The MongoCursorException class

Introduction

Caused by accessing a cursor incorrectly or a error receiving a reply. Note that this can be thrown by any database request that receives a reply, not just queries. Writes, commands, and any other operation that sends information to the database and waits for a response can throw a MongoCursorException. The only exception is new Mongo() (creating a new connection), which will only throw MongoConnectionExceptions.

This returns a specific error message to help diagnose the problem and a numeric error code associated with the cause of the exception.

For example, suppose you tried to insert two documents with the same _id:

error message: E11000 duplicate key error index: foo.bar.$_id_  dup key: { : 1 }
error code: 11000

The following is a list of common errors, codes, and causes. Exact errors are in italics, errors where the message can vary are described in obliques.

• cannot modify cursor after beginning iteration

  Code: 0

  You are calling a method that sets up the query after executing the query. Reset the cursor and try again.

  An example:

  <?php

try {
    $cursor = $collection->find();
    var_dump($cursor->getNext());

    // getNext() queried the database, it's too late to set a limit
    $cursor->limit(1);
}
catch (MongoCursorException $e) {
    echo "error message: ".$e->getMessage()."\n";
    echo "error code: ".$e->getCode()."\n";
}

// this will work, though:
$cursor->getNext();
$cursor->reset();
$cursor->limit(1);

?>

• Get next batch send errors

  Code: 1

  Could not send the query to the database. Make sure the database is still up and the network is okay.

• cursor not found

  Code: 2

  The driver was trying to fetch more results from the database, but the database did not have a record of the query. This usually means that the cursor timed out on the server side: after a few minutes of inactivity, the database will kill a cursor (see MongoCursor::immortal() for information on preventing this).

  An example:

  <?php

try {
    $cursor = $collection->find();
    $cursor->getNext();

    // sleep for 15 minutes
    sleep(60*15);

    while ($cursor->hasNext()) {
        $cursor->getNext();
    }
}
catch (MongoCursorException $e) {
    echo "error message: ".$e->getMessage()."\n";
    echo "error code: ".$e->getCode()."\n";
}

?>

• cursor->buf.pos is null

  Code: 3

  This may indicate you are out of RAM or some other extraordinary circumstance.

• couldn't get response header

  Code: 4

  A common error if the database or network goes down. This means that the driver couldn't get a response from the connection.

• no db response

  Code: 5

  This may not even be an error, for example, the database command "shutdown" returns no response. However, if you were expecting a response, this means the database didn't give one.

• bad response length: %d, did the db assert?

  Code: 6

  This means that the database said that its response was less than 0. This error probably indicates a network error or database corruption.

• incomplete header

  Code: 7

  Highly unusual. Occurs if the database response started out correctly, but broke off in the middle. Probably indicates a network problem.

• incomplete response

  Code: 8

  Highly unusual. Occurs if the database response started out correctly, but broke off in the middle. Probably indicates a network problem.

• couldn't find a response

  Code: 9

  If the response was cached and now cannot be located.

• error getting socket

  Code: 10

  The socket was closed or encountered an error. The driver should automatically reconnect (if possible) on the next operation.

• couldn't find reply, please try again

  Code: 11

  The driver saves any database responses it cannot immediately match with a request. This exception occurs if the driver has already passed your request's response and cannot find your response in its cache.

• error getting database response: errstr

  WSA error getting database response: errstr

  "errstr" is an io error reported directly from the C socket subsystem. On Windows, the error message is prefixed with "WSA".

• Timeout error

  Code: 13

  If there was an error while waiting for a query to complete.

• couldn't send query: <various>

  Code: 14

  C socket error on send.

• max number of retries exhausted, couldn't send query

  Code: 19

  The driver will automatically retry "plain" queries (not commands) a couple of times if the first attempt failed for certain reasons. This is to cause fewer exceptions during replica set failover (although you will probably still have to deal with some) and gloss over transient network issues.

  This can also be caused by the driver not being able to reconnect at all to the database (if, for example, the database is unreachable).

  Version 1.2.2+.

Errors passed through by the database

Database errors should always trigger MongoCursorExceptions on queries. Error messages and codes are sent directly from the database and you should be able to see matching errors in the database log.

A few common database errors are listed below:

• E11000 duplicate key error index: foo.bar.$X dup key: { /* ... */ }

  Code: 11000

  Database error for duplicate keys.

• not master

  Codes: 10107, 13435, and 10058

  Not master errors, piped through by the database. Each of these will cause the driver to disconnect and attempt to find a new master. The actual error you get on failover may not be a "not master" error, depending on when the change in master occurs.

Class synopsis