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| author | Achilleas Pipinellis <axilleas@axilleas.me> | 2016-08-10 17:15:16 +0300 |
|---|---|---|
| committer | Achilleas Pipinellis <axilleas@axilleas.me> | 2016-08-10 17:15:16 +0300 |
| commit | ae2d3c417075c83e169ab7662f3dd11e3b2bf043 (patch) | |
| tree | acd0a5bb1af3323e72d55916ac09a3b63dcee602 | |
| parent | b50e8c293452f65990f1a97050b474c95755b660 (diff) | |
| parent | ee451ea5739c5d574a5c3c7db36c5a4c28206fd5 (diff) | |
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
| -rw-r--r-- | doc/development/what_requires_downtime.md | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/doc/development/what_requires_downtime.md b/doc/development/what_requires_downtime.md index abd693cf72d..2574c2c0472 100644 --- a/doc/development/what_requires_downtime.md +++ b/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 |