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From "Unico Hommes (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (JCR-3261) Problems with BundleDbPersistenceManager getAllNodeIds
Date Sat, 17 Mar 2012 18:47:38 GMT

     [ https://issues.apache.org/jira/browse/JCR-3261?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Unico Hommes updated JCR-3261:
------------------------------

    Description: 
When using MySQL:
The problem arises when the method parameter maxcount is less than the total amount of records
in the bundle table.

First of all I found out that mysql orders the nodeid objects different than jackrabbit does.
The following test describes this idea:

    public void testMySQLOrderByNodeId() throws Exception {
        NodeId nodeId1 = new NodeId("7ff9e87c-f87f-4d35-9d61-2e298e56ac37");
        NodeId nodeId2 = new NodeId("9fd0d452-b5d0-426b-8a0f-bef830ba0495");

        PreparedStatement stmt = connection.prepareStatement("SELECT NODE_ID FROM DEFAULT_BUNDLE
WHERE NODE_ID = ? OR NODE_ID = ? ORDER BY NODE_ID");

        Object[] params = new Object[] { nodeId1.getRawBytes(), nodeId2.getRawBytes() };
        stmt.setObject(1, params[0]);
        stmt.setObject(2, params[1]);

        ArrayList<NodeId> nodeIds = new ArrayList<NodeId>();
        ResultSet resultSet = stmt.executeQuery();
        while(resultSet.next()) {
            NodeId nodeId = new NodeId(resultSet.getBytes(1));
            System.out.println(nodeId);
            nodeIds.add(nodeId);
        }
        Collections.sort(nodeIds);
        for (NodeId nodeId : nodeIds) {
            System.out.println(nodeId);
        }
    }

Which results in the following output:

7ff9e87c-f87f-4d35-9d61-2e298e56ac37
9fd0d452-b5d0-426b-8a0f-bef830ba0495
9fd0d452-b5d0-426b-8a0f-bef830ba0495
7ff9e87c-f87f-4d35-9d61-2e298e56ac37


Now the problem with the getAllNodeIds method is that it fetches an extra 10 records on top
of maxcount (to avoid a problem where the first key is not the one you that is wanted). Afterwards
it skips a number of records again, this time using nodeid.compareto. This compareto statement
returns true unexpectedly for mysql because the code doesn't expect the mysql ordering.

I had the situation where I had about 17000 records in the bundle table but consecutively
getting the ids a thousand records at a time returned only about 8000 records in all.

With Derby DB there is an infinite loop when it is used as it is for instance by ConsistencyCheckerImpl.
This is because of the bundleSelectAllIdsFromSQL sql query that is done in the case of SM_LONGLONG_KEYS
which is used in the case of Derby. Compare for instance that statement with the corresponding
statement for SM_BINARY_KEYS. You will see that the former uses >= while the latter only
>. The latter is correct. We want only records that are bigger than the passed in parameter,
not bigger or equal.


  was:
The problem arises when the method parameter maxcount is less than the total amount of records
in the bundle table.

First of all I found out that mysql orders the nodeid objects different than jackrabbit does.
The following test describes this idea:

    public void testMySQLOrderByNodeId() throws Exception {
        NodeId nodeId1 = new NodeId("7ff9e87c-f87f-4d35-9d61-2e298e56ac37");
        NodeId nodeId2 = new NodeId("9fd0d452-b5d0-426b-8a0f-bef830ba0495");

        PreparedStatement stmt = connection.prepareStatement("SELECT NODE_ID FROM DEFAULT_BUNDLE
WHERE NODE_ID = ? OR NODE_ID = ? ORDER BY NODE_ID");

        Object[] params = new Object[] { nodeId1.getRawBytes(), nodeId2.getRawBytes() };
        stmt.setObject(1, params[0]);
        stmt.setObject(2, params[1]);

        ArrayList<NodeId> nodeIds = new ArrayList<NodeId>();
        ResultSet resultSet = stmt.executeQuery();
        while(resultSet.next()) {
            NodeId nodeId = new NodeId(resultSet.getBytes(1));
            System.out.println(nodeId);
            nodeIds.add(nodeId);
        }
        Collections.sort(nodeIds);
        for (NodeId nodeId : nodeIds) {
            System.out.println(nodeId);
        }
    }

