gitlab-org--gitlab-foss/lib/gitlab/database/migration_helpers.rb
Yorick Peterse 0054d3838c
Reduce UPDATEs for background column type changes
Prior to this commit we would essentially update all rows in a table,
even those where the source column (e.g. `issues.closed_at`) was NULL.
This in turn could lead to statement timeouts when using the default
batch size of 10 000 rows per job.

To work around this we don't schedule jobs for rows where the source
value is NULL. We also don't update rows where the source column is NULL
(as an extra precaution) or the target column already has a non-NULL
value. Using this approach it should be possible to update 10 000 rows
in the "issues" table in about 7.5 - 8 seconds.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/42158
2018-01-18 14:22:41 +01:00

864 lines
32 KiB
Ruby

module Gitlab
module Database
module MigrationHelpers
BACKGROUND_MIGRATION_BATCH_SIZE = 1000 # Number of rows to process per job
BACKGROUND_MIGRATION_JOB_BUFFER_SIZE = 1000 # Number of jobs to bulk queue at a time
# Adds `created_at` and `updated_at` columns with timezone information.
#
# This method is an improved version of Rails' built-in method `add_timestamps`.
#
# Available options are:
# default - The default value for the column.
# null - When set to `true` the column will allow NULL values.
# The default is to not allow NULL values.
def add_timestamps_with_timezone(table_name, options = {})
options[:null] = false if options[:null].nil?
[:created_at, :updated_at].each do |column_name|
if options[:default] && transaction_open?
raise '`add_timestamps_with_timezone` with default value cannot be run inside a transaction. ' \
'You can disable transactions by calling `disable_ddl_transaction!` ' \
'in the body of your migration class'
end
# If default value is presented, use `add_column_with_default` method instead.
if options[:default]
add_column_with_default(
table_name,
column_name,
:datetime_with_timezone,
default: options[:default],
allow_null: options[:null]
)
else
add_column(table_name, column_name, :datetime_with_timezone, options)
end
end
end
# Creates a new index, concurrently when supported
#
# On PostgreSQL this method creates an index concurrently, on MySQL this
# creates a regular index.
#
# Example:
#
# add_concurrent_index :users, :some_column
#
# See Rails' `add_index` for more info on the available arguments.
def add_concurrent_index(table_name, column_name, options = {})
if transaction_open?
raise 'add_concurrent_index can not be run inside a transaction, ' \
'you can disable transactions by calling disable_ddl_transaction! ' \
'in the body of your migration class'
end
if Database.postgresql?
options = options.merge({ algorithm: :concurrently })
disable_statement_timeout
end
add_index(table_name, column_name, options)
end
# Removes an existed index, concurrently when supported
#
# On PostgreSQL this method removes an index concurrently.
#
# Example:
#
# remove_concurrent_index :users, :some_column
#
# See Rails' `remove_index` for more info on the available arguments.
def remove_concurrent_index(table_name, column_name, options = {})
if transaction_open?
raise 'remove_concurrent_index can not be run inside a transaction, ' \
'you can disable transactions by calling disable_ddl_transaction! ' \
'in the body of your migration class'
end
if supports_drop_index_concurrently?
options = options.merge({ algorithm: :concurrently })
disable_statement_timeout
end
remove_index(table_name, options.merge({ column: column_name }))
end
# Removes an existing index, concurrently when supported
#
# On PostgreSQL this method removes an index concurrently.
#
# Example:
#
# remove_concurrent_index :users, "index_X_by_Y"
#
# See Rails' `remove_index` for more info on the available arguments.
def remove_concurrent_index_by_name(table_name, index_name, options = {})
if transaction_open?
raise 'remove_concurrent_index_by_name can not be run inside a transaction, ' \
'you can disable transactions by calling disable_ddl_transaction! ' \
'in the body of your migration class'
end
if supports_drop_index_concurrently?
options = options.merge({ algorithm: :concurrently })
disable_statement_timeout
end
remove_index(table_name, options.merge({ name: index_name }))
end
# Only available on Postgresql >= 9.2
def supports_drop_index_concurrently?
return false unless Database.postgresql?
