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From "Dianne Richards (JIRA)" <j...@apache.org>
Subject [jira] Updated: (OPENJPA-1189) Column names do not contain delimiters when obtained from DatabaseMetaData
Date Tue, 11 Aug 2009 15:42:14 GMT

     [ https://issues.apache.org/jira/browse/OPENJPA-1189?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Dianne Richards updated OPENJPA-1189:
-------------------------------------

    Attachment: patch.txt

Attaching patch for review and possibly commit.

This problem occurred when a column name retrieved from the DB metadata was passed as a parameter
to the Table.getColumn(String name) to retrieve the Column object. The column name retrieved
from the DB does not contain delimiters and this info apparently cannot be obtained. The Table
object was created using input metadata from annotations and xml, and might contain delimiters
for the Map keys. Therefore, the name might not be found. So, the fix is to delimit the input
name if it is initially not found.

Changes were made in the Table getColumn() and containsColumn() methods to take DBDictionary
as a parameter, from which the DB-specific delimiter is retrieved. However, some calling methods
do not currently have access to the DBDictioinary and pass in null. In this scenario, the
double-quote is used as the delimiter. While this is spec-complient, this may not work for
some dbs, which is not good. So, I've opened jira OPENJPA-1236 to handle this in the future.
I suspect some chaining of changes in method signatures to allow a DBDictionary parameter
will fix this.

> Column names do not contain delimiters when obtained from DatabaseMetaData
> --------------------------------------------------------------------------
>
>                 Key: OPENJPA-1189
>                 URL: https://issues.apache.org/jira/browse/OPENJPA-1189
>             Project: OpenJPA
>          Issue Type: Bug
>          Components: jdbc
>    Affects Versions: 2.0.0
>         Environment: DB2 (could exist on other databases)
>            Reporter: Michael Dick
>            Assignee: Dianne Richards
>         Attachments: patch.txt
>
>
> The DatabaseMetaData returned by DB2 does not include delimiters for column names which
include whitespace. This causes potential duplicate column names if we merge into an existing
schema.
> The problem can be illustrated by running the TestManualDelimitedJoinAnnotations test
twice sequentially. The first time the test is executed the database will be clean (presumably)
and everything will work. Subsequent executions read the existing column information from
the database (non delimited) and end up creating a duplicate column.
> Example stacktrace : 
>  <openjpa-2.0.0-SNAPSHOT-r422266:794075M nonfatal general error> org.apache.openjpa.persistence.PersistenceException:
DB2 SQL Error: SQLCODE=-104, SQLSTATE=42601, SQLERRMC=);entityCs_c id OTHER;<references_spec>,
DRIVER=3.50.152 {stmnt 10751758 CREATE TABLE "delim id"."c d" ("entityCs_c id" INTEGER, ENTITYDS_ID
INTEGER, entityCs_c id OTHER)} [code=-104, state=42601]
> 	at org.apache.openjpa.jdbc.meta.MappingTool.record(MappingTool.java:553)
> 	at org.apache.openjpa.jdbc.meta.MappingTool.record(MappingTool.java:453)
>        <snip>
> To resolve the problem we can detect a column / table / schema name which contains whitespace
and add the appropriate delimiters (when the name is provided by the database). One place
to make this change is in DBDictionary.newColumn() 
>     protected Column newColumn(ResultSet colMeta)
>         throws SQLException {
>         Column c = new Column();
>         c.setSchemaName(colMeta.getString("TABLE_SCHEM"));
>         c.setTableName(colMeta.getString("TABLE_NAME"));
>         c.setName(colMeta.getString("COLUMN_NAME"));  // detect whether we need delimiters
and add them
> It's also worth noting that the testcase drops the offending table and then recreates
it. There may be a larger issue where the metadata is cached improperly (could be DB2 specific).

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