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https://issues.apache.org/jira/browse/OPENJPA-592?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12596249#action_12596249
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Jason Zheng commented on OPENJPA-592:
-------------------------------------
>>What does mysql return in the table_cat? In the example above, for example,
>>would the table_cat be "jpa", or something else entirely?
It returns "jpa" for table_cat, and null for table_schem.
Actually these values are set correctly in MySQL information_schema.
mysql> select table_catalog, table_schema from information_schema.columns where
table_name='employe
e' and column_name='name';
+---------------+--------------+
| table_catalog | table_schema |
+---------------+--------------+
| NULL | jpa |
+---------------+--------------+
It seems to me that the MySQL driver swaps the schema and catalog values.
Please see http://forums.mysql.com/read.php?39,137564,137629 for more details.
>> If we override newColumn in MySQLDictionary to use table_cat instead, don't
>> we need to make corresponding changes to all these methods?
Yes, I think so. Actually we have done the same fix for InformixDictionary.
InformixDictionary creates a special field for this problem:
/**
* Informix JDBC metadata for all known drivers returns with the
* table catalog and the table schema name swapped. A <code>true</code>
* value for this property indicates that they should be reversed.
*/
public boolean swapSchemaAndCatalog = true;
and in newColumn, newPrimaryKey, etc:
if (swapSchemaAndCatalog)
col.setSchemaName(colMeta.getString("TABLE_CAT"));
Thanks,
Jason
> In MySQL explicitly specifying openjpa.jdbc.Schema with default schema gives
> an error on first time EM access if mapping is already done
> ----------------------------------------------------------------------------------------------------------------------------------------
>
> Key: OPENJPA-592
> URL: https://issues.apache.org/jira/browse/OPENJPA-592
> Project: OpenJPA
> Issue Type: Bug
> Components: jdbc
> Reporter: Jason Zheng
> Attachments: patch-592.txt
>
>
> Suppose we have an entity "Employee" and we have the following properties
> specified in persistence.xml:
> <property name='openjpa.jdbc.SynchronizeMappings'
> value='buildSchema(ForeignKeys=true)' />
> <property name='openjpa.jdbc.Schema' value='jpa' />
> OpenJPA should create table "jpa:employee" if it does not exist in the
> database, and do nothing if the table already exists.
> But in MySQL, it tries to create the table when the table already exists in
> database, and we will get the following exception because of this:
> <openjpa-1.1.0-SNAPSHOT-r422266:647033 nonfatal general error>
> org.apache.openjpa.persistence.PersistenceException: Table 'employee' already
> exists {stmnt 7294825 CREATE TABLE jpa.employee (id BIGINT NOT NULL, PRIMARY
> KEY (id)) TYPE = innodb} [code=1050, state=42S01]
> at org.apache.openjpa.jdbc.meta.MappingTool.record(MappingTool.java:553)
> at org.apache.openjpa.jdbc.meta.MappingTool.record(MappingTool.java:453)
> at
> org.apache.openjpa.jdbc.kernel.JDBCBrokerFactory.synchronizeMappings(JDBCBrokerFactory.java:159)
> ...
> This is because MySQL doesn't have concept of schema, and the column metadata
> from MySQL doesn't contain schema information. Hence OpenJPA fails to find
> the table although the table exists in database.
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