616 lines
22 KiB
Ruby
616 lines
22 KiB
Ruby
module Gitlab
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module Database
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module MigrationHelpers
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# Adds `created_at` and `updated_at` columns with timezone information.
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#
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# This method is an improved version of Rails' built-in method `add_timestamps`.
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#
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# Available options are:
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# default - The default value for the column.
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# null - When set to `true` the column will allow NULL values.
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# The default is to not allow NULL values.
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def add_timestamps_with_timezone(table_name, options = {})
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options[:null] = false if options[:null].nil?
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[:created_at, :updated_at].each do |column_name|
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if options[:default] && transaction_open?
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raise '`add_timestamps_with_timezone` with default value cannot be run inside a transaction. ' \
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'You can disable transactions by calling `disable_ddl_transaction!` ' \
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'in the body of your migration class'
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end
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# If default value is presented, use `add_column_with_default` method instead.
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if options[:default]
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add_column_with_default(
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table_name,
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column_name,
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:datetime_with_timezone,
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default: options[:default],
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allow_null: options[:null]
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)
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else
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add_column(table_name, column_name, :datetime_with_timezone, options)
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end
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end
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end
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# Creates a new index, concurrently when supported
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#
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# On PostgreSQL this method creates an index concurrently, on MySQL this
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# creates a regular index.
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#
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# Example:
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#
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# add_concurrent_index :users, :some_column
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#
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# See Rails' `add_index` for more info on the available arguments.
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def add_concurrent_index(table_name, column_name, options = {})
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if transaction_open?
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raise 'add_concurrent_index can not be run inside a transaction, ' \
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'you can disable transactions by calling disable_ddl_transaction! ' \
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'in the body of your migration class'
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end
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if Database.postgresql?
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options = options.merge({ algorithm: :concurrently })
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disable_statement_timeout
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end
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add_index(table_name, column_name, options)
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end
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# Removes an existed index, concurrently when supported
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#
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# On PostgreSQL this method removes an index concurrently.
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#
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# Example:
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#
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# remove_concurrent_index :users, :some_column
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#
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# See Rails' `remove_index` for more info on the available arguments.
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def remove_concurrent_index(table_name, column_name, options = {})
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if transaction_open?
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raise 'remove_concurrent_index can not be run inside a transaction, ' \
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'you can disable transactions by calling disable_ddl_transaction! ' \
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'in the body of your migration class'
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end
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if supports_drop_index_concurrently?
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options = options.merge({ algorithm: :concurrently })
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disable_statement_timeout
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end
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remove_index(table_name, options.merge({ column: column_name }))
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end
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# Removes an existing index, concurrently when supported
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#
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# On PostgreSQL this method removes an index concurrently.
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#
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# Example:
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#
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# remove_concurrent_index :users, "index_X_by_Y"
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#
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# See Rails' `remove_index` for more info on the available arguments.
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def remove_concurrent_index_by_name(table_name, index_name, options = {})
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if transaction_open?
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raise 'remove_concurrent_index_by_name can not be run inside a transaction, ' \
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'you can disable transactions by calling disable_ddl_transaction! ' \
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'in the body of your migration class'
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end
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if supports_drop_index_concurrently?
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options = options.merge({ algorithm: :concurrently })
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disable_statement_timeout
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end
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remove_index(table_name, options.merge({ name: index_name }))
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end
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# Only available on Postgresql >= 9.2
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def supports_drop_index_concurrently?
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return false unless Database.postgresql?
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version = select_one("SELECT current_setting('server_version_num') AS v")['v'].to_i
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version >= 90200
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end
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# Adds a foreign key with only minimal locking on the tables involved.
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#
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# This method only requires minimal locking when using PostgreSQL. When
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# using MySQL this method will use Rails' default `add_foreign_key`.
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#
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# source - The source table containing the foreign key.
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# target - The target table the key points to.
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# column - The name of the column to create the foreign key on.
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# on_delete - The action to perform when associated data is removed,
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# defaults to "CASCADE".
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def add_concurrent_foreign_key(source, target, column:, on_delete: :cascade)
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# Transactions would result in ALTER TABLE locks being held for the
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# duration of the transaction, defeating the purpose of this method.
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if transaction_open?