version = select_one("SELECT current_setting('server_version_num') AS v")['v'].to_i
version >= 90200
end
# Adds a foreign key with only minimal locking on the tables involved.
#
# This method only requires minimal locking when using PostgreSQL. When
# using MySQL this method will use Rails' default `add_foreign_key`.
#
# source - The source table containing the foreign key.
# target - The target table the key points to.
# column - The name of the column to create the foreign key on.
# on_delete - The action to perform when associated data is removed,
# defaults to "CASCADE".
def add_concurrent_foreign_key(source, target, column:, on_delete: :cascade)
# Transactions would result in ALTER TABLE locks being held for the
# duration of the transaction, defeating the purpose of this method.
if transaction_open?
raise 'add_concurrent_foreign_key can not be run inside a transaction'
end
# While MySQL does allow disabling of foreign keys it has no equivalent
# of PostgreSQL's "VALIDATE CONSTRAINT". As a result we'll just fall
# back to the normal foreign key procedure.
if Database.mysql?
return add_foreign_key(source, target,
column: column,
on_delete: on_delete)
else
on_delete = 'SET NULL' if on_delete == :nullify
end
disable_statement_timeout
key_name = concurrent_foreign_key_name(source, column)
# Using NOT VALID allows us to create a key without immediately
# validating it. This means we keep the ALTER TABLE lock only for a
# short period of time. The key _is_ enforced for any newly created
# data.
execute <<-EOF.strip_heredoc
ALTER TABLE #{source}
ADD CONSTRAINT #{key_name}
FOREIGN KEY (#{column})
REFERENCES #{target} (id)
#{on_delete ? "ON DELETE #{on_delete.upcase}" : ''}
NOT VALID;
EOF
# Validate the existing constraint. This can potentially take a very
# long time to complete, but fortunately does not lock the source table
# while running.
execute("ALTER TABLE #{source} VALIDATE CONSTRAINT #{key_name};")
end
# Returns the name for a concurrent foreign key.
#
# PostgreSQL constraint names have a limit of 63 bytes. The logic used
# here is based on Rails' foreign_key_name() method, which unfortunately
# is private so we can't rely on it directly.
def concurrent_foreign_key_name(table, column)
"fk_#{Digest::SHA256.hexdigest("#{table}_#{column}_fk").first(10)}"
end
# Long-running migrations may take more than the timeout allowed by
# the database. Disable the session's statement timeout to ensure
# migrations don't get killed prematurely. (PostgreSQL only)
def disable_statement_timeout
execute('SET statement_timeout TO 0') if Database.postgresql?
end
def true_value
Database.true_value
end
def false_value
Database.false_value
end
# Updates the value of a column in batches.
#
# This method updates the table in batches of 5% of the total row count.
# This method will continue updating rows until no rows remain.
#
# When given a block this method will yield two values to the block:
#
# 1. An instance of `Arel::Table` for the table that is being updated.
# 2. The query to run as an Arel object.
#
# By supplying a block one can add extra conditions to the queries being
# executed. Note that the same block is used for _all_ queries.
#
# Example:
#
# update_column_in_batches(:projects, :foo, 10) do |table, query|
# query.where(table[:some_column].eq('hello'))
# end
#
# This would result in this method updating only rows where
# `projects.some_column` equals "hello".
#
# table - The name of the table.
# column - The name of the column to update.
# value - The value for the column.
#
# The `value` argument is typically a literal. To perform a computed
# update, an Arel literal can be used instead:
#
# update_value = Arel.sql('bar * baz')
#
# update_column_in_batches(:projects, :foo, update_value) do |table, query|
# query.where(table[:some_column].eq('hello'))
# end
#
# Rubocop's Metrics/AbcSize metric is disabled for this method as Rubocop
# determines this method to be too complex while there's no way to make it
# less "complex" without introducing extra methods (which actually will
# make things _more_ complex).
#
# rubocop: disable Metrics/AbcSize
def update_column_in_batches(table, column, value)
if transaction_open?
raise 'update_column_in_batches can not be run inside a transaction, ' \
'you can disable transactions by calling disable_ddl_transaction! ' \
'in the body of your migration class'
end
table = Arel::Table.new(table)
count_arel = table.project(Arel.star.count.as('count'))
count_arel = yield table, count_arel if block_given?
total = exec_query(count_arel.to_sql).to_hash.first['count'].to_i
return if total == 0
# Update in batches of 5% until we run out of any rows to update.
batch_size = ((total / 100.0) * 5.0).ceil
max_size = 1000
# The upper limit is 1000 to ensure we don't lock too many rows. For
# example, for "merge_requests" even 1% of the table is around 35 000
# rows for GitLab.com.
batch_size = max_size if batch_size > max_size
start_arel = table.project(table[:id]).order(table[:id].asc).take(1)
start_arel = yield table, start_arel if block_given?
