{"record":{"id":"4293814e9cc14c49","repo":"apache/seatunnel","slug":"failed-to-analyze-sql-complexity-using-explain-fa","errorCode":null,"errorMessage":"Failed to analyze SQL complexity using EXPLAIN, fallback to default true. e: {}","messagePattern":"Failed to analyze SQL complexity using EXPLAIN, fallback to default true\\. e: (.+?)","errorType":"console","errorClass":null,"httpStatus":null,"severity":"warning","filePath":"seatunnel-connectors-v2/connector-clickhouse/src/main/java/org/apache/seatunnel/connectors/seatunnel/clickhouse/util/ClickhouseProxy.java","lineNumber":537,"sourceCode":"\n                    if (explainLine.contains(\"JOIN\")\n                            || explainLine.contains(\"UNION\")\n                            || explainLine.contains(\"GROUP BY\")\n                            || explainLine.contains(\"LIMIT\")\n                            || explainLine.contains(\"Sorting\")\n                            || explainLine.contains(\"Aggregating\")\n                            || explainLine.contains(\"Merging\")\n                            || explainLine.contains(\"subquery\")) {\n\n                        log.info(\"Complex SQL detected, explain line: {}\", explainLine);\n\n                        return true;\n                    }\n                }\n                return false;\n            }\n        } catch (Exception e) {\n            log.warn(\n                    \"Failed to analyze SQL complexity using EXPLAIN, fallback to default true. e: {}\",\n                    e.getMessage());\n            return true;\n        }\n    }\n\n    public void close() {\n        if (this.client != null) {\n            this.client.close();\n        }\n        shardToDataSource.values().forEach(ClickHouseClient::close);\n    }\n}\n","sourceCodeStart":519,"sourceCodeEnd":551,"githubUrl":"https://github.com/apache/seatunnel/blob/cf67b549a7a6c35fa0beb12d83c62892427ea919/seatunnel-connectors-v2/connector-clickhouse/src/main/java/org/apache/seatunnel/connectors/seatunnel/clickhouse/util/ClickhouseProxy.java#L519-L551","documentation":"ClickhouseProxy.isComplexSql runs an EXPLAIN (ESTIMATE) query against ClickHouse to decide whether the SQL is 'complex' (needing special handling). Any exception during this analysis logs this warning with the exception message and falls back to returning true (treated as complex).","triggerScenarios":"isComplexSql executes EXPLAIN on the connection and an Exception is thrown — syntax not supported by the ClickHouse version, connection failure, or permission issues.","commonSituations":"Older ClickHouse versions lacking EXPLAIN ESTIMATE; read-only user without EXPLAIN privileges; SQL dialect differences after version upgrades.","solutions":["Check the logged exception message; upgrade ClickHouse or the connector if EXPLAIN ESTIMATE is unsupported.","Grant the user permission to run EXPLAIN queries.","Accept the safe fallback (treated as complex) if the resulting behavior is acceptable."],"exampleFix":null,"handlingStrategy":"fallback","validationCode":"// pre-flight check\ntry (Statement st = conn.createStatement()) {\n    st.execute(\"EXPLAIN ESTIMATE \" + sql);\n}","typeGuard":null,"tryCatchPattern":"try {\n    boolean complex = proxy.isComplexSql(sql);\n} catch (Exception e) {\n    // connector falls back to true (complex); acceptable default\n}","preventionTips":["Verify EXPLAIN ESTIMATE support on your ClickHouse version","Grant EXPLAIN privileges to the query user","Run the pre-flight EXPLAIN check during deployment"],"tags":["clickhouse","sql","explain","fallback"],"backgroundTag":"sql-query-failed","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"}