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diff --git a/doc/development/swapping_tables.md b/doc/development/swapping_tables.md index efb481ccf35..eaa6568dc36 100644 --- a/doc/development/swapping_tables.md +++ b/doc/development/swapping_tables.md @@ -1,51 +1,11 @@ --- -stage: Data Stores -group: Database -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 +redirect_to: 'database/swapping_tables.md' +remove_date: '2022-11-04' --- -# Swapping Tables +This document was moved to [another location](database/swapping_tables.md). -Sometimes you need to replace one table with another. For example, when -migrating data in a very large table it's often better to create a copy of the -table and insert & migrate the data into this new table in the background. - -Let's say you want to swap the table `events` with `events_for_migration`. In -this case you need to follow 3 steps: - -1. Rename `events` to `events_temporary` -1. Rename `events_for_migration` to `events` -1. Rename `events_temporary` to `events_for_migration` - -Rails allows you to do this using the `rename_table` method: - -```ruby -rename_table :events, :events_temporary -rename_table :events_for_migration, :events -rename_table :events_temporary, :events_for_migration -``` - -This does not require any downtime as long as the 3 `rename_table` calls are -executed in the _same_ database transaction. Rails by default uses database -transactions for migrations, but if it doesn't you need to start one -manually: - -```ruby -Event.transaction do - rename_table :events, :events_temporary - rename_table :events_for_migration, :events - rename_table :events_temporary, :events_for_migration -end -``` - -Once swapped you _have to_ reset the primary key of the new table. For -PostgreSQL you can use the `reset_pk_sequence!` method like so: - -```ruby -reset_pk_sequence!('events') -``` - -Failure to reset the primary keys results in newly created rows starting -with an ID value of 1. Depending on the existing data this can then lead to -duplicate key constraints from popping up, preventing users from creating new -data. +<!-- This redirect file can be deleted after <2022-11-04>. --> +<!-- Redirects that point to other docs in the same project expire in three months. --> +<!-- Redirects that point to docs in a different project or site (for example, link is not relative and starts with `https:`) expire in one year. --> +<!-- Before deletion, see: https://docs.gitlab.com/ee/development/documentation/redirects.html --> |