start_id = exec_query(start_arel.to_sql).to_hash.first['id'].to_i
loop do
stop_arel = table.project(table[:id])
.where(table[:id].gteq(start_id))
.order(table[:id].asc)
.take(1)
.skip(batch_size)
stop_arel = yield table, stop_arel if block_given?
stop_row = exec_query(stop_arel.to_sql).to_hash.first
update_arel = Arel::UpdateManager.new(ActiveRecord::Base)
.table(table)
.set([[table[column], value]])
.where(table[:id].gteq(start_id))
if stop_row
stop_id = stop_row['id'].to_i
start_id = stop_id
update_arel = update_arel.where(table[:id].lt(stop_id))
end
update_arel = yield table, update_arel if block_given?
execute(update_arel.to_sql)
# There are no more rows left to update.
break unless stop_row
end
end
# Adds a column with a default value without locking an entire table.
#
# This method runs the following steps:
#
# 1. Add the column with a default value of NULL.
# 2. Change the default value of the column to the specified value.
# 3. Update all existing rows in batches.
# 4. Set a `NOT NULL` constraint on the column if desired (the default).
#
# These steps ensure a column can be added to a large and commonly used
# table without locking the entire table for the duration of the table
# modification.
#
# table - The name of the table to update.
# column - The name of the column to add.
# type - The column type (e.g. `:integer`).
# default - The default value for the column.
# limit - Sets a column limit. For example, for :integer, the default is
# 4-bytes. Set `limit: 8` to allow 8-byte integers.
# allow_null - When set to `true` the column will allow NULL values, the
# default is to not allow NULL values.
#
# This method can also take a block which is passed directly to the
# `update_column_in_batches` method.
def add_column_with_default(table, column, type, default:, limit: nil, allow_null: false, &block)
if transaction_open?
raise 'add_column_with_default can not be run inside a transaction, ' \
'you can disable transactions by calling disable_ddl_transaction! ' \
'in the body of your migration class'
end
disable_statement_timeout
transaction do
if limit
add_column(table, column, type, default: nil, limit: limit)
else
add_column(table, column, type, default: nil)
end
# Changing the default before the update ensures any newly inserted
# rows already use the proper default value.
change_column_default(table, column, default)
end
begin
update_column_in_batches(table, column, default, &block)
change_column_null(table, column, false) unless allow_null
# We want to rescue _all_ exceptions here, even those that don't inherit
# from StandardError.
rescue Exception => error # rubocop: disable all
remove_column(table, column)
raise error
end
end
# Renames a column without requiring downtime.
#
# Concurrent renames work by using database triggers to ensure both the
# old and new column are in sync. However, this method will _not_ remove
# the triggers or the old column automatically; this needs to be done
# manually in a post-deployment migration. This can be done using the
# method `cleanup_concurrent_column_rename`.
#
# table - The name of the database table containing the column.
# old - The old column name.
# new - The new column name.
# type - The type of the new column. If no type is given the old column's
# type is used.
def rename_column_concurrently(table, old, new, type: nil)
if transaction_open?
raise 'rename_column_concurrently can not be run inside a transaction'
end
check_trigger_permissions!(table)
old_col = column_for(table, old)
new_type = type || old_col.type
add_column(table, new, new_type,
limit: old_col.limit,
precision: old_col.precision,
scale: old_col.scale)
# We set the default value _after_ adding the column so we don't end up
# updating any existing data with the default value. This isn't
# necessary since we copy over old values further down.
change_column_default(table, new, old_col.default) if old_col.default
install_rename_triggers(table, old, new)
update_column_in_batches(table, new, Arel::Table.new(table)[old])
change_column_null(table, new, false) unless old_col.null
copy_indexes(table, old, new)
copy_foreign_keys(table, old, new)
end
# Installs triggers in a table that keep a new column in sync with an old
# one.
#
# table - The name of the table to install the trigger in.
# old_column - The name of the old column.
# new_column - The name of the new column.
def install_rename_triggers(table, old_column, new_column)
trigger_name = rename_trigger_name(table, old_column, new_column)
quoted_table = quote_table_name(table)
quoted_old = quote_column_name(old_column)
quoted_new = quote_column_name(new_column)
if Database.postgresql?
