Class: QueryGuard::Migrations::TableSizeResolver

Inherits:
Object
  • Object
show all
Defined in:
lib/query_guard/migrations/table_size_resolver.rb

Overview

Extracts table names from Rails migration code

Pragmatically identifies which tables a migration affects by parsing common Rails migration method calls.

Detects: add_column, remove_column, change_column, create_table, drop_table, etc. on both active table operations and raw SQL.

Class Method Summary collapse

Class Method Details

.affected_tables(migration_content) ⇒ Array<String>

Extract table names that schema changes would directly affect

Parameters:

  • migration_content (String) —

    Migration file content

Returns:

  • (Array<String>) —

    Directly affected tables



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# File 'lib/query_guard/migrations/table_size_resolver.rb', line 146

def self.affected_tables(migration_content)
  all_tables = extract_table_names(migration_content)
  filter_schema_tables(all_tables)
end

.extract_table_names(migration_content) ⇒ Array<String>

Extract all table names referenced in a migration

Parameters:

  • migration_content (String) —

    Migration file content

Returns:

  • (Array<String>) —

    Table names (deduplicated)



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# File 'lib/query_guard/migrations/table_size_resolver.rb', line 17

def self.extract_table_names(migration_content)
  tables = Set.new

  lines = migration_content.lines

  lines.each do |line|
    next if line.strip.start_with?("#")
    next if line.strip.empty?

    # Try to capture table name: could be :symbol or "string" or 'string'
    # add_column :users, :name, :string
    if line.include?("add_column")
      # Match: add_column :table_name or add_column "table_name" or add_column 'table_name'
      if match = line.match(/add_column\s+[:"`']?(\w+)/)
        tables << match[1]
      end
    end

    # remove_column :posts, :old_field
    if line.include?("remove_column")
      if match = line.match(/remove_column\s+[:"`']?(\w+)/)
        tables << match[1]
      end
    end

    # change_column :users, :email, :text
    if line.include?("change_column")
      if match = line.match(/change_column\s+[:"`']?(\w+)/)
        tables << match[1]
      end
    end

    # rename_column :users, :old_name, :new_name
    if line.include?("rename_column")
      if match = line.match(/rename_column\s+[:"`']?(\w+)/)
        tables << match[1]
      end
    end

    # add_index :users, :email
    if line.include?("add_index")
      if match = line.match(/add_index\s+[:"`']?(\w+)/)
        tables << match[1]
      end
    end

    # remove_index :users, :email
    if line.include?("remove_index")
      if match = line.match(/remove_index\s+[:"`']?(\w+)/)
        tables << match[1]
      end
    end

    # drop_table :posts
    if line.include?("drop_table")
      if match = line.match(/drop_table\s+[:"`']?(\w+)/)
        tables << match[1]
      end
    end

    # create_table :accounts do ... end
    if line.include?("create_table")
      if match = line.match(/create_table\s+[:"`']?(\w+)/)
        tables << match[1]
      end
    end

    # Raw SQL UPDATE public.users SET ...
    if line.upcase.include?("UPDATE")
      if match = line.match(/UPDATE\s+(?:public\.)?(\w+)/i)
        tables << match[1]
      end
    end

    # Raw SQL DELETE FROM public.users
    if line.upcase.include?("DELETE")
      if match = line.match(/DELETE\s+FROM\s+(?:public\.)?(\w+)/i)
        tables << match[1]
      end
    end

    # Raw SQL INSERT INTO public.users
    if line.upcase.include?("INSERT")
      if match = line.match(/INSERT\s+INTO\s+(?:public\.)?(\w+)/i)
        tables << match[1]
      end
    end

    # Model.update_all(status: 'active') - convert model to table name
    # or User.delete_all
    if (line.include?("update_all") || line.include?("delete_all"))
      if match = line.match(/(\b[A-Z]\w*)\s*\.\s*(?:update_all|delete_all)/)
        model_name = match[1]
        # Convert CamelCase to snake_case: User -> user, UserProfile -> user_profile
        table_name = model_name
          .gsub(/([A-Z])/, '_\1')
          .downcase
          .sub(/^_/, '')
        # Pluralize simple table names: add 's' for most words
        # This is a simple heuristic; full pluralization would require a library
        table_name = table_name + 's' unless table_name.end_with?('s', 'x', 'z')
        tables << table_name if table_name && !table_name.empty?
      end
    end
  end

  tables.to_a.sort
end

.filter_schema_tables(table_names) ⇒ Array<String>

Filter tables to only those likely affected by schema changes

Excludes internal Rails tables like schema_migrations

Parameters:

  • table_names (Array<String>) —

    List of table names

Returns:

  • (Array<String>) —

    Filtered list



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# File 'lib/query_guard/migrations/table_size_resolver.rb', line 132

def self.filter_schema_tables(table_names)
  # Internal rails tables to ignore
  internal_tables = %w[
    schema_migrations ar_internal_metadata
    delayed_jobs sidekiq_jobs
  ]

  table_names.reject { |name| internal_tables.include?(name) }
end