SQLite3 gem中的类型转换做什么?

答案可以通过以下方式找到: examining the source code :

# Return the type translator employed by this database instance. Each
# database instance has its own type translator; this allows for different
# type handlers to be installed in each instance without affecting other
# instances. Furthermore, the translators are instantiated lazily, so that
# if a database does not use type translation, it will not be burdened by
# the overhead of a useless type translator. (See the Translator class.)

当你看到 Translator class :

# The Translator class encapsulates the logic and callbacks necessary for
# converting string data to a value of some specified type. Every Database
# instance may have a Translator instance, in order to assist in type
# translation (Database#type_translation).

因此,当 type_translation = true ,sqlite3将使用该数据库的类型转换器来协助在数据类型之间序列化数据。

从该链接: https://github.com/sparklemotion/sqlite3-ruby/blob/master/lib/sqlite3/database.rb

“…Database类还提供类型转换服务,通过该服务,SQLite3数据类型(均表示为字符串)可以转换为其相应的类型(如其表的模式中所定义)。这种转换仅在从数据库查询数据时发生——插入和更新都仍然是无类型的…”

https://sqlite.org/datatype3.html 它解释了sqlite3中如何处理数据类型。