panbingkun commented on PR #46655:
URL: https://github.com/apache/spark/pull/46655#issuecomment-2126624184
Through comparative analysis, it is found that
1. In version `2.x`, there is `no distinction` between `signed` and
`unsigned`. For example, a type is defined in MySQL: `med MEDIUMINT UNSIGNED`
Through the `mariadb jdbc driver`, the final logic is:
https://github.com/mariadb-corporation/mariadb-connector-j/blob/maintenance/2.x/src/main/java/org/mariadb/jdbc/MariaDbResultSetMetaData.java#L283
<img width="490" alt="image"
src="https://github.com/apache/spark/assets/15246973/2a2987e7-6229-4c8f-b190-4637814c4ab7";>
https://github.com/mariadb-corporation/mariadb-connector-j/blob/maintenance/2.x/src/main/java/org/mariadb/jdbc/internal/ColumnType.java#L73
<img width="619" alt="image"
src="https://github.com/apache/spark/assets/15246973/a89e2f1c-820e-441d-8d66-2262d7711d97";>
** `Types.INTEGER` will be returned to `Spark` **
On the Spark side, we will go to the following logic:
https://github.com/apache/spark/blob/14d3f447360b66663c8979a8cdb4c40c480a1e04/sql/core/src/main/scala/org/apache/spark/sql/jdbc/MySQLDialect.scala#L148-L151
** Therefore, `Interger` will be finally obtained. **
2. In version `3.x`, there is a `distinction` between `signed` and
`unsigned`. For example, a type is defined in MySQL: `med MEDIUMINT UNSIGNED`
Through the `mariadb jdbc driver`, the final logic is:
https://github.com/mariadb-corporation/mariadb-connector-j/blob/master/src/main/java/org/mariadb/jdbc/client/result/ResultSetMetaData.java#L232-L234
<img width="578" alt="image"
src="https://github.com/apache/spark/assets/15246973/c34bae4e-06db-4e41-82a2-325c50abe42c";>
https://github.com/mariadb-corporation/mariadb-connector-j/blob/master/src/main/java/org/mariadb/jdbc/client/result/ResultSetMetaData.java#L297-L302
<img width="659" alt="image"
src="https://github.com/apache/spark/assets/15246973/036a0544-ffa2-4dec-a0fb-c6439c888988";>
**UnsignedMediumIntColumn**
https://github.com/mariadb-corporation/mariadb-connector-j/blob/master/src/main/java/org/mariadb/jdbc/client/column/UnsignedMediumIntColumn.java
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