laravel-spanner

Laravel database driver for Google Cloud Spanner

Requirements

PHP >= 8.0
Laravel >= 10
gRPC extension
protobuf extension (not required, but strongly recommended)

Installation

Put JSON credential file path to env variable: GOOGLE_APPLICATION_CREDENTIALS

export GOOGLE_APPLICATION_CREDENTIALS=/path/to/key.json

Install via composer

composer require colopl/laravel-spanner

Add connection config to config/database.php

[
    'connections' => [
        'spanner' => [
            'driver' => 'spanner',
            'instance' => '<Cloud Spanner instanceId here>',
            'database' => '<Cloud Spanner database name here>',
        ]
    ]
];

That's all. You can use database connection as usual.

$conn = DB::connection('spanner');
$conn->...

Additional Configurations

You can pass SpannerClient config and CacheSessionPool options as below. For more information, please see Google Client Library docs

[
    'connections' => [
        'spanner' => [
            'driver' => 'spanner',
            'instance' => '<Cloud Spanner instanceId here>',
            'database' => '<Cloud Spanner database name here>',
            
            // Spanner Client configurations
            'client' => [
                'projectId' => 'xxx',
                ...
            ],
            
            // CacheSessionPool options
            'session_pool' => [
                'minSessions' => 10,
                'maxSessions' => 500,
            ],
        ]
    ]
];

Unsupported features

STRUCT data types
Explicit Read-only transaction (snapshot)

Limitations

Migrations

Most functions of SchemaBuilder (eg, Schema facade, and Blueprint) can be used. However, artisan migrate command does not work since AUTO_INCREMENT does not exist in Google Cloud Spanner.

Eloquent

If you use interleaved keys, you MUST define them in the interleaveKeys property or you won't be able to save. For more detailed instructions, see Colopl\Spanner\Tests\Eloquent\ModelTest.

Additional Information

Transactions

Google Cloud Spanner sometimes requests transaction retries (e.g. UNAVAILABLE, and ABORTED), even if the logic is correct. For that reason, please do not manage transactions manually.

You should always use the transaction method which handles retry requests internally.

// BAD: Do not use transactions manually!!
try {
    DB::beginTransaction();
    ...
    DB::commit();
} catch (\Throwable $ex) {
    DB::rollBack();
}

// GOOD: You should always use transaction method
DB::transaction(function() {
    ...
});

Google Cloud Spanner creates transactions for all data operations even if you do not explicitly create transactions.

In particular, in the SELECT statement, the type of transaction varies depending on whether it is explicit or implicit.

// implicit transaction (Read-only transaction)
$conn->select('SELECT ...');

// explicit transaction (Read-write transaction)
$conn->transaction(function() {
    $conn->select('SELECT ...');
});

// implicit transaction (Read-write transaction)
$conn->insert('INSERT ...');

// explicit transaction (Read-write transaction)
$conn->transaction(function() {
    $conn->insert('INSERT ...');
});

Transaction type	SELECT statement	INSERT/UPDATE/DELETE statement
implicit transaction	Read-only transaction with singleUse option	Read-write transaction with singleUse option
explicit transaction	Read-write transaction	Read-write transaction

For more information, see Cloud Spanner Documentation about transactions

Stale reads

You can use Stale reads (timestamp bounds) as below.

// There are four types of timestamp bounds: ExactStaleness, MaxStaleness, MinReadTimestamp and ReadTimestamp.
$timestampBound = new ExactStaleness(10);

// by Connection
$connection->selectWithTimestampBound('SELECT ...', $bindings, $timestampBound);

// by Query Builder
$queryBuilder
    ->withStaleness($timestampBound)
    ->get();

Stale reads always runs as read-only transaction with singleUse option. So you can not run as read-write transaction.

Data Types

Some data types of Google Cloud Spanner does not have corresponding built-in type of PHP. You can use following classes by Google Cloud PHP Client

DATE: Google\Cloud\Spanner\Date
BYTES: Google\Cloud\Spanner\Bytes
TIMESTAMP: Google\Cloud\Spanner\Timestamp

Google\Cloud\Spanner\Timestamp is a DateTime representation with UTC timezone and nanoseconds. In laravel-spanner QueryBuilder converts Timestamp in the fetched rows to Carbon with the default timezone in PHP.

Note that if you execute a query without QueryBuilder, it will not have a conversion to Carbon.

Partitioned DML

You can run partitioned DML as below.

// by Connection
$connection->runPartitionedDml('UPDATE ...');


// by Query Builder
$queryBuilder->partitionedUpdate($values);
$queryBuilder->partitionedDelete();

However, Partitioned DML has some limitations. See Cloud Spanner Documentation about Partitioned DML for more information.

Interleave

You can define interleaved tables as below.

