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author | Grzegorz Bizon <grzesiek.bizon@gmail.com> | 2017-07-07 10:54:13 +0200 |
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committer | Grzegorz Bizon <grzesiek.bizon@gmail.com> | 2017-07-07 15:08:15 +0200 |
commit | 84265775e56e2203199ff4d841d04b2213e97234 (patch) | |
tree | 71c0a49a8637c5a9c7dd2dcff2a9641f0471f56c | |
parent | fb89ba24825853ca29b804a4a08f7c83210f09db (diff) | |
download | gitlab-ce-84265775e56e2203199ff4d841d04b2213e97234.tar.gz |
Add some comments on new migrations helpers
-rw-r--r-- | lib/gitlab/database/migration_helpers.rb | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/lib/gitlab/database/migration_helpers.rb b/lib/gitlab/database/migration_helpers.rb index b6883704da0..ca7e4c8aa7c 100644 --- a/lib/gitlab/database/migration_helpers.rb +++ b/lib/gitlab/database/migration_helpers.rb @@ -255,6 +255,25 @@ module Gitlab end end + ## + # Iterates a table and executes a block for given range. + # + # Yields batch index, start and stop ids. + # + # Optional `scope` keyword argument is a closure that is meant to limit + # the scope the statement is going to be applied onto. + # + # Arel statement this helper will execute must be defined inside the + # block. + # + # Example: + # + # scope = ->(table, query) { query.where(table[:id].gt(100) } + # + # walk_table_in_batches(:table, of: 10, scope: scope) do |index, start, stop| + # # do something here + # end + # def walk_table_in_batches(table, of: 1000, scope: nil) if transaction_open? raise <<-MSG @@ -287,6 +306,25 @@ module Gitlab end end + ## + # Executes an SQL statement in batches, created by Arel manager. + # + # Optional `scope` keyword argument is a closure that is meant to limit + # the scope the statement is going to be applied onto. + # + # Arel statement this helper will execute must be defined inside the + # block. + # + # Example: + # + # scope = ->(table, query) { query.where(table[:id].gt(100) } + # + # execute_in_batches(:table, of: 10000, scope: scope) do |table| + # Arel::UpdateManager.new(ActiveRecord::Base) + # .table(table) + # .set([[table[:field], 101]]) + # end + # def execute_in_batches(table, of: 1000, scope: nil) if transaction_open? raise <<-MSG |