
String schemaPattern,
String tableNamePattern,
String[] types)
throws SQLException
I passed following agruments:
catalog = null;
schemaPattern = Hive schema Name
tableNamePattern = Hive Table Name
types = new String[] { "TABLE" }
Sample code:
try (Connection con = getJdbcConnection(connectionUri, driverName, username, password);) {
DatabaseMetaData metadata = con.getMetaData();
ResultSet rs = metadata.getTables(null, schemaName, tableName, new String[] { "TABLE" });
while (rs.next()) {
String tName = rs.getString("TABLE_NAME");
if (tName != null && tName.equals(tableName)) {
LOG.info("Table [" + tableName + "] is present in the Database.");
return true;
}
}
rs.close();
LOG.info("Table [" + tableName + "] is not present in the Database.");
return false;
} catch (SQLException e) {
LOG.error("Not able to get Table Metadata . Caused By: " + e);
}