Connection = ref object
  conn*: PSqlite3
  isBusy*: bool
  createdAt*: int64

Connections = ref object
  conns*: seq[Connection]
  timeout*: int              ## `getFreeConn` が接続を待つときに積む Future。`returnConn` が先頭から 1 件だけ完了させる。
  waiters*: Deque[Future[void]] ## `exec` / `insertId` 用。テーブルごとに PRAGMA table_info の結果を初回のみ保持する。
  columnTypeCache*: Table[string, seq[(string, string)]]

RawSqliteQuery = ref object
  log*: LogSetting
  pools*: Connections
  query*: JsonNode
  queryString*: string
  placeHolder*: JsonNode
  isInTransaction*: bool
  transactionConn*: int

SQLite3 = object

SqliteConnections = ref object
  log*: LogSetting
  pools*: Connections
  isInTransaction*: bool
  transactionConn*: int

SqliteQuery = ref object
  log*: LogSetting
  pools*: Connections
  query*: JsonNode
  queryString*: string
  placeHolder*: JsonNode
  isInTransaction*: bool
  transactionConn*: int