predator4ann commented on code in PR #6657:
URL: https://github.com/apache/gravitino/pull/6657#discussion_r2220395679
##########
catalogs/catalog-jdbc-common/src/main/java/org/apache/gravitino/catalog/jdbc/operation/JdbcTableOperations.java:
##########
@@ -626,4 +633,117 @@ protected JdbcColumn.Builder
getBasicJdbcColumnInfo(ResultSet column) throws SQL
.withNullable(nullable)
.withDefaultValue(defaultValue);
}
+
+ /**
+ * Calculate the precision for time/datetime/timestamp types.
+ *
+ * <p>This method provides a default behavior returning null for catalogs
that do not implement
+ * this method. Developers should override this method when their database
supports precision
+ * specification for datetime types.
+ *
+ * <p><strong>When to return null:</strong>
+ *
+ * <ul>
+ * <li>When the database does not support precision for datetime types
+ * <li>When the driver version is incompatible (e.g., MySQL driver <
8.0.16)
+ * <li>When the type is not a datetime type (TIME, TIMESTAMP, DATETIME)
+ * <li>When the precision cannot be accurately calculated from the
provided parameters
+ * </ul>
+ *
+ * <p><strong>When to return non-null:</strong>
+ *
+ * <ul>
+ * <li>When the database supports precision for datetime types and the
driver version is
+ * compatible
+ * <li>When the precision can be accurately calculated from columnSize
(e.g., columnSize -
+ * format_length)
+ * <li>For TIME types: return columnSize - 8 (for 'HH:MM:SS' format)
+ * <li>For TIMESTAMP/DATETIME types: return columnSize - 19 (for
'YYYY-MM-DD HH:MM:SS' format)
+ * </ul>
+ *
+ * <p><strong>Examples:</strong>
+ *
+ * <ul>
+ * <li>TIME(3) with columnSize=11: return 3 (11-8)
+ * <li>TIMESTAMP(6) with columnSize=25: return 6 (25-19)
+ * <li>DATETIME(0) with columnSize=19: return 0 (19-19)
+ * </ul>
+ *
+ * @param typeName the type name from database (e.g., "TIME", "TIMESTAMP",
"DATETIME")
+ * @param columnSize the column size from database (total length including
format and precision)
+ * @param scale the scale from database (usually 0 for datetime types)
+ * @return the precision of the time/datetime/timestamp type, or null if not
supported/calculable
+ */
+ public Integer calculateDatetimePrecision(String typeName, int columnSize,
int scale) {
+ return null;
+ }
+
+ /**
+ * Get MySQL driver version from DatabaseMetaData
+ *
+ * @return the driver version string, or null if not available
+ */
+ protected String getMySQLDriverVersion() {
+ try {
+ if (dataSource != null) {
+ try (Connection connection = dataSource.getConnection()) {
+ return connection.getMetaData().getDriverVersion();
+ }
+ }
+ } catch (SQLException e) {
+ LOG.debug("Failed to get driver version", e);
+ }
+ return null;
+ }
+
+ /**
+ * Check if driver version supports accurate columnSize for precision
calculation. For MySQL
+ * driver: Only versions >= 8.0.16 return accurate columnSize for
datetime precision. For other
+ * drivers (like OceanBase): Assume they support accurate precision
calculation
Review Comment:
done
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