maria: require resync on partial row events

[dtunikov]

We don't support partial row events. MariaDB 12.3+ emits those when payload size is bigger than binlog_row_event_fragment_threshold (default 1Gb).
This PR handles this event type and requires a resync.
In addition, it introduces UnsupportedBinlogEventCounter(eventType) metric to keep track of skipped events.

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

[jgao54]

a few nit comment but lgtm overall

[codecov]

❌ 2 Tests Failed:

Tests completed	Failed	Passed	Skipped
2954	2	2952	343

View the top 1 failed test(s) by shortest run time

github.com/PeerDB-io/peerdb/flow/e2e::TestPeerFlowE2ETestSuiteMariaDB_CH/Test_MariaDB_PartialRowEvent

Stack Traces | 195s run time

=== RUN   TestPeerFlowE2ETestSuiteMariaDB_CH/Test_MariaDB_PartialRowEvent
=== PAUSE TestPeerFlowE2ETestSuiteMariaDB_CH/Test_MariaDB_PartialRowEvent
=== CONT  TestPeerFlowE2ETestSuiteMariaDB_CH/Test_MariaDB_PartialRowEvent
2026/07/03 13:45:02 INFO fetched schema x-peerdb-additional-metadata={Operation:FLOW_OPERATION_UNKNOWN} table=e2e_test_mach_xsk2ix5z.test_mysql_schema_changes
    clickhouse_mysql_test.go:1957: WaitFor waiting for in-pipe row past out-of-pipe partial row event 2026-07-03 13:45:16.564518412 +0000 UTC m=+485.130611153
2026/07/03 13:45:16 INFO fetched schema x-peerdb-additional-metadata={Operation:FLOW_OPERATION_UNKNOWN} table=e2e_test_mach_1iwesbnb.test_blobs
2026/07/03 13:45:16 INFO fetched schema x-peerdb-additional-metadata={Operation:FLOW_OPERATION_UNKNOWN} table=e2e_test_mach_6zelra5m.test_bit
    clickhouse_mysql_test.go:1957: UNEXPECTED TIMEOUT waiting for in-pipe row past out-of-pipe partial row event 2026-07-03 13:48:17.177314151 +0000 UTC m=+665.743406874
--- FAIL: TestPeerFlowE2ETestSuiteMariaDB_CH/Test_MariaDB_PartialRowEvent (194.78s)

View the full list of 1 ❄️ flaky test(s)

github.com/PeerDB-io/peerdb/flow/e2e::TestPeerFlowE2ETestSuiteMariaDB_CH

Flake rate in main: 14.29% (Passed 24 times, Failed 4 times)

Stack Traces | 0.01s run time

=== RUN   TestPeerFlowE2ETestSuiteMariaDB_CH
=== PAUSE TestPeerFlowE2ETestSuiteMariaDB_CH
=== CONT  TestPeerFlowE2ETestSuiteMariaDB_CH
--- FAIL: TestPeerFlowE2ETestSuiteMariaDB_CH (0.01s)
2026/07/03 13:49:14 INFO Received AWS credentials from peer for connector: ci x-peerdb-additional-metadata={Operation:FLOW_OPERATION_UNKNOWN}
2026/07/03 13:49:14 INFO fetched schema x-peerdb-additional-metadata={Operation:FLOW_OPERATION_UNKNOWN} table=e2e_test_machcl_7ipudwcu.test_composite_pkey_ordering

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[github-actions]

❌ Test Failure

Analysis: The PR's own new test Test_MariaDB_PartialRowEvent fails deterministically across all three matrix jobs (mysql-gtid/pos, MySQL 6.0/7.0/8.0) after ~190s, indicating a real bug in the PR's partial-row-event resync logic rather than a flaky failure.
Confidence: 0.9

⚠️ This appears to be a real bug - manual intervention needed

View workflow run