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raise 'add_concurrent_foreign_key can not be run inside a transaction'
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end
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# While MySQL does allow disabling of foreign keys it has no equivalent
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# of PostgreSQL's "VALIDATE CONSTRAINT". As a result we'll just fall
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# back to the normal foreign key procedure.
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if Database.mysql?
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return add_foreign_key(source, target,
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column: column,
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on_delete: on_delete)
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else
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on_delete = 'SET NULL' if on_delete == :nullify
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end
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disable_statement_timeout
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key_name = concurrent_foreign_key_name(source, column)
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# Using NOT VALID allows us to create a key without immediately
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# validating it. This means we keep the ALTER TABLE lock only for a
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# short period of time. The key _is_ enforced for any newly created
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# data.
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execute <<-EOF.strip_heredoc
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ALTER TABLE #{source}
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ADD CONSTRAINT #{key_name}
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FOREIGN KEY (#{column})
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REFERENCES #{target} (id)
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#{on_delete ? "ON DELETE #{on_delete.upcase}" : ''}
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NOT VALID;
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EOF
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# Validate the existing constraint. This can potentially take a very
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# long time to complete, but fortunately does not lock the source table
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# while running.
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execute("ALTER TABLE #{source} VALIDATE CONSTRAINT #{key_name};")
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end
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# Returns the name for a concurrent foreign key.
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#
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# PostgreSQL constraint names have a limit of 63 bytes. The logic used
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# here is based on Rails' foreign_key_name() method, which unfortunately
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# is private so we can't rely on it directly.
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def concurrent_foreign_key_name(table, column)
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"fk_#{Digest::SHA256.hexdigest("#{table}_#{column}_fk").first(10)}"
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end
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# Long-running migrations may take more than the timeout allowed by
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# the database. Disable the session's statement timeout to ensure
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# migrations don't get killed prematurely. (PostgreSQL only)
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def disable_statement_timeout
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execute('SET statement_timeout TO 0') if Database.postgresql?
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end
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def true_value
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Database.true_value
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end
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def false_value
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Database.false_value
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end
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# Updates the value of a column in batches.
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#
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# This method updates the table in batches of 5% of the total row count.
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# This method will continue updating rows until no rows remain.
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#
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# When given a block this method will yield two values to the block:
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#
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# 1. An instance of `Arel::Table` for the table that is being updated.
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# 2. The query to run as an Arel object.
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#
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# By supplying a block one can add extra conditions to the queries being
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# executed. Note that the same block is used for _all_ queries.
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#
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# Example:
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#
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# update_column_in_batches(:projects, :foo, 10) do |table, query|
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# query.where(table[:some_column].eq('hello'))
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# end
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#
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# This would result in this method updating only rows where
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# `projects.some_column` equals "hello".
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#
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# table - The name of the table.
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# column - The name of the column to update.
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# value - The value for the column.
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#
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# Rubocop's Metrics/AbcSize metric is disabled for this method as Rubocop
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# determines this method to be too complex while there's no way to make it
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# less "complex" without introducing extra methods (which actually will
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# make things _more_ complex).
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#
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# rubocop: disable Metrics/AbcSize
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def update_column_in_batches(table, column, value)
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if transaction_open?
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raise 'update_column_in_batches can not be run inside a transaction, ' \
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'you can disable transactions by calling disable_ddl_transaction! ' \
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'in the body of your migration class'
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end
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table = Arel::Table.new(table)
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count_arel = table.project(Arel.star.count.as('count'))
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count_arel = yield table, count_arel if block_given?
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total = exec_query(count_arel.to_sql).to_hash.first['count'].to_i
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return if total == 0
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# Update in batches of 5% until we run out of any rows to update.
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batch_size = ((total / 100.0) * 5.0).ceil
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max_size = 1000
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# The upper limit is 1000 to ensure we don't lock too many rows. For
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# example, for "merge_requests" even 1% of the table is around 35 000
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# rows for GitLab.com.
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batch_size = max_size if batch_size > max_size
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start_arel = table.project(table[:id]).order(table[:id].asc).take(1)
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start_arel = yield table, start_arel if block_given?
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start_id = exec_query(start_arel.to_sql).to_hash.first['id'].to_i
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loop do
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stop_arel = table.project(table[:id])
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.where(table[:id].gteq(start_id))
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.order(table[:id].asc)
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.take(1)
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.skip(batch_size)
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stop_arel = yield table, stop_arel if block_given?
