Is there a Java API for comparing Database Schemas

Question

I'd like to compare if

• tables
• columns including datatypes and length/precision.
• indexes and their columns
• constraints

in two database schemas are identical.

Is there anything like this available? Maybe from one of the database migration managing tools?

Answer 1

JDBC is the only Java API that deals with databases.

You'd have to connect to both, get their respective DatabaseMetaData, and compare the two.

Answer 2

LiquiBase has database diff. But I don't know if there is an API, or just the tool.

Answer 3

I don't know a high level API for schema comparison I used DatabaseMetaData it's not to hard to find differences i.g to retieve all tables you can do something like this:

DatabaseMetaData meta = con.getMetaData();
  ResultSet res = meta.getTables(null, null, null, 
     new String[] {"TABLE"});
  System.out.println("List of tables: "); 
  while (res.next()) {
     System.out.println(
        "   "+res.getString("TABLE_CAT") 
       + ", "+res.getString("TABLE_SCHEM")
       + ", "+res.getString("TABLE_NAME")
       + ", "+res.getString("TABLE_TYPE")
       + ", "+res.getString("REMARKS")); 
  }
  res.close();

The following methods are also important for your intention:

getColumns(String catalog, String schemaPattern, String tableNamePattern, String columnNamePattern) 
getExportedKeys(String catalog, String schema, String table)
getIndexInfo(String catalog, String schema, String table, boolean unique, boolean approximate) 
getPrimaryKeys(String catalog, String schema, String table)