Client-side timestamps

Cassandra uses timestamps to serialize write operations. That is, values with more current timestamps are considered to be the most up-to-date version of that information. By default, timestamps are assigned by Cassandra on the server-side (Dse\TimestampGenerator\ServerSide()). The PHP Driver also allows for timestamps to be assigned client-side in two ways:

• By providing a client-side timestamp generator such as Dse\TimestampGenerator\Monotonic().
• Explicitly assigning a ‘timestamp’ when executing a statement or batch using execution options.

Background

Given

a running Cassandra cluster

And

the following schema:

CREATE KEYSPACE simplex WITH replication = {
  'class': 'SimpleStrategy',
  'replication_factor': 1
};
USE simplex;
CREATE TABLE playlists (
  id uuid,
  title text,
  album text,
  artist text,
  song_id uuid,
  PRIMARY KEY (id, title, album, artist)
);

Create a simple statement with a client-side timestamp

Given

the following example:

$cluster   = Dse::cluster()->build();
$session   = $cluster->connect("simplex");

$arguments = array(
    'song_id' => new Dse\Uuid('756716f7-2e54-4715-9f00-91dcbea6cf50'),
    'title'   => 'La Petite Tonkinoise',
    'album'   => 'Bye Bye Blackbird',
    'artist'  => 'Joséphine Baker'
);
$options = array(
    'arguments' => $arguments,
    'timestamp' => 1234
);
$session->execute(
    "INSERT INTO playlists (id, song_id, artist, title, album) " .
    "VALUES (62c36092-82a1-3a00-93d1-46196ee77204, ?, ?, ?, ?)",
    $options
);

$result = $session->execute("SELECT artist, title, album, WRITETIME(song_id) FROM simplex.playlists");

foreach ($result as $row) {
    echo "{$row['artist']}: {$row['title']} / {$row['album']} ({$row['writetime(song_id)']})" . PHP_EOL;
}

When

it is executed

Then

its output should contain:

Joséphine Baker: La Petite Tonkinoise / Bye Bye Blackbird (1234)

Create a batch with a client-side timestamp

Given

the following example:

$cluster     = Dse::cluster()->build();
$session     = $cluster->connect("simplex");
$insertQuery = "INSERT INTO playlists (id, song_id, artist, title, album) " .
               "VALUES (62c36092-82a1-3a00-93d1-46196ee77204, ?, ?, ?, ?)";
$prepared    = $session->prepare($insertQuery);
$batch       = new Dse\BatchStatement(Dse::BATCH_LOGGED);

$batch->add($prepared, array(
    'song_id' => new Dse\Uuid('756716f7-2e54-4715-9f00-91dcbea6cf50'),
    'title'   => 'La Petite Tonkinoise',
    'album'   => 'Bye Bye Blackbird',
    'artist'  => 'Joséphine Baker'
));

$batch->add($insertQuery, array(
    new Dse\Uuid('f6071e72-48ec-4fcb-bf3e-379c8a696488'),
    'Willi Ostermann', 'Die Mösch', 'In Gold',
));

$batch->add($prepared, array(
    new Dse\Uuid('fbdf82ed-0063-4796-9c7c-a3d4f47b4b25'),
    'Mick Jager', 'Memo From Turner', 'Performance'
));

$options = array("timestamp" => 5678);

$session->execute($batch, $options);

$result = $session->execute("SELECT artist, title, album, WRITETIME(song_id) FROM simplex.playlists");

foreach ($result as $row) {
    echo "{$row['artist']}: {$row['title']} / {$row['album']} ({$row['writetime(song_id)']})" . PHP_EOL;
}

When

it is executed

Then

its output should contain:

Joséphine Baker: La Petite Tonkinoise / Bye Bye Blackbird (5678)

And

its output should contain:

Willi Ostermann: Die Mösch / In Gold (5678)

And

its output should contain:

Mick Jager: Memo From Turner / Performance (5678)

Create a new session using a timestamp generator

Given

the following example:

$cluster   = Dse::cluster()
               ->withTimestampGenerator(new Dse\TimestampGenerator\Monotonic())
               ->build();
$session   = $cluster->connect("simplex");

for ($i = 0; $i < 10; $i++) {
    $arguments = array(
        'song_id' => new Dse\Uuid("756716f7-2e54-4715-9f00-91dcbea6cf5$i"),
        'title'   => 'La Petite Tonkinoise',
        'album'   => 'Bye Bye Blackbird',
        'artist'  => 'Joséphine Baker'
    );
    $options = array(
        'arguments' => $arguments,
        'timestamp' => 1234
    );
    $session->execute(
        "INSERT INTO playlists (id, song_id, artist, title, album) " .
        "VALUES (62c36092-82a1-3a00-93d1-46196ee77204, ?, ?, ?, ?)",
        $options
    );
}

$result = $session->execute("SELECT artist, title, album, song_id FROM simplex.playlists");

foreach ($result as $row) {
    echo "{$row['artist']}: {$row['title']} / {$row['album']} ({$row['song_id']})" . PHP_EOL;
}

When

it is executed

Then

its output should contain:

Joséphine Baker: La Petite Tonkinoise / Bye Bye Blackbird (756716f7-2e54-4715-9f00-91dcbea6cf59)