$schemaBuilder->create('user_items', function (Blueprint $table) {
    $table->uuid('user_id');
    $table->uuid('id');
    $table->uuid('item_id');
    $table->integer('count');
    $table->timestamps();

    $table->primary(['user_id', 'id']);
    
    // interleaved table
    $table->interleave('users')->cascadeOnDelete();
    
    // interleaved index
    $table->index(['userId', 'created_at'])->interleave('users');
});

Row Deletion Policy

You can define row deletion policy as below.

$schemaBuilder->create('user', function (Blueprint $table) {
    $table->uuid('user_id');
    $table->timestamps();
    
    // create a policy
    $table->deleteRowsOlderThan(['updated_at'], 365);
});

$schemaBuilder->table('user', function (Blueprint $table) {
    // replace policy
    $table->replaceRowDeletionPolicy('udpated_at', 100);

    // drop policy
    $table->dropRowDeletionPolicy();
});

Secondary Index Options

You can define Spanner specific index options like null filtering and storing as below.

$schemaBuilder->table('user_items', function (Blueprint $table) {
    $table->index('userId')
        // Interleave in parent table
        ->interleave('user')
        // Add null filtering
        ->nullFiltered()
        // Add storing
        ->storing(['itemId', 'count']);
});

Mutations

You can insert, update, and delete data using mutations to modify data instead of using DML to improve performance.

$queryBuilder->insertUsingMutation($values);
$queryBuilder->updateUsingMutation($values);
$queryBuilder->deleteUsingMutation($values);

Please note that mutation api does not work the same way as DML. All mutations calls within a transaction are queued and sent as batch at the time you commit. This means that if you make any modifications through the above functions and then try to SELECT the same records before committing, the returned results will not include any of the modifications you've made inside the transaction.

SessionPool and AuthCache

In order to improve the performance of the first connection per request, we use AuthCache and CacheSessionPool.

By default, laravel-spanner uses Filesystem Cache Adapter as the caching pool. If you want to use your own caching pool, you can extend ServiceProvider and inject it into the constructor of Colopl\Spanner\Connection.

'Session not found' exception handling

There are a few cases when a 'Session not found' error can happen:

Scripts that idle too long - for example, a Laravel queue worker or anything that doesn't call Spanner frequently enough (more than once an hour).
The session is more than 28 days old.
Some random flukes on Google's side.

The errors can be handled by one of the supported modes:

MAINTAIN_SESSION_POOL - When the 'session not found' error is encountered, the library tries to disconnect, maintain a session pool (to remove outdated sessions), reconnect, and then try querying again. The mode is enabled by default, but you can enable it explicitly via congifuration:

        'spanner' => [
            'driver' => 'spanner',
        ...
            'sessionNotFoundErrorMode' => 'MAINTAIN_SESSION_POOL',
        ]

CLEAR_SESSION_POOL (default) - The MAINTAIN_SESSION_POOL mode is tried first. If the error still happens, then the clearing of the session pool is enforced and the query is tried once again. As a consequence of session pool clearing, all processes that share the current session pool will be forced to use the new session on the next call.

        'spanner' => [
            'driver' => 'spanner',
        ...
            'sessionNotFoundErrorMode' => 'CLEAR_SESSION_POOL'
        ]

THROW_EXCEPTION - The QueryException is raised and the client code is free to handle it by itself.:

        'spanner' => [
            'driver' => 'spanner',
        ...
            'sessionNotFoundErrorMode' => 'THROW_EXCEPTION',
        ]

Please note, that getDatabaseContext()->execute(...)->rows() returns a /Generator object, which only accesses Spanner when iterated. That affects cursor() and cursorWithTimestampBound() functions and many low-level calls. So you might still get Google\Cloud\Core\Exception\NotFoundException when trying to resolve cursor. To avoid that, please run cursor* functions inside explicit transactions so statements will repeat on error.

$conn->transaction(function () use ($conn) {
    $cursor = $conn->cursor('SELECT ...');

    foearch ($cursor as $value) { ...
});

Queue Worker

After every job is processed, the connection will be disconnected so the session can be released into the session pool. This allows the session to be renewed (through maintainSessionPool()) or expire.

Laravel Tinker

You can use Laravel Tinker with commands such as php artisan tinker. But your session may hang when accessing Cloud Spanner. This is known gRPC issue that occurs when PHP forks a process. The workaround is to add following line to php.ini.

grpc.enable_fork_support=1

Development

Testing

You can run tests on docker by the following command. Note that some environment variables must be set. In order to set the variables, rename .env.sample to .env and edit the values of the defined variables.

Name	Value
`GOOGLE_APPLICATION_CREDENTIALS`	The path of the service account key file with access privilege to Google Cloud Spanner instance
`DB_SPANNER_INSTANCE_ID`	Instance ID of your Google Cloud Spanner
`DB_SPANNER_DATABASE_ID`	Name of the database with in the Google Cloud Spanner instance
`DB_SPANNER_PROJECT_ID`	Not required if your credential includes the project ID

make test

License

Apache 2.0 - See LICENSE for more information.

tyabu12 / laravel-spanner