discourse/lib/migration/table_dropper.rb
Sam 5f64fd0a21 DEV: remove exec_sql and replace with mini_sql
Introduce new patterns for direct sql that are safe and fast.

MiniSql is not prone to memory bloat that can happen with direct PG usage.
It also has an extremely fast materializer and very a convenient API

- DB.exec(sql, *params) => runs sql returns row count
- DB.query(sql, *params) => runs sql returns usable objects (not a hash)
- DB.query_hash(sql, *params) => runs sql returns an array of hashes
- DB.query_single(sql, *params) => runs sql and returns a flat one dimensional array
- DB.build(sql) => returns a sql builder

See more at: https://github.com/discourse/mini_sql
2018-06-19 16:13:36 +10:00

78 lines
2.1 KiB
Ruby

require_dependency 'migration/base_dropper'
module Migration
class Migration::TableDropper < BaseDropper
def self.delayed_drop(table_name:, after_migration:, delay: nil, on_drop: nil)
validate_table_name(table_name)
TableDropper.new(table_name, nil, after_migration, delay, on_drop).delayed_drop
end
def self.delayed_rename(old_name:, new_name:, after_migration:, delay: nil, on_drop: nil)
validate_table_name(old_name)
validate_table_name(new_name)
TableDropper.new(old_name, new_name, after_migration, delay, on_drop).delayed_drop
end
def self.read_only_table(table_name)
create_readonly_function(table_name)
DB.exec <<~SQL
CREATE TRIGGER #{readonly_trigger_name(table_name)}
BEFORE INSERT OR UPDATE OR DELETE OR TRUNCATE
ON #{table_name}
FOR EACH STATEMENT
EXECUTE PROCEDURE #{readonly_function_name(table_name)};
SQL
end
private
def initialize(old_name, new_name, after_migration, delay, on_drop)
super(after_migration, delay, on_drop)
@old_name = old_name
@new_name = new_name
end
def droppable?
builder = DB.build(<<~SQL)
SELECT 1
FROM INFORMATION_SCHEMA.TABLES
/*where*/
LIMIT 1
SQL
builder.where(table_exists(":new_name")) if @new_name.present?
builder.where("table_schema = 'public'")
.where(table_exists(":old_name"))
.where(previous_migration_done)
.exec(old_name: @old_name,
new_name: @new_name,
delay: "#{@delay} seconds",
after_migration: @after_migration) > 0
end
def table_exists(table_name_placeholder)
<<~SQL
EXISTS(
SELECT 1
FROM INFORMATION_SCHEMA.TABLES
WHERE table_schema = 'public' AND
table_name = #{table_name_placeholder}
)
SQL
end
def execute_drop!
DB.exec("DROP TABLE IF EXISTS #{@old_name}")
DB.exec <<~SQL
DROP FUNCTION IF EXISTS #{BaseDropper.readonly_function_name(@old_name)} CASCADE;
SQL
end
end
end