1# Google Cloud Spanner
2
3## Usage
4
5See [Google Spanner Documentation](https://cloud.google.com/spanner/docs) for
6more details.
7
8The DSN must be given in the following format.
9
10`spanner://projects/{projectId}/instances/{instanceId}/databases/{databaseName}?param=true`
11
12as described in [README.md#database-urls](../../README.md#database-urls)
13
14| Param | WithInstance Config | Description |
15| ----- | ------------------- | ----------- |
16| `x-migrations-table` | `MigrationsTable` | Name of the migrations table |
17| `x-clean-statements` | `CleanStatements` | Whether to parse and clean DDL statements before running migration towards Spanner (Required for comments and multiple statements) |
18| `url` | `DatabaseName` | The full path to the Spanner database resource. If provided as part of `Config` it must not contain a scheme or query string to match the format `projects/{projectId}/instances/{instanceId}/databases/{databaseName}`|
19| `projectId` || The Google Cloud Platform project id
20| `instanceId` || The id of the instance running Spanner
21| `databaseName` || The name of the Spanner database
22
23> **Note:** Google Cloud Spanner migrations can take a considerable amount of
24> time. The migrations provided as part of the example take about 6 minutes to
25> run on a small instance.
26>
27> ```log
28> 1481574547/u create_users_table (21.354507597s)
29> 1496539702/u add_city_to_users (41.647359754s)
30> 1496601752/u add_index_on_user_emails (2m12.155787369s)
31> 1496602638/u create_books_table (2m30.77299181s)
32
33## DDL with comments
34
35At the moment the GCP Spanner backed does not seem to allow for comments (See https://issuetracker.google.com/issues/159730604)
36so in order to be able to use migration with DDL containing comments `x-clean-stamements` is required
37
38## Multiple statements
39
40In order to be able to use more than 1 DDL statement in the same migration file, the file has to be parsed and therefore the `x-clean-statements` flag is required
41
42## Testing
43
44To unit test the `spanner` driver, `SPANNER_DATABASE` needs to be set. You'll
45need to sign-up to Google Cloud Platform (GCP) and have a running Spanner
46instance since it is not possible to run Google Spanner outside GCP.
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