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stop_row = exec_query(stop_arel.to_sql).to_hash.first
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update_arel = Arel::UpdateManager.new(ActiveRecord::Base)
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.table(table)
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.set([[table[column], value]])
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.where(table[:id].gteq(start_id))
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if stop_row
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stop_id = stop_row['id'].to_i
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start_id = stop_id
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update_arel = update_arel.where(table[:id].lt(stop_id))
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end
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update_arel = yield table, update_arel if block_given?
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execute(update_arel.to_sql)
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# There are no more rows left to update.
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break unless stop_row
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end
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end
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# Adds a column with a default value without locking an entire table.
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#
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# This method runs the following steps:
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#
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# 1. Add the column with a default value of NULL.
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# 2. Change the default value of the column to the specified value.
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# 3. Update all existing rows in batches.
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# 4. Set a `NOT NULL` constraint on the column if desired (the default).
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#
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# These steps ensure a column can be added to a large and commonly used
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# table without locking the entire table for the duration of the table
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# modification.
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#
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# table - The name of the table to update.
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# column - The name of the column to add.
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# type - The column type (e.g. `:integer`).
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# default - The default value for the column.
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# limit - Sets a column limit. For example, for :integer, the default is
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# 4-bytes. Set `limit: 8` to allow 8-byte integers.
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# allow_null - When set to `true` the column will allow NULL values, the
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# default is to not allow NULL values.
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#
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# This method can also take a block which is passed directly to the
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# `update_column_in_batches` method.
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def add_column_with_default(table, column, type, default:, limit: nil, allow_null: false, &block)
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if transaction_open?
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raise 'add_column_with_default can not be run inside a transaction, ' \
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'you can disable transactions by calling disable_ddl_transaction! ' \
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'in the body of your migration class'
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end
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disable_statement_timeout
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transaction do
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if limit
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add_column(table, column, type, default: nil, limit: limit)
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else
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add_column(table, column, type, default: nil)
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end
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# Changing the default before the update ensures any newly inserted
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# rows already use the proper default value.
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change_column_default(table, column, default)
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end
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begin
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update_column_in_batches(table, column, default, &block)
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change_column_null(table, column, false) unless allow_null
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# We want to rescue _all_ exceptions here, even those that don't inherit
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# from StandardError.
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rescue Exception => error # rubocop: disable all
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remove_column(table, column)
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raise error
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end
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end
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# Renames a column without requiring downtime.
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#
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# Concurrent renames work by using database triggers to ensure both the
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# old and new column are in sync. However, this method will _not_ remove
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# the triggers or the old column automatically; this needs to be done
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# manually in a post-deployment migration. This can be done using the
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# method `cleanup_concurrent_column_rename`.
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#
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# table - The name of the database table containing the column.
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# old - The old column name.
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# new - The new column name.
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# type - The type of the new column. If no type is given the old column's
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# type is used.
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def rename_column_concurrently(table, old, new, type: nil)
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if transaction_open?
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raise 'rename_column_concurrently can not be run inside a transaction'
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end
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old_col = column_for(table, old)
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new_type = type || old_col.type
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add_column(table, new, new_type,
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limit: old_col.limit,
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precision: old_col.precision,
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scale: old_col.scale)
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# We set the default value _after_ adding the column so we don't end up
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# updating any existing data with the default value. This isn't
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# necessary since we copy over old values further down.
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change_column_default(table, new, old_col.default) if old_col.default
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trigger_name = rename_trigger_name(table, old, new)
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quoted_table = quote_table_name(table)
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quoted_old = quote_column_name(old)
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quoted_new = quote_column_name(new)
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if Database.postgresql?
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install_rename_triggers_for_postgresql(trigger_name, quoted_table,
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quoted_old, quoted_new)
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else
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install_rename_triggers_for_mysql(trigger_name, quoted_table,
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quoted_old, quoted_new)
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end
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update_column_in_batches(table, new, Arel::Table.new(table)[old])
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change_column_null(table, new, false) unless old_col.null
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copy_indexes(table, old, new)
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copy_foreign_keys(table, old, new)
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end
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# Changes the type of a column concurrently.
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#
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# table - The table containing the column.
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# column - The name of the column to change.