install_rename_triggers_for_postgresql(trigger_name, quoted_table,
quoted_old, quoted_new)
else
install_rename_triggers_for_mysql(trigger_name, quoted_table,
quoted_old, quoted_new)
end
end
# Changes the type of a column concurrently.
#
# table - The table containing the column.
# column - The name of the column to change.
# new_type - The new column type.
def change_column_type_concurrently(table, column, new_type)
temp_column = "#{column}_for_type_change"
rename_column_concurrently(table, column, temp_column, type: new_type)
end
# Performs cleanup of a concurrent type change.
#
# table - The table containing the column.
# column - The name of the column to change.
# new_type - The new column type.
def cleanup_concurrent_column_type_change(table, column)
temp_column = "#{column}_for_type_change"
transaction do
# This has to be performed in a transaction as otherwise we might have
# inconsistent data.
cleanup_concurrent_column_rename(table, column, temp_column)
rename_column(table, temp_column, column)
end
end
# Cleans up a concurrent column name.
#
# This method takes care of removing previously installed triggers as well
# as removing the old column.
#
# table - The name of the database table.
# old - The name of the old column.
# new - The name of the new column.
def cleanup_concurrent_column_rename(table, old, new)
trigger_name = rename_trigger_name(table, old, new)
check_trigger_permissions!(table)
if Database.postgresql?
remove_rename_triggers_for_postgresql(table, trigger_name)
else
remove_rename_triggers_for_mysql(trigger_name)
end
remove_column(table, old)
end
# Changes the column type of a table using a background migration.
#
# Because this method uses a background migration it's more suitable for
# large tables. For small tables it's better to use
# `change_column_type_concurrently` since it can complete its work in a
# much shorter amount of time and doesn't rely on Sidekiq.
#
# Example usage:
#
# class Issue < ActiveRecord::Base
# self.table_name = 'issues'
#
# include EachBatch
#
# def self.to_migrate
# where('closed_at IS NOT NULL')
# end
# end
#
# change_column_type_using_background_migration(
# Issue.to_migrate,
# :closed_at,
# :datetime_with_timezone
# )
#
# Reverting a migration like this is done exactly the same way, just with
# a different type to migrate to (e.g. `:datetime` in the above example).
#
# relation - An ActiveRecord relation to use for scheduling jobs and
# figuring out what table we're modifying. This relation _must_
# have the EachBatch module included.
#
# column - The name of the column for which the type will be changed.
#
# new_type - The new type of the column.
#
# batch_size - The number of rows to schedule in a single background
# migration.
#
# interval - The time interval between every background migration.
def change_column_type_using_background_migration(
relation,
column,
new_type,
batch_size: 10_000,
interval: 10.minutes
)
unless relation.model < EachBatch
raise TypeError, 'The relation must include the EachBatch module'
end
temp_column = "#{column}_for_type_change"
table = relation.table_name
max_index = 0
add_column(table, temp_column, new_type)
install_rename_triggers(table, column, temp_column)
# Schedule the jobs that will copy the data from the old column to the
# new one. Rows with NULL values in our source column are skipped since
# the target column is already NULL at this point.
relation.where.not(column => nil).each_batch(of: batch_size) do |batch, index|
start_id, end_id = batch.pluck('MIN(id), MAX(id)').first
max_index = index
BackgroundMigrationWorker.perform_in(
index * interval,
'CopyColumn',
[table, column, temp_column, start_id, end_id]
)
end
# Schedule the renaming of the column to happen (initially) 1 hour after
# the last batch finished.
BackgroundMigrationWorker.perform_in(
(max_index * interval) + 1.hour,
'CleanupConcurrentTypeChange',
[table, column, temp_column]
)
if perform_background_migration_inline?
# To ensure the schema is up to date immediately we perform the
# migration inline in dev / test environments.
Gitlab::BackgroundMigration.steal('CopyColumn')
Gitlab::BackgroundMigration.steal('CleanupConcurrentTypeChange')
end
end
def perform_background_migration_inline?
Rails.env.test? || Rails.env.development?
