{"record":{"id":"aa6a4935baae080f","repo":"apache/seatunnel","slug":"cannot-obtain-valid-replication-slot-for-plug","errorCode":null,"errorMessage":"Cannot obtain valid replication slot '{}' for plugin '{}' and database '{}' [during attempt {} out of {}, concurrent tx probably blocks taking snapshot.","messagePattern":"Cannot obtain valid replication slot '(.+?)' for plugin '(.+?)' and database '(.+?)' \\[during attempt (.+?) out of (.+?), concurrent tx probably blocks taking snapshot\\.","errorType":"console","errorClass":null,"httpStatus":null,"severity":"warning","filePath":"seatunnel-connectors-v2/connector-cdc/connector-cdc-opengauss/src/main/java/io/debezium/connector/postgresql/connection/PostgresConnection.java","lineNumber":341,"sourceCode":"     *     ServerInfo.ReplicationSlot#INVALID} if the slot is not valid\n     * @throws SQLException is thrown by the underyling jdbc driver\n     * @throws InterruptedException is thrown if we don't return an answer within the set number of\n     *     retries\n     */\n    @VisibleForTesting\n    ServerInfo.ReplicationSlot readReplicationSlotInfo(String slotName, String pluginName)\n            throws SQLException, InterruptedException {\n        final String database = database();\n        final Metronome metronome =\n                Metronome.parker(PAUSE_BETWEEN_REPLICATION_SLOT_RETRIEVAL_ATTEMPTS, Clock.SYSTEM);\n\n        for (int attempt = 1; attempt <= MAX_ATTEMPTS_FOR_OBTAINING_REPLICATION_SLOT; attempt++) {\n            final ServerInfo.ReplicationSlot slot = fetchReplicationSlotInfo(slotName, pluginName);\n            if (slot != null) {\n                LOGGER.info(\"Obtained valid replication slot {}\", slot);\n                return slot;\n            }\n            LOGGER.warn(\n                    \"Cannot obtain valid replication slot '{}' for plugin '{}' and database '{}' [during attempt {} out of {}, concurrent tx probably blocks taking snapshot.\",\n                    slotName,\n                    pluginName,\n                    database,\n                    attempt,\n                    MAX_ATTEMPTS_FOR_OBTAINING_REPLICATION_SLOT);\n            metronome.pause();\n        }\n\n        throw new ConnectException(\n                \"Unable to obtain valid replication slot. \"\n                        + \"Make sure there are no long-running transactions running in parallel as they may hinder the allocation of the replication slot when starting this connector\");\n    }\n\n    protected ServerInfo.ReplicationSlot queryForSlot(\n            String slotName,\n            String database,\n            String pluginName,","sourceCodeStart":323,"sourceCodeEnd":359,"githubUrl":"https://github.com/apache/seatunnel/blob/cf67b549a7a6c35fa0beb12d83c62892427ea919/seatunnel-connectors-v2/connector-cdc/connector-cdc-opengauss/src/main/java/io/debezium/connector/postgresql/connection/PostgresConnection.java#L323-L359","documentation":"This is a warning emitted while polling for a PostgreSQL/openGauss logical replication slot's info. The connector fetched the slot metadata via pg_replication_slots but got null (slot missing, or inactive with no confirmed_flush_lsn), meaning a concurrent transaction is likely holding back the slot snapshot/advance. It retries up to MAX_ATTEMPTS_FOR_OBTAINING_REPLICATION_SLOT times before failing hard with a DebeziumException.","triggerScenarios":"getReplicationSlotState -> readReplicationSlotInfo loop: fetchReplicationSlotInfo returns null on every attempt for the configured slotName/plugin/database — typically right after slot creation while another transaction is open, or when the slot was dropped externally.","commonSituations":"Long-running transactions on the database blocking WAL/slot snapshot export; another connector instance consumed or dropped the same slot; slot name typo so the slot does not exist; Postgres restart mid-setup.","solutions":["Verify the slot exists: SELECT slot_name, plugin, active FROM pg_replication_slots; and create it if missing (SELECT pg_create_logical_replication_slot('<slot>','<plugin>')).","Kill or wait for long-running transactions blocking the slot (SELECT pid, state, xact_start FROM pg_stat_activity WHERE state <> 'idle';).","Ensure each connector uses a unique replication slot name; sharing a slot across concurrent connectors causes contention.","Increase the retry window if transactions are expected (adjust MAX_ATTEMPTS_FOR_OBTAINING_REPLICATION_SLOT or slot.name config) and rerun."],"exampleFix":"// before: two connectors sharing slot 'dbz'\n{\"debezium.properties\": {\"slot.name\": \"dbz\"}} // connector A and B\n// after\n// connector A: {\"slot.name\": \"dbz_a\"}\n// connector B: {\"slot.name\": \"dbz_b\"}","handlingStrategy":"retry","validationCode":"SELECT slot_name, plugin, active, confirmed_flush_lsn FROM pg_replication_slots WHERE slot_name = '<slot>' AND plugin = '<plugin>'; -- require one active=false row before starting","typeGuard":null,"tryCatchPattern":"for (int attempt = 1; attempt <= 6; attempt++) { if (slotAvailable()) break; Thread.sleep(10_000 * attempt); }","preventionTips":["Verify slot exists and is inactive before starting the connector.","Give each connector a unique slot name.","Monitor pg_stat_activity for long-running transactions during startup."],"tags":["cdc","postgresql","replication-slot","retry"],"backgroundTag":"resource-not-found","analyzedSha":"cf67b549a7a6c35fa0beb12d83c62892427ea919","analyzedAt":"2026-09-10T21:44:55.265Z","contentChangedAt":"2026-09-10T21:44:55.265Z","schemaVersion":2},"datasetVersion":"2026-09-14T11:17:12.474Z"}