README

Laravel database driver for Google Cloud Spanner

Requirements

PHP >= 8.1
Laravel >= 10
gRPC extension
protobuf extension (recommended for better performance)
sysvmsg, sysvsem, sysvshm extensions (recommended for better performance)

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,
            ],
        ]
    ]
];

Recommended Setup

Please note that the following are not required, but are strongly recommended for better performance.

Install protobuf pecl extension for faster network communication.
Install sysvmsg, sysvsem, sysvshm extensions for faster session management.
Mount the cache directory (./storage/framework/spanner by default) to tmpfs for better session io performance. Cache path can be changed by setting connections.{name}.cache_path in your config/database.php file.

Unsupported features

STRUCT data types
Inserting/Updating JSON data types
Explicit Read-only transaction (snapshot)

Limitations

SQL Mode

Currently only supports Spanner running GoogleSQL (PostgreSQL mode is not supported).

Eloquent

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

Additional Information

Migrations

Since Cloud Spanner does not support AUTO_INCREMENT attribute, Blueprint::increments (and all of its variants) will create a column of type STRING(36) DEFAULT (GENERATE_UUID()) to generate and fill the column with a UUID and flag it as a primary key.

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 Boost

Data boost creates snapshot and runs the query in parallel without affecting existing workloads.

You can read more about it here.

Below are some examples of how to use it.

// Using Connection
$connection->selectWithOptions('SELECT ...', $bindings, ['dataBoostEnabled' => true]);

// Using Query Builder
$queryBuilder
    ->useDataBoost()
    ->get();

Note

This creates a new session in the background which is not shared with the current session pool. This means, queries running with data boost will not be associated with transactions that may be taking place.

Request Tags and Transaction Tags

Spanner allows you to attach tags to your queries and transactions that can be used for troubleshooting.

You can set request tags and transaction tags as below.

$requestPath = request()->path();
$tag = 'url=' . $requestPath;
$connection->setRequestTag($tag);
$connection->setTransactionTag($tag);

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

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

When fetching rows, the library coverts the following column types

Timestamp -> Carbon with the default timezone in PHP
Numeric -> string

Note that if you execute a query without QueryBuilder, it will not have these conversions.

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->interleaveInParent('users')->cascadeOnDelete();
    
    // interleaved index
    $table->index(['userId', 'created_at'])->interleaveIn('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) {
    // add policy
    $table->addRowDeletionPolicy('udpated_at', 100);

    // replace policy
    $table->replaceRowDeletionPolicy('udpated_at', 100);

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

Sequence

If you want a simple sequence to be used as a primary key, you can use useSequence() method. If useSequence() is called without providing a $name, a sequence with name user_id_sequence will be created with start_with_counter set with a random value between 1 and 1,000,000.

$schemaBuilder->create('user', function (Blueprint $table) {
    $table->integer('id')->useSequence();
});

If you want more flexibility, you can also create, alter, and drop sequences directly as below.

$schemaBuilder->create('user_items', function (Blueprint $table) {
    $table->createSequence('sequence_name');
    $table->integer('id')->useSequence('sequence_name');
    
    $table->alterSequence('sequence_name')
        ->startWithCounter(100)
        ->skipRangeMin(1)
        ->skipRangeMax(10);
    
    $table->dropSequence('sequence_name');
});

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
        ->interleaveIn('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);
$queryBuilder->insertOrUpdateUsingMutation($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, this library 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.

The initialization of each session takes about a second, so warming up the sessions during the boot up phase of your server is recommended. This can be achieved by running the php artisan spanner:warmup command. You can set the number of sessions to warm up by setting the connections.{name}.session_pool.maxSessions option in config/database.php

Similarly, the sessions remain active for 60 minutes after use so deleting the sessions during the shutdown phase of your server is recommended. This can be achieved by running the php artisan spanner:cooldown command.

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.

colopl / laravel-spanner

Maintainers

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