end
# Performs a concurrent column rename when using PostgreSQL.
def install_rename_triggers_for_postgresql(trigger, table, old, new)
execute <<-EOF.strip_heredoc
CREATE OR REPLACE FUNCTION #{trigger}()
RETURNS trigger AS
$BODY$
BEGIN
NEW.#{new} := NEW.#{old};
RETURN NEW;
END;
$BODY$
LANGUAGE 'plpgsql'
VOLATILE
EOF
execute <<-EOF.strip_heredoc
CREATE TRIGGER #{trigger}
BEFORE INSERT OR UPDATE
ON #{table}
FOR EACH ROW
EXECUTE PROCEDURE #{trigger}()
EOF
end
# Installs the triggers necessary to perform a concurrent column rename on
# MySQL.
def install_rename_triggers_for_mysql(trigger, table, old, new)
execute <<-EOF.strip_heredoc
CREATE TRIGGER #{trigger}_insert
BEFORE INSERT
ON #{table}
FOR EACH ROW
SET NEW.#{new} = NEW.#{old}
EOF
execute <<-EOF.strip_heredoc
CREATE TRIGGER #{trigger}_update
BEFORE UPDATE
ON #{table}
FOR EACH ROW
SET NEW.#{new} = NEW.#{old}
EOF
end
# Removes the triggers used for renaming a PostgreSQL column concurrently.
def remove_rename_triggers_for_postgresql(table, trigger)
execute("DROP TRIGGER IF EXISTS #{trigger} ON #{table}")
execute("DROP FUNCTION IF EXISTS #{trigger}()")
end
# Removes the triggers used for renaming a MySQL column concurrently.
def remove_rename_triggers_for_mysql(trigger)
execute("DROP TRIGGER IF EXISTS #{trigger}_insert")
execute("DROP TRIGGER IF EXISTS #{trigger}_update")
end
# Returns the (base) name to use for triggers when renaming columns.
def rename_trigger_name(table, old, new)
'trigger_' + Digest::SHA256.hexdigest("#{table}_#{old}_#{new}").first(12)
end
# Returns an Array containing the indexes for the given column
def indexes_for(table, column)
column = column.to_s
indexes(table).select { |index| index.columns.include?(column) }
end
# Returns an Array containing the foreign keys for the given column.
def foreign_keys_for(table, column)
column = column.to_s
foreign_keys(table).select { |fk| fk.column == column }
end
# Copies all indexes for the old column to a new column.
#
# table - The table containing the columns and indexes.
# old - The old column.
# new - The new column.
def copy_indexes(table, old, new)
old = old.to_s
new = new.to_s
indexes_for(table, old).each do |index|
new_columns = index.columns.map do |column|
column == old ? new : column
end
# This is necessary as we can't properly rename indexes such as
# "ci_taggings_idx".
unless index.name.include?(old)
raise "The index #{index.name} can not be copied as it does not "\
"mention the old column. You have to rename this index manually first."
end
name = index.name.gsub(old, new)
options = {
unique: index.unique,
name: name,
length: index.lengths,
order: index.orders
}
# These options are not supported by MySQL, so we only add them if
# they were previously set.
options[:using] = index.using if index.using
options[:where] = index.where if index.where
unless index.opclasses.blank?
opclasses = index.opclasses.dup
# Copy the operator classes for the old column (if any) to the new
# column.
opclasses[new] = opclasses.delete(old) if opclasses[old]
options[:opclasses] = opclasses
end
add_concurrent_index(table, new_columns, options)
end
end
# Copies all foreign keys for the old column to the new column.
#
# table - The table containing the columns and indexes.
# old - The old column.
# new - The new column.
def copy_foreign_keys(table, old, new)
foreign_keys_for(table, old).each do |fk|
add_concurrent_foreign_key(fk.from_table,
fk.to_table,
column: new,
on_delete: fk.on_delete)
end
end
# Returns the column for the given table and column name.
def column_for(table, name)
name = name.to_s
columns(table).find { |column| column.name == name }
end
# This will replace the first occurance of a string in a column with
# the replacement
# On postgresql we can use `regexp_replace` for that.
# On mysql we find the location of the pattern, and overwrite it
# with the replacement
def replace_sql(column, pattern, replacement)
quoted_pattern = Arel::Nodes::Quoted.new(pattern.to_s)
quoted_replacement = Arel::Nodes::Quoted.new(replacement.to_s)
if Database.mysql?
locate = Arel::Nodes::NamedFunction
.new('locate', [quoted_pattern, column])
insert_in_place = Arel::Nodes::NamedFunction
.new('insert', [column, locate, pattern.size, quoted_replacement])
Arel::Nodes::SqlLiteral.new(insert_in_place.to_sql)
else
replace = Arel::Nodes::NamedFunction
.new("regexp_replace", [column, quoted_pattern, quoted_replacement])
Arel::Nodes::SqlLiteral.new(replace.to_sql)
end
end
def remove_foreign_key_without_error(*args)
remove_foreign_key(*args)
rescue ArgumentError
end
def sidekiq_queue_migrate(queue_from, to:)
while sidekiq_queue_length(queue_from) > 0
Sidekiq.redis do |conn|
conn.rpoplpush "queue:#{queue_from}", "queue:#{to}"
end
end
end
def sidekiq_queue_length(queue_name)
Sidekiq.redis do |conn|
conn.llen("queue:#{queue_name}")
end
end
def check_trigger_permissions!(table)
unless Grant.create_and_execute_trigger?(table)
dbname = Database.database_name
user = Database.username
raise <<-EOF
Your database user is not allowed to create, drop, or execute triggers on the
table #{table}.
