yuxiqian commented on code in PR #2968:
URL: https://github.com/apache/flink-cdc/pull/2968#discussion_r1675421946
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flink-cdc-connect/flink-cdc-source-connectors/flink-connector-mysql-cdc/src/main/java/org/apache/flink/cdc/connectors/mysql/source/utils/ObjectUtils.java:
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@@ -89,6 +95,48 @@ public static int compare(Object obj1, Object obj2) {
}
}
+ /**
+ * Compares two comparable objects. When the compared objects are not
instance of {@link
+ * Comparable} or instace of String, we will compare them in db, ignore
the charset of table
+ * effects the table-split result exmaple: primaryKey:
+ * ['0000','1111','2222','3333','4444','aaaa','bbbb','cccc','ZZZZ']
collate: utf8mb4_general_ci
+ * when chunkSize = 3 we want : split1: ['0000','1111'] split2:
['3333','4444'] split3:
+ * ['aaaa','bbbb'] split3: ['cccc','ZZZZ'] but if we use a table with
+ * COLLATE='utf8mb4_general_ci' and compare them with {@link
ObjectUtils#compare(Object,
+ * Object)}, we whill get: split1: ['0000','1111'] split2: ['3333','4444']
split3:
+ * ['aaaa','bbbb','cccc','ZZZZ'....] the split3 whill contains all of the
remain rows
+ *
+ * @return The value {@code 0} if {@code num1} is equal to the {@code
num2}; a value less than
+ * {@code 0} if the {@code num1} is numerically less than the {@code
num2}; and a value
+ * greater than {@code 0} if the {@code num1} is numerically greater
than the {@code num2}.
+ * @throws ClassCastException if the compared objects are not instance of
{@link Comparable} or
+ * not <i>mutually comparable</i> (for example, strings and integers).
+ */
+ @SuppressWarnings("unchecked")
+ public static int dbCompare(
+ Object obj1,
+ Object obj2,
+ JdbcConnection jdbcConnection,
+ TableId tableId,
+ String splitColumn)
+ throws SQLException {
+ if (Objects.equals(obj1, obj2)) {
+ return 0;
+ }
+ if (obj1 instanceof String && obj2 instanceof String) {
+ // if instance of String, we will compare them in db, to ignore
effects of the charset
+ // and collation of the column
+ String columnCollation =
+ StatementUtils.queryColumnCollation(jdbcConnection,
tableId, splitColumn);
Review Comment:
Got it, this solution looks reasonable.
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