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| author | Sean McGivern <sean@mcgivern.me.uk> | 2018-07-11 08:32:32 +0000 |
|---|---|---|
| committer | Sean McGivern <sean@mcgivern.me.uk> | 2018-07-11 08:32:32 +0000 |
| commit | 078c824f3be79720c34bf01b0296b5b773afbf64 (patch) | |
| tree | d0c9174aa4fe1f5d4c60cde472562a9ca985014d | |
| parent | c6b670216c6e011e0007a934decdc003a318405b (diff) | |
| parent | 2be54f1bbfc9cfa1e07a88ea581508f251c09853 (diff) | |
| download | gitlab-ce-078c824f3be79720c34bf01b0296b5b773afbf64.tar.gz | |
Merge branch 'fix-doc-on-migration' into 'master'
Fix doc for large table column rename
See merge request gitlab-org/gitlab-ce!20544
| -rw-r--r-- | doc/development/what_requires_downtime.md | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/doc/development/what_requires_downtime.md b/doc/development/what_requires_downtime.md index 47396666879..b668c9de6a0 100644 --- a/doc/development/what_requires_downtime.md +++ b/doc/development/what_requires_downtime.md @@ -198,14 +198,14 @@ And that's it, we're done! ## Changing The Schema For Large Tables While `change_column_type_concurrently` and `rename_column_concurrently` can be -used for changing the schema of a table without downtime it doesn't work very +used for changing the schema of a table without downtime, it doesn't work very well for large tables. Because all of the work happens in sequence the migration can take a very long time to complete, preventing a deployment from proceeding. They can also produce a lot of pressure on the database due to it rapidly updating many rows in sequence. To reduce database pressure you should instead use -`change_column_type_using_background_migration` or `rename_column_concurrently` +`change_column_type_using_background_migration` or `rename_column_using_background_migration` when migrating a column in a large table (e.g. `issues`). These methods work similarly to the concurrent counterparts but uses background migration to spread the work / load over a longer time period, without slowing down deployments. |