불필요한 JDBC 설정 걷어내기

url: jdbc:mariadb://${DB_HOST}:3306/db?autoReconnect=true&useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC&tinyInt1isBit=false

autoReconnect=true

• JDBC에서 제공하는 방법으로 연결이 끊어졌을 때 JDBC 드라이버가 자동으로 연결을 재시도하도록 할 수 있다. 하지만 이 경우 데이터 일관성이 틀어지는 이슈가 발생할 수 있으므로 권장되지 않는다.

Although not recommended, you can make the driver perform failovers without invalidating the active Statement or ResultSet instances by setting either the parameter autoReconnect or autoReconnectForPools to true. This allows the client to continue using the same object instances after a failover event, without taking any exceptional measures. This, however, may lead to unexpected results: for example, if the driver is connected to the primary host with read/write access mode and it fails-over to a secondary host in read-only mode, further attempts to issue data-changing queries will result in errors, and the client will not be aware of that. This limitation is particularly relevant when using data streaming: after the failover, the ResultSet looks to be alright, but the underlying connection may have changed already, and no backing cursor is available anymore.

MySQL :: MySQL Connector/J Developer Guide :: 9.1 Configuring Server Failover for Connections Using JDBC

MySQL Connector/J supports server failover. A failover happens when connection-related errors occur for an underlying, active connection. The connection errors are, by default, propagated to the client, which has to handle them by, for example, recreating the working objects (Statement, ResultSet, etc.) and restarting the processes. Sometimes, the driver might eventually fall back to the original host automatically before the client application continues to run, in which case the host switch is transparent and the client application will not even notice it.

https://dev.mysql.com/doc/connector-j/en/connector-j-config-failover.html

useUnicode=true&characterEncoding=UTF-8

• 예전에 유니코드 문자들을 올바로 처리하여 UTF-8로 인코딩 될 수 있도록 사용하던 설정이다.

• 하지만 최근에는 UTF-8이 기본 설정이기에 특별히 지정할 필요가 없는 설정이며, 특히나 useUnicode의 경우에는 현재는 공식 문서에서도 찾아볼 수 없는, 사용하지 않는 설정이다.

• 문자 인코딩 설정에 대한 우선 순위가 있는데, 아래 설정들이 있다면 그 우선 순위에 따라 설정되고 어느 것도 설정되어 있지 않은 경우에는 UTF-8로 설정된다.
• passwordCharacterEncoding
• connectionCollation
• characterEncoding

MySQL :: MySQL Connector/J Developer Guide :: 6.7 Using Character Sets and Unicode

All strings sent from the JDBC driver to the server are converted automatically from native Java Unicode form to the connection's character encoding, including all queries sent using Statement.execute(), Statement.executeUpdate(), and Statement.executeQuery(), as well as all PreparedStatement and CallableStatement parameters, excluding parameters set using the following methods:

https://dev.mysql.com/doc/connector-j/en/connector-j-reference-charsets.html

passwordCharacterEncoding=UTF-8

• 위 내용과 마찬가지로 기본 설정이 UTF-8이므로 특별한 경우가 아니라면 다시 설정할 필요가 없다.

MySQL :: MySQL Connector/J Developer Guide :: 6.7 Using Character Sets and Unicode

All strings sent from the JDBC driver to the server are converted automatically from native Java Unicode form to the connection's character encoding, including all queries sent using Statement.execute(), Statement.executeUpdate(), and Statement.executeQuery(), as well as all PreparedStatement and CallableStatement parameters, excluding parameters set using the following methods:

https://dev.mysql.com/doc/connector-j/en/connector-j-reference-charsets.html

serverTimezone=UTC

Former connection option 'serverTimezone' is still valid as an alias of this one but may be deprecated in the future.

By default, the connector adopts the JVM's default time zone. If the client and server reside in different time zones, it's recommended to configure the connection time zone to match the JVM's default by setting forceConnectionTimeZoneToSession to true. This ensures proper operation of time functions.

• 현재는 존재하지 않는 옵션명이며, connectionTimeZone으로 변경되었다.

• 기본적으로 timeZone은 서버의 시간대를 따른다. connectionTimeZone으로 시간대를 지정하려면, forceConnectionTimeZoneToSession 설정을 활성화하여야 한다.

• JVM의 시간대에 따라 timeZone을 설정하도록 하는 것이 기본 설정이기 때문에 forceConnectionTimeZoneToSession은 기본적으로 비활성화 되어 있다.

MySQL :: MySQL Connector/J Developer Guide :: 6.3.11 Datetime types processing

Configures the connection time zone which is used by Connector/J if conversion between the JVM default and a target time zone is needed when preserving instant temporal values.

https://dev.mysql.com/doc/connector-j/en/connector-j-connp-props-datetime-types-processing.html#cj-conn-prop_connectionTimeZone

About MariaDB Connector/J

LGPL-licensed MariaDB client library for Java applications.

https://mariadb.com/kb/en/about-mariadb-connector-j/

tinyInt1isBit=false

Datatype mapping flag, handle MySQL Tiny as BIT(boolean)-

BOOL, BOOLEAN These types are synonyms for TINYINT(1). A value of zero is considered false. Nonzero values are considered true:

• tinyint(1) 값을 BOOLEAN으로 처리할지 여부를 결정한다. 기본값은 true로, tinyint(1)은 BOOLEAN으로 반환된다.

• MySQL, MariaDB 등에는 Boolean 역할을 하는 Type이 없다. 그래서 tinyint(1)을 BOOLEAN으로 사용하고 있다.

• 선택의 문제이지만 사실 tinyint(2)이런 식으로 한다고 하더라도 표현 범위는 tinyint(4) 등과 동일하다. 이는 tinyint(1)을 BOOLEAN이 아니라 tinyint로 처리되도록 해도 큰 이점이 없다는 의미이다.

For integer data types, M indicates the minimum display width. The maximum display width is 255. Display width is unrelated to the range of values a type can store, as described in Section 13.1.6, “Numeric Type Attributes”.

• 주요 데이터베이스 시스템들(MySQL, PostgreSQL, Oracle 등)에서는 정수형 타입의 저장 크기를 직접 지정하는 기능을 제공하지 않는다. 대신 미리 정의된 크기의 정수형 타입(TINYINT, SMALLINT, INT, BIGINT 등)을 사용하여 적절한 크기를 선택해야 한다.

MySQL Bugs: #100722: tinyInt1isBit Configuration Property Is No Longer Honored

Portions of this website are copyright © 2001, 2002 The PHP Group

https://bugs.mysql.com/bug.php?id=100722

MySQL :: MySQL 8.4 Reference Manual :: 13.1.1 Numeric Data Type Syntax

For integer data types, M indicates the minimum display width. The maximum display width is 255. Display width is unrelated to the range of values a type can store, as described in Section 13.1.6, “Numeric Type Attributes”.

https://dev.mysql.com/doc/refman/8.4/en/numeric-type-syntax.html

정리

url: jdbc:mariadb://${DB_HOST}:3306/db