The MongoCommandCursor class

(PECL mongo >=1.5.0)

简介

A command cursor is similar to a MongoCursor except that you use it for iterating through the results of a database command instead of a normal query. Command cursors are useful for iterating over large result sets that might exceed the document size limit (currently 16MB) of a single MongoDB::command() response.

While you can create command cursors using MongoCommandCursor::__construct() or the MongoCommandCursor::createFromDocument() factory method, you will generally want to use command-specific helpers such as MongoCollection::aggregateCursor().

Note that the cursor does not "contain" the database command's results; it just manages iteration through them. Thus, if you print a cursor (f.e. with var_dump() or print_r()), you will see the cursor object but not the result documents.

Cursor Stages

A MongoCommandCursor has two "life stages": pre- and post- command. When a cursor is created, it has not yet contacted the database, so it is in its pre-command state. When the client first attempts to get a result (by calling MongoCommandCursor::rewind(), directly or indirectly), the cursor moves into the post-command state.

The command cursor's batch size and socket timeout may be configured in both the pre- and post- command states.

Example #1 Adding options to MongoCommandCursor

<?php

$cursor = new MongoCommandCursor(...);

$cursor = $cursor->batchSize( 4 );

foreach ($cursor as $result) {
    var_dump($result);
}
?>

类摘要

MongoCommandCursor implements MongoCursorInterface , Iterator {
/* 方法 */
public MongoCommandCursor batchSize ( int $batchSize )
public __construct ( MongoClient $connection , string $ns , array $command = array() )
public static MongoCommandCursor createFromDocument ( MongoClient $connection , string $hash , array $document )
public array current ( void )
public bool dead ( void )
public array getReadPreference ( void )
public array info ( void )
public int key ( void )
public void next ( void )
public array rewind ( void )
public MongoCommandCursor setReadPreference ( string $read_preference [, array $tags ] )
public MongoCommandCursor timeout ( int $ms )
public bool valid ( void )
}

参见

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