fix(mysql): fail fast on partial JSON binlog events (PARTIAL_JSON)#4538
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When binlog_row_value_options=PARTIAL_JSON is enabled at runtime on the source, MySQL emits PARTIAL_UPDATE_ROWS_EVENT carrying JSON diffs instead of full values. go-mysql parses these as a *RowsEvent, but PeerDB's inner event-type switch had no case for it and no default, so the entire update (all columns) was silently dropped after its bytes were counted as consumed — CDC advanced past it, causing silent data loss. Add a PARTIAL_UPDATE_ROWS_EVENT case that fails fast with a classified error (NOTIFY_BINLOG_PARTIAL_JSON_UNSUPPORTED) telling the user to disable binlog_row_value_options and resync, plus a default branch so any future rows-event subtype errors loudly instead of dropping data. The JsonDiff value conversion now errors as a defensive backstop. Scoped to tables in the pipe via the existing `schema != nil` guard. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Code reviewNo issues found. Checked for bugs and CLAUDE.md compliance. |
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Code reviewNo issues found. Checked for bugs and CLAUDE.md compliance. |
jgao54
approved these changes
Jul 6, 2026
ilidemi
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Jul 7, 2026
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| if _, ok := errors.AsType[*exceptions.MySQLUnsupportedBinlogRowValueOptionsError](err); ok { | ||
| return ErrorNotifyBinlogPartialJsonUnsupported, ErrorInfo{ |
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Problem
binlog_row_value_optionsis a dynamic, session-settable MySQL variable, so it can be set toPARTIAL_JSONat runtime after a mirror passes creation-time validation. When enabled, MySQL emitsPARTIAL_UPDATE_ROWS_EVENT(event type 39) carrying JSON diffs instead of full column values.go-mysql parses these into a
*replication.RowsEvent, so the event reaches PeerDB'scase *replication.RowsEvent:normally. But the inner event-type switch had no case forPARTIAL_UPDATE_ROWS_EVENTand nodefault— so the entire update (all columns, not just the JSON one) was silently dropped after its bytes were already counted as consumed. CDC advanced past it → silent data loss.Fix
PARTIAL_UPDATE_ROWS_EVENTcase that fails fast with a new classified error (MySQLUnsupportedBinlogRowValueOptionsError→NOTIFY_BINLOG_PARTIAL_JSON_UNSUPPORTED), instructing the user to disablebinlog_row_value_optionsand resync.🤖 Generated with Claude Code