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# frozen_string_literal: true
module Gitlab
module Database
module Partitioning
class ReplaceTable
DELIMITER = ";\n\n"
attr_reader :original_table, :replacement_table, :replaced_table, :primary_key_column,
:sequence, :original_primary_key, :replacement_primary_key, :replaced_primary_key
def initialize(connection, original_table, replacement_table, replaced_table, primary_key_column)
@connection = connection
@original_table = original_table
@replacement_table = replacement_table
@replaced_table = replaced_table
@primary_key_column = primary_key_column
@sequence = default_sequence(original_table, primary_key_column)
@original_primary_key = default_primary_key(original_table)
@replacement_primary_key = default_primary_key(replacement_table)
@replaced_primary_key = default_primary_key(replaced_table)
end
def perform
yield sql_to_replace_table if block_given?
execute(sql_to_replace_table)
end
private
attr_reader :connection
delegate :execute, :quote_table_name, :quote_column_name, to: :connection
def default_sequence(table, column)
"#{table}_#{column}_seq"
end
def default_primary_key(table)
"#{table}_pkey"
end
def sql_to_replace_table
@sql_to_replace_table ||= combined_sql_statements.map(&:chomp).join(DELIMITER)
end
def combined_sql_statements
statements = []
statements << alter_column_default(original_table, primary_key_column, expression: nil)
statements << alter_column_default(replacement_table, primary_key_column,
expression: "nextval('#{quote_table_name(sequence)}'::regclass)")
statements << alter_sequence_owned_by(sequence, replacement_table, primary_key_column)
rename_table_objects(statements, original_table, replaced_table, original_primary_key, replaced_primary_key)
rename_table_objects(statements, replacement_table, original_table, replacement_primary_key, original_primary_key)
statements
end
def rename_table_objects(statements, old_table, new_table, old_primary_key, new_primary_key)
statements << rename_table(old_table, new_table)
statements << rename_constraint(new_table, old_primary_key, new_primary_key)
rename_partitions(statements, old_table, new_table)
end
def rename_partitions(statements, old_table_name, new_table_name)
Gitlab::Database::PostgresPartition.for_parent_table(old_table_name).each do |partition|
new_partition_name = partition.name.sub(/#{old_table_name}/, new_table_name)
old_primary_key = default_primary_key(partition.name)
new_primary_key = default_primary_key(new_partition_name)
statements << rename_constraint(partition.identifier, old_primary_key, new_primary_key)
statements << rename_table(partition.identifier, new_partition_name)
end
end
def alter_column_default(table_name, column_name, expression:)
default_clause = expression.nil? ? 'DROP DEFAULT' : "SET DEFAULT #{expression}"
<<~SQL
ALTER TABLE #{quote_table_name(table_name)}
ALTER COLUMN #{quote_column_name(column_name)} #{default_clause}
SQL
end
def alter_sequence_owned_by(sequence_name, table_name, column_name)
<<~SQL
ALTER SEQUENCE #{quote_table_name(sequence_name)}
OWNED BY #{quote_table_name(table_name)}.#{quote_column_name(column_name)}
SQL
end
def rename_table(old_name, new_name)
<<~SQL
ALTER TABLE #{quote_table_name(old_name)}
RENAME TO #{quote_table_name(new_name)}
SQL
end
def rename_constraint(table_name, old_name, new_name)
<<~SQL
ALTER TABLE #{quote_table_name(table_name)}
RENAME CONSTRAINT #{quote_column_name(old_name)} TO #{quote_column_name(new_name)}
SQL
end
end
end
end
end
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