Commit 16674d9b authored by Nick Thomas's avatar Nick Thomas

Fix a badly-performing migration

parent 5f4ab1cd
class FixProjectRecordsWithInvalidVisibility < ActiveRecord::Migration
include Gitlab::Database::MigrationHelpers
BATCH_SIZE = 1000
BATCH_SIZE = 500
DOWNTIME = false
# This migration is idempotent and there's no sense in throwing away the
......@@ -12,34 +12,34 @@ class FixProjectRecordsWithInvalidVisibility < ActiveRecord::Migration
projects = Arel::Table.new(:projects)
namespaces = Arel::Table.new(:namespaces)
finder =
finder_sql =
projects.
join(namespaces, Arel::Nodes::InnerJoin).
on(projects[:namespace_id].eq(namespaces[:id])).
where(projects[:visibility_level].gt(namespaces[:visibility_level])).
project(projects[:id]).
take(BATCH_SIZE)
project(projects[:id], namespaces[:visibility_level]).
take(BATCH_SIZE).
to_sql
# MySQL requires a derived table to perform this query
nested_finder =
projects.
from(finder.as("AS projects_inner")).
project(projects[:id])
valuer =
namespaces.
where(namespaces[:id].eq(projects[:namespace_id])).
project(namespaces[:visibility_level])
# Update matching rows until none remain. The finder contains a limit.
# Update matching rows in batches. Each batch can cause up to 3 UPDATE
# statements, in addition to the SELECT: one per visibility_level
loop do
updater = Arel::UpdateManager.new(ActiveRecord::Base).
table(projects).
set(projects[:visibility_level] => Arel::Nodes::SqlLiteral.new("(#{valuer.to_sql})")).
where(projects[:id].in(nested_finder))
num_updated = connection.exec_update(updater.to_sql, self.class.name, [])
break if num_updated == 0
to_update = connection.exec_query(finder_sql)
break if to_update.rows.count == 0
# row[0] is projects.id, row[1] is namespaces.visibility_level
updates = to_update.rows.each_with_object(Hash.new {|h, k| h[k] = [] }) do |row, obj|
obj[row[1]] << row[0]
end
updates.each do |visibility_level, project_ids|
updater = Arel::UpdateManager.new(ActiveRecord::Base).
table(projects).
set(projects[:visibility_level] => visibility_level).
where(projects[:id].in(project_ids))
ActiveRecord::Base.connection.exec_update(updater.to_sql, self.class.name, [])
end
end
end
......
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