From cf9d9d865daee2f3c0dd549afa3b168a8e1e679e Mon Sep 17 00:00:00 2001 From: Valery Sizov Date: Thu, 18 May 2017 11:35:59 +0300 Subject: [Migration guide] Add note about prefering change_column_null over change_column --- doc/development/what_requires_downtime.md | 2 ++ 1 file changed, 2 insertions(+) diff --git a/doc/development/what_requires_downtime.md b/doc/development/what_requires_downtime.md index 8da6ad684f5..c4830322fa8 100644 --- a/doc/development/what_requires_downtime.md +++ b/doc/development/what_requires_downtime.md @@ -139,6 +139,8 @@ Adding or removing a NOT NULL clause (or another constraint) can typically be done without requiring downtime. However, this does require that any application changes are deployed _first_. Thus, changing the constraints of a column should happen in a post-deployment migration. +NOTE: Avoid using `change_column` as it produces inefficient query because it re-defines +the whole column type. For example, to add a NOT NULL constraint, prefer `change_column_null ` ## Changing Column Types -- cgit v1.2.1