From 42e8bef3ebdcb4c1361e9fc91ec32f1bebcb6773 Mon Sep 17 00:00:00 2001 From: Evan Read Date: Tue, 27 Aug 2019 11:31:43 +0000 Subject: [PATCH] Removes trailing whitespace to fix linting --- doc/development/migration_style_guide.md | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/doc/development/migration_style_guide.md b/doc/development/migration_style_guide.md index 077dd2f43d0..4740cf4de7b 100644 --- a/doc/development/migration_style_guide.md +++ b/doc/development/migration_style_guide.md @@ -95,9 +95,9 @@ none of the steps will be executed, leaving the database in valid state. Therefore, either: - Put all migrations in one single-transaction migration. -- If necessary, put most actions in one migration and create a separate migration +- If necessary, put most actions in one migration and create a separate migration for the steps that cannot be done in a single transaction. - + For example, if you create an empty table and need to build an index for it, it is recommended to use a regular single-transaction migration and the default rails schema statement: [`add_index`](https://api.rubyonrails.org/v5.2/classes/ActiveRecord/ConnectionAdapters/SchemaStatements.html#method-i-add_index). @@ -192,9 +192,9 @@ always _first_ add a migration that removes any duplicates, before adding the unique index. When adding an index to a non-empty table make sure to use the method -`add_concurrent_index` instead of the regular `add_index` method. +`add_concurrent_index` instead of the regular `add_index` method. The `add_concurrent_index` method automatically creates concurrent indexes -when using PostgreSQL, removing the need for downtime. +when using PostgreSQL, removing the need for downtime. To use this method, you must disable single-transactions mode by calling the method `disable_ddl_transaction!` in the body of your migration @@ -216,7 +216,7 @@ class MyMigration < ActiveRecord::Migration[4.2] end ``` -For a small table (such as an empty one or one with less than `1,000` records), +For a small table (such as an empty one or one with less than `1,000` records), it is recommended to use `add_index` in a single-transaction migration, combining it with other operations that don't require `disable_ddl_transaction!`.