46 lines
1.8 KiB
Markdown
46 lines
1.8 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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# Maintenance operations
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This page details various database related operations that may relate to development.
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## Disabling an index
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There are certain situations in which you might want to disable an index before removing it:
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- The index is on a large table and rebuilding it in the case of a revert would take a long time.
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- It is uncertain whether or not the index is being used in ways that are not fully visible.
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To disable an index before removing it:
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1. Open a [production infrastructure issue](https://gitlab.com/gitlab-com/gl-infra/production/-/issues/new)
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and use the "Production Change" template.
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1. Inform the database team in the issue `@gl-database` or in Slack `#database`.
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1. Add a step to verify the index is used (this would likely be an `EXPLAIN` command known to use the index).
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1. Add the step to disable the index:
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```sql
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UPDATE pg_index SET indisvalid = false WHERE indexrelid = 'index_issues_on_foo'::regclass;
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```
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1. Add a step to verify the index is invalid (this would likely be the same as used to verify before disabling the index).
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1. Verify the index is invalid on replicas:
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```sql
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SELECT indisvalid FROM pg_index WHERE indexrelid = 'index_issues_on_foo'::regclass;
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```
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1. Add steps for rolling back the invalidation:
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1. Rollback the index invalidation
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```sql
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UPDATE pg_index SET indisvalid = true WHERE indexrelid = 'index_issues_on_foo'::regclass;
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```
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1. Verify the index is being used again.
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See this [example infrastructure issue](https://gitlab.com/gitlab-com/gl-infra/production/-/issues/2795) for reference.
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