Merge branch 'integer_migration_style' into 'master'

Integer migration style

See merge request !6334

1 files changed, 22 insertions, 0 deletions

diff --git a/doc/development/migration_style_guide.md b/doc/development/migration_style_guide.md
index b8fab3aaff7..295eae0a88e 100644
--- a/doc/development/migration_style_guide.md
+++ b/doc/development/migration_style_guide.md
@@ -111,6 +111,28 @@ class MyMigration < ActiveRecord::Migration
 end
 ```
 
+
+## Integer column type
+
+By default, an integer column can hold up to a 4-byte (32-bit) number. That is
+a max value of 2,147,483,647. Be aware of this when creating a column that will
+hold file sizes in byte units. If you are tracking file size in bytes this
+restricts the maximum file size to just over 2GB.
+
+To allow an integer column to hold up to an 8-byte (64-bit) number, explicitly
+set the limit to 8-bytes. This will allow the column to hold a value up to
+9,223,372,036,854,775,807.
+
+Rails migration example:
+
+```
+add_column_with_default(:projects, :foo, :integer, default: 10, limit: 8)
+
+# or
+
+add_column(:projects, :foo, :integer, default: 10, limit: 8)
+```
+
 ## Testing
 
 Make sure that your migration works with MySQL and PostgreSQL with data. An empty database does not guarantee that your migration is correct.