If you are using PostgreSQL you can solve this by logging in to the GitLab
database (#{dbname}) using a super user and running:
ALTER #{user} WITH SUPERUSER
For MySQL you instead need to run:
GRANT ALL PRIVILEGES ON *.* TO #{user}@'%'
Both queries will grant the user super user permissions, ensuring you don't run
into similar problems in the future (e.g. when new tables are created).
EOF
end
end
# Bulk queues background migration jobs for an entire table, batched by ID range.
# "Bulk" meaning many jobs will be pushed at a time for efficiency.
# If you need a delay interval per job, then use `queue_background_migration_jobs_by_range_at_intervals`.
#
# model_class - The table being iterated over
# job_class_name - The background migration job class as a string
# batch_size - The maximum number of rows per job
#
# Example:
#
# class Route < ActiveRecord::Base
# include EachBatch
# self.table_name = 'routes'
# end
#
# bulk_queue_background_migration_jobs_by_range(Route, 'ProcessRoutes')
#
# Where the model_class includes EachBatch, and the background migration exists:
#
# class Gitlab::BackgroundMigration::ProcessRoutes
# def perform(start_id, end_id)
# # do something
# end
# end
def bulk_queue_background_migration_jobs_by_range(model_class, job_class_name, batch_size: BACKGROUND_MIGRATION_BATCH_SIZE)
raise "#{model_class} does not have an ID to use for batch ranges" unless model_class.column_names.include?('id')
jobs = []
model_class.each_batch(of: batch_size) do |relation|
start_id, end_id = relation.pluck('MIN(id), MAX(id)').first
if jobs.length >= BACKGROUND_MIGRATION_JOB_BUFFER_SIZE
# Note: This code path generally only helps with many millions of rows
# We push multiple jobs at a time to reduce the time spent in
# Sidekiq/Redis operations. We're using this buffer based approach so we
# don't need to run additional queries for every range.
BackgroundMigrationWorker.bulk_perform_async(jobs)
jobs.clear
end
jobs << [job_class_name, [start_id, end_id]]
end
BackgroundMigrationWorker.bulk_perform_async(jobs) unless jobs.empty?
end
# Queues background migration jobs for an entire table, batched by ID range.
# Each job is scheduled with a `delay_interval` in between.
# If you use a small interval, then some jobs may run at the same time.
#
# model_class - The table being iterated over
# job_class_name - The background migration job class as a string
# delay_interval - The duration between each job's scheduled time (must respond to `to_f`)
# batch_size - The maximum number of rows per job
#
# Example:
#
# class Route < ActiveRecord::Base
# include EachBatch
# self.table_name = 'routes'
# end
#
# queue_background_migration_jobs_by_range_at_intervals(Route, 'ProcessRoutes', 1.minute)
#
# Where the model_class includes EachBatch, and the background migration exists:
#
# class Gitlab::BackgroundMigration::ProcessRoutes
# def perform(start_id, end_id)
# # do something
# end
# end
def queue_background_migration_jobs_by_range_at_intervals(model_class, job_class_name, delay_interval, batch_size: BACKGROUND_MIGRATION_BATCH_SIZE)
raise "#{model_class} does not have an ID to use for batch ranges" unless model_class.column_names.include?('id')
# To not overload the worker too much we enforce a minimum interval both
# when scheduling and performing jobs.
if delay_interval < BackgroundMigrationWorker::MIN_INTERVAL
delay_interval = BackgroundMigrationWorker::MIN_INTERVAL
end
model_class.each_batch(of: batch_size) do |relation, index|
start_id, end_id = relation.pluck('MIN(id), MAX(id)').first
# `BackgroundMigrationWorker.bulk_perform_in` schedules all jobs for
# the same time, which is not helpful in most cases where we wish to
# spread the work over time.
BackgroundMigrationWorker.perform_in(delay_interval * index, job_class_name, [start_id, end_id])
end
end
end
end
end