MongoCursor::tailable
(PECL mongo >=0.9.4)
MongoCursor::tailable — Sets whether this cursor will be left open after fetching the last results
Description
Mongo has a feature known as tailable cursors which are similar to the Unix "tail -f" command.
Tailable means cursor is not closed when the last data is retrieved. Rather, the cursor marks the final object's position. you can resume using the cursor later, from where it was located, if more data were received.
Like any "latent cursor", the cursor may become invalid at some point -- for example if that final object it references were deleted. Thus, you should be prepared to requery if the cursor is MongoCursor::dead().
Parameters
-
tail -
If the cursor should be tailable.
Return Values
Returns this cursor.
Errors/Exceptions
Throws MongoCursorException if this cursor has started iterating.
Examples
Example #1 MongoCursor::tailable() example
<?php
$cursor = $collection->find()->tailable();
$results = array();
while (1) {
if (!$cursor->hasNext()) {
// we've read all the results, exit
if ($cursor->dead()) {
break;
}
// read all results so far, wait for more
sleep(10);
}
else {
$results[] = $cursor->getNext();
}
}
?>
See Also
MongoDB core docs on » tailable cursors.
- MongoCursor::awaitData() - Sets whether this cursor will wait for a while for a tailable cursor to return more data
- PHP Руководство
- Функции по категориям
- Индекс функций
- Справочник функций
- Расширения для работы с базами данных
- Расширения для работы с базами данных отдельных производителей
- MongoDB
- Базовые классы
- Функция MongoCursor::addOption() - Adds a top-level key/value pair to a query
- Функция MongoCursor::awaitData() - Sets whether this cursor will wait for a while for a tailable cursor to return more data
- Функция MongoCursor::batchSize() - Limits the number of elements returned in one batch.
- Функция MongoCursor::__construct() - Create a new cursor
- Функция MongoCursor::count() - Counts the number of results for this query
- Функция MongoCursor::current() - Returns the current element
- Функция MongoCursor::dead() - Checks if there are documents that have not been sent yet from the database for this cursor
- Функция MongoCursor::doQuery() - Execute the query.
- Функция MongoCursor::explain() - Return an explanation of the query, often useful for optimization and debugging
- Функция MongoCursor::fields() - Sets the fields for a query
- Функция MongoCursor::getNext() - Return the next object to which this cursor points, and advance the cursor
- Функция MongoCursor::getReadPreference() - Get the read preference for this query
- Функция MongoCursor::hasNext() - Checks if there are any more elements in this cursor
- Функция MongoCursor::hint() - Gives the database a hint about the query
- Функция MongoCursor::immortal() - Sets whether this cursor will timeout
- Функция MongoCursor::info() - Gets the query, fields, limit, and skip for this cursor
- Функция MongoCursor::key() - Returns the current result's _id
- Функция MongoCursor::limit() - Limits the number of results returned
- Функция MongoCursor::maxTimeMS() - Sets a server-side timeout for this query
- Функция MongoCursor::next() - Advances the cursor to the next result
- Функция MongoCursor::partial() - If this query should fetch partial results from mongos if a shard is down
- Функция MongoCursor::reset() - Clears the cursor
- Функция MongoCursor::rewind() - Returns the cursor to the beginning of the result set
- Функция MongoCursor::setFlag() - Sets arbitrary flags in case there is no method available the specific flag
- Функция MongoCursor::setReadPreference() - Set the read preference for this query
- Функция MongoCursor::skip() - Skips a number of results
- Функция MongoCursor::slaveOkay() - Sets whether this query can be done on a secondary [deprecated]
- Функция MongoCursor::snapshot() - Use snapshot mode for the query
- Функция MongoCursor::sort() - Sorts the results by given fields
- Функция MongoCursor::tailable() - Sets whether this cursor will be left open after fetching the last results
- Функция MongoCursor::timeout() - Sets a client-side timeout for this query
- Функция MongoCursor::valid() - Checks if the cursor is reading a valid result.
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