discourse/lib/migration/column_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

65 lines
1.9 KiB
Ruby

require_dependency 'migration/base_dropper'
module Migration
class ColumnDropper < BaseDropper
def self.drop(table:, after_migration:, columns:, delay: nil, on_drop: nil)
validate_table_name(table)
columns.each { |column| validate_column_name(column) }
ColumnDropper.new(table, columns, after_migration, delay, on_drop).delayed_drop
end
def self.mark_readonly(table_name, column_name)
create_readonly_function(table_name, column_name)
DB.exec <<~SQL
CREATE TRIGGER #{readonly_trigger_name(table_name, column_name)}
BEFORE INSERT OR UPDATE OF #{column_name}
ON #{table_name}
FOR EACH ROW
WHEN (NEW.#{column_name} IS NOT NULL)
EXECUTE PROCEDURE #{readonly_function_name(table_name, column_name)};
SQL
end
private
def initialize(table, columns, after_migration, delay, on_drop)
super(after_migration, delay, on_drop)
@table = table
@columns = columns
end
def droppable?
builder = SqlBuilder.new(<<~SQL)
SELECT 1
FROM INFORMATION_SCHEMA.COLUMNS
/*where*/
LIMIT 1
SQL
builder.where("table_schema = 'public'")
.where("table_name = :table")
.where("column_name IN (:columns)")
.where(previous_migration_done)
.exec(table: @table,
columns: @columns,
delay: "#{@delay} seconds",
after_migration: @after_migration).to_a.length > 0
end
def execute_drop!
@columns.each do |column|
DB.exec <<~SQL
DROP TRIGGER IF EXISTS #{BaseDropper.readonly_trigger_name(@table, column)} ON #{@table};
DROP FUNCTION IF EXISTS #{BaseDropper.readonly_function_name(@table, column)} CASCADE;
SQL
# safe cause it is protected on method entry, can not be passed in params
DB.exec("ALTER TABLE #{@table} DROP COLUMN IF EXISTS #{column}")
end
end
end
end