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# new_type - The new column type.
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def change_column_type_concurrently(table, column, new_type)
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temp_column = "#{column}_for_type_change"
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rename_column_concurrently(table, column, temp_column, type: new_type)
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end
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# Performs cleanup of a concurrent type change.
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#
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# table - The table containing the column.
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# column - The name of the column to change.
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# new_type - The new column type.
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def cleanup_concurrent_column_type_change(table, column)
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temp_column = "#{column}_for_type_change"
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transaction do
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# This has to be performed in a transaction as otherwise we might have
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# inconsistent data.
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cleanup_concurrent_column_rename(table, column, temp_column)
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rename_column(table, temp_column, column)
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end
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end
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# Cleans up a concurrent column name.
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#
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# This method takes care of removing previously installed triggers as well
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# as removing the old column.
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#
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# table - The name of the database table.
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# old - The name of the old column.
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# new - The name of the new column.
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def cleanup_concurrent_column_rename(table, old, new)
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trigger_name = rename_trigger_name(table, old, new)
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if Database.postgresql?
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remove_rename_triggers_for_postgresql(table, trigger_name)
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else
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remove_rename_triggers_for_mysql(trigger_name)
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end
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remove_column(table, old)
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end
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# Performs a concurrent column rename when using PostgreSQL.
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def install_rename_triggers_for_postgresql(trigger, table, old, new)
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execute <<-EOF.strip_heredoc
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CREATE OR REPLACE FUNCTION #{trigger}()
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RETURNS trigger AS
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$BODY$
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BEGIN
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NEW.#{new} := NEW.#{old};
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RETURN NEW;
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END;
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$BODY$
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LANGUAGE 'plpgsql'
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VOLATILE
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EOF
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execute <<-EOF.strip_heredoc
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CREATE TRIGGER #{trigger}
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BEFORE INSERT OR UPDATE
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ON #{table}
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FOR EACH ROW
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EXECUTE PROCEDURE #{trigger}()
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EOF
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end
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# Installs the triggers necessary to perform a concurrent column rename on
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# MySQL.
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def install_rename_triggers_for_mysql(trigger, table, old, new)
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execute <<-EOF.strip_heredoc
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CREATE TRIGGER #{trigger}_insert
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BEFORE INSERT
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ON #{table}
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FOR EACH ROW
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SET NEW.#{new} = NEW.#{old}
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EOF
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execute <<-EOF.strip_heredoc
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CREATE TRIGGER #{trigger}_update
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BEFORE UPDATE
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ON #{table}
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FOR EACH ROW
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SET NEW.#{new} = NEW.#{old}
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EOF
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end
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# Removes the triggers used for renaming a PostgreSQL column concurrently.
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def remove_rename_triggers_for_postgresql(table, trigger)
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execute("DROP TRIGGER #{trigger} ON #{table}")
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execute("DROP FUNCTION #{trigger}()")
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end
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# Removes the triggers used for renaming a MySQL column concurrently.
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def remove_rename_triggers_for_mysql(trigger)
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execute("DROP TRIGGER #{trigger}_insert")
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execute("DROP TRIGGER #{trigger}_update")
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end
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# Returns the (base) name to use for triggers when renaming columns.
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def rename_trigger_name(table, old, new)
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'trigger_' + Digest::SHA256.hexdigest("#{table}_#{old}_#{new}").first(12)
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end
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# Returns an Array containing the indexes for the given column
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def indexes_for(table, column)
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column = column.to_s
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indexes(table).select { |index| index.columns.include?(column) }
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end
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# Returns an Array containing the foreign keys for the given column.
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def foreign_keys_for(table, column)
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column = column.to_s
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foreign_keys(table).select { |fk| fk.column == column }
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end
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# Copies all indexes for the old column to a new column.
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#
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# table - The table containing the columns and indexes.
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# old - The old column.
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# new - The new column.
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def copy_indexes(table, old, new)
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old = old.to_s
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new = new.to_s
|
|
|
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indexes_for(table, old).each do |index|
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new_columns = index.columns.map do |column|
|
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column == old ? new : column
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end
|
|
|
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# This is necessary as we can't properly rename indexes such as
|
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# "ci_taggings_idx".
|
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unless index.name.include?(old)
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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,
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|
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
|
|
end
|
|
end
|
|
end
|