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Commit ae2d3c41 by Achilleas Pipinellis
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Merge branch 'add-column-with-default-to-downtime-guide' into 'master'

Mention add_column_with_default in downtime guide ## What does this MR do? This extends the "What causes downtime" guide with a mention of the `add_column_with_default` migration helper. ## Are there points in the code the reviewer needs to double check? Spelling, grammar, etc. ## Why was this MR needed? Currently the guide may lead one to believe it's not possible at all to add a column with a default value. ## Does this MR meet the acceptance criteria? - [x] ~~[CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added~~ - [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md) - Tests - [ ] All builds are passing - [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides) - [ ] Branch has no merge conflicts with `master` (if you do - rebase it please) - [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits) See merge request !5719
parents b50e8c29 ee451ea5
Showing with 8 additions and 0 deletions
doc/development/what_requires_downtime.md
......@@ -31,6 +31,14 @@ operation, even when using `ALGORITHM=INPLACE` and `LOCK=NONE`. This means
downtime _may_ be required when modifying large tables as otherwise the
operation could potentially take hours to complete.
Adding a column with a default value _can_ be done without requiring downtime
when using the migration helper method
`Gitlab::Database::MigrationHelpers#add_column_with_default`. This method works
similar to `add_column` except it updates existing rows in batches without
blocking access to the table being modified. See ["Adding Columns With Default
Values"](migration_style_guide.html#adding-columns-with-default-values) for more
information on how to use this method.
## Dropping Columns
On PostgreSQL you can safely remove an existing column without the need for
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