101 lines
5 KiB
Markdown
101 lines
5 KiB
Markdown
---
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stage: Data Stores
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group: Database
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info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
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---
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# Database Lab and Postgres.ai
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Internal users at GitLab have access to the Database Lab Engine (DLE) and
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[postgres.ai](https://console.postgres.ai/) for testing performance of database queries
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on replicated production data. Unlike a typical read-only production replica, in the DLE you can
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also create, update, and delete rows. You can also test the performance of
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schema changes, like additional indexes or columns, in an isolated copy of production data.
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## Access Database Lab Engine
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Access to the DLE is helpful for:
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- Database reviewers and maintainers.
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- Engineers who work on merge requests that have large effects on databases.
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To access the DLE's services, you can:
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- Perform query testing in the `#database_lab` Slack channel, or in the Postgres.ai web console.
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Employees access both services with their GitLab Google account. Query testing
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provides `EXPLAIN` (analyze, buffers) plans for queries executed there.
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- Migration testing by triggering a job as a part of a merge request.
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- Direct `psql` access to DLE instead of a production replica. Available to authorized users only.
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To request `psql` access, file an [access request](https://about.gitlab.com/handbook/business-technology/team-member-enablement/onboarding-access-requests/access-requests/#individual-or-bulk-access-request).
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For more assistance, use the `#database` Slack channel.
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NOTE:
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If you need only temporary access to a production replica, instead of a Database Lab
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clone, follow the runbook procedure for connecting to the
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[database console with Teleport](https://gitlab.com/gitlab-com/runbooks/-/blob/master/docs/Teleport/Connect_to_Database_Console_via_Teleport.md).
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This procedure is similar to [Rails console access with Teleport](https://gitlab.com/gitlab-com/runbooks/-/blob/master/docs/Teleport/Connect_to_Rails_Console_via_Teleport.md#how-to-use-teleport-to-connect-to-rails-console).
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### Query testing
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You can access Database Lab's query analysis features either:
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- In the `#database_lab` Slack channel. Shows everyone's commands and results, but
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your own commands are still isolated in their own clone.
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- In [the Postgres.ai web console](https://console.postgres.ai/GitLab/joe-instances).
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Shows only the commands you run.
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#### Generate query plans
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Query plans are an essential part of the database review process. These plans
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enable us to decide quickly if a given query can be performant on GitLab.com.
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Running the `explain` command generates an `explain` plan and a link to the Postgres.ai
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console with more query analysis. For example, running `EXPLAIN SELECT * FROM application_settings`
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does the following:
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1. Runs `explain (analyze, buffers) select * from application_settings;` against a database clone.
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1. Responds with timing and buffer details from the run.
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1. Provides a [detailed, shareable report on the results](https://console.postgres.ai/shared/24d543c9-893b-4ff6-8deb-a8f902f85a53).
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#### Making schema changes
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Sometimes when testing queries, a contributor may realize that the query needs an index
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or other schema change to make added queries more performant. To test the query, run the `exec` command.
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For example, running this command:
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```sql
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exec CREATE INDEX on application_settings USING btree (instance_administration_project_id)
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```
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creates the specified index on the table. You can [test queries](#generate-query-plans) leveraging
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the new index. `exec` does not return any results, only the time required to execute the query.
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#### Reset the clone
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After many changes, such as after a destructive query or an ineffective index,
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you must start over. To reset your designated clone, run `reset`.
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### Migration testing
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For information on testing migrations, review our
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[database migration testing documentation](database_migration_pipeline.md).
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### Access the console with `psql`
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Team members with [`psql` access](#access-database-lab-engine), can gain direct access
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to a clone via `psql`. Access to `psql` enables you to see data, not just metadata.
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To connect to a clone using `psql`:
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1. Create a clone from the [desired instance](https://console.postgres.ai/gitlab/instances/).
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1. Provide a **Clone ID**: Something that uniquely identifies your clone, such as `yourname-testing-gitlabissue`.
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1. Provide a **Database username** and **Database password**: Connects `psql` to your clone.
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1. Select **Enable deletion protection** if you want to preserve your clone. Avoid selecting this option.
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Clones are removed after 12 hours.
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1. In the **Clone details** page of the Postgres.ai web interface, copy and run
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the command to start SSH port forwarding for the clone.
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1. In the **Clone details** page of the Postgres.ai web interface, copy and run the `psql` connection string.
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Use the password provided at setup.
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After you connect, use clone like you would any `psql` console in production, but with
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the added benefit and safety of an isolated writeable environment.
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