Which results in the following output:

7ff9e87c-f87f-4d35-9d61-2e298e56ac37
9fd0d452-b5d0-426b-8a0f-bef830ba0495
9fd0d452-b5d0-426b-8a0f-bef830ba0495
7ff9e87c-f87f-4d35-9d61-2e298e56ac37


Now the problem with the getAllNodeIds method is that it fetches an extra 10 records on top
of maxcount (to avoid a problem where the first key is not the one you that is wanted). Afterwards
it skips a number of records again, this time using nodeid.compareto. This compareto statement
returns true unexpectedly for mysql because the code doesn't expect the mysql ordering.

I had the situation where I had about 17000 records in the bundle table but consecutively
getting the ids a thousand records at a time returned only about 8000 records in all.

I'll attach a patch that fixes the problem.

        Summary: Problems with BundleDbPersistenceManager getAllNodeIds  (was: BundleDbPersistenceManager
getAllIds gives wrong amount of results for MySQL)

Updated title and description because another problem with the same method was found for Derby
DB. Attaching an updated patch.
                
> Problems with BundleDbPersistenceManager getAllNodeIds
> ------------------------------------------------------
>
>                 Key: JCR-3261
>                 URL: https://issues.apache.org/jira/browse/JCR-3261
>             Project: Jackrabbit Content Repository
>          Issue Type: Bug
>    Affects Versions: 2.4
>            Reporter: Unico Hommes
>             Fix For: 2.4.1
>
>         Attachments: bdbpm_allids.patch
>
>
> When using MySQL:
> The problem arises when the method parameter maxcount is less than the total amount of
records in the bundle table.
> First of all I found out that mysql orders the nodeid objects different than jackrabbit
does. The following test describes this idea:
>     public void testMySQLOrderByNodeId() throws Exception {
>         NodeId nodeId1 = new NodeId("7ff9e87c-f87f-4d35-9d61-2e298e56ac37");
>         NodeId nodeId2 = new NodeId("9fd0d452-b5d0-426b-8a0f-bef830ba0495");
>         PreparedStatement stmt = connection.prepareStatement("SELECT NODE_ID FROM DEFAULT_BUNDLE
WHERE NODE_ID = ? OR NODE_ID = ? ORDER BY NODE_ID");
>         Object[] params = new Object[] { nodeId1.getRawBytes(), nodeId2.getRawBytes()
};
>         stmt.setObject(1, params[0]);
>         stmt.setObject(2, params[1]);
>         ArrayList<NodeId> nodeIds = new ArrayList<NodeId>();
>         ResultSet resultSet = stmt.executeQuery();
>         while(resultSet.next()) {
>             NodeId nodeId = new NodeId(resultSet.getBytes(1));
>             System.out.println(nodeId);
>             nodeIds.add(nodeId);
>         }
>         Collections.sort(nodeIds);
>         for (NodeId nodeId : nodeIds) {
>             System.out.println(nodeId);
>         }
>     }
> Which results in the following output:
> 7ff9e87c-f87f-4d35-9d61-2e298e56ac37
> 9fd0d452-b5d0-426b-8a0f-bef830ba0495
> 9fd0d452-b5d0-426b-8a0f-bef830ba0495
> 7ff9e87c-f87f-4d35-9d61-2e298e56ac37
> Now the problem with the getAllNodeIds method is that it fetches an extra 10 records
on top of maxcount (to avoid a problem where the first key is not the one you that is wanted).
Afterwards it skips a number of records again, this time using nodeid.compareto. This compareto
statement returns true unexpectedly for mysql because the code doesn't expect the mysql ordering.
> I had the situation where I had about 17000 records in the bundle table but consecutively
getting the ids a thousand records at a time returned only about 8000 records in all.
> With Derby DB there is an infinite loop when it is used as it is for instance by ConsistencyCheckerImpl.
This is because of the bundleSelectAllIdsFromSQL sql query that is done in the case of SM_LONGLONG_KEYS
which is used in the case of Derby. Compare for instance that statement with the corresponding
statement for SM_BINARY_KEYS. You will see that the former uses >= while the latter only
>. The latter is correct. We want only records that are bigger than the passed in parameter,
not bigger or equal.

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