SML0127 commented on code in PR #4104:
URL: https://github.com/apache/flink-cdc/pull/4104#discussion_r2328628886
##########
flink-cdc-connect/flink-cdc-source-connectors/flink-connector-mysql-cdc/src/main/java/org/apache/flink/cdc/connectors/mysql/source/utils/StatementUtils.java:
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@@ -56,6 +61,31 @@ public static Object[] queryMinMax(JdbcConnection jdbc,
TableId tableId, String
});
}
+ public static Long queryRowCnt(
+ JdbcConnection jdbc, TableId tableId, String columnName, @Nullable
String filter)
+ throws SQLException {
+
+ if (filter == null) {
+ return queryApproximateRowCnt(jdbc, tableId);
+ }
+
+ final String cntQuery =
+ String.format(
+ "SELECT COUNT(%s) FROM %s WHERE %s",
+ quote(columnName), quote(tableId), filter);
+ return jdbc.queryAndMap(
+ cntQuery,
+ rs -> {
+ if (!rs.next()) {
+ // this should never happen
+ throw new SQLException(
+ String.format(
+ "No result returned after running
query [%s]", cntQuery));
+ }
+ return rs.getLong(1);
+ });
+ }
+
Review Comment:
Because the filter is applied during split planning, the distribution factor
may fall outside the configured bounds(0.05 ~1,000), affecting snapshot
performance. I’d appreciate your thoughts on this.
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