What causes "Generate Splits for table %s error" in apache/seatunnel?

Inspect the chained cause to identify the specific underlying failure

apache/seatunnel · error · RuntimeException

Generate Splits for table %s error

Error message

Generate Splits for table %s error

What it means

A catch-all wrapper thrown at the end of generateSplits() when any unexpected exception occurs while splitting the table into snapshot chunks. It catches everything not already converted into the more specific errors (discovery, SQLException) and attaches the table id, with the real cause chained.

Source

Thrown at seatunnel-connectors-v2/connector-cdc/connector-cdc-base/src/main/java/org/apache/seatunnel/connectors/cdc/base/source/enumerator/splitter/AbstractJdbcSourceChunkSplitter.java:130

                                    jdbc,
                                    tableId,
                                    i,
                                    splitType,
                                    chunk.getChunkStart(),
                                    chunk.getChunkEnd());
                    splits.add(split);
                }
            }

            long end = System.currentTimeMillis();
            log.info(
                    "Split table {} into {} chunks, time cost: {}ms.",
                    tableId,
                    splits.size(),
                    end - start);
            return splits;
        } catch (Exception e) {
            throw new RuntimeException(
                    String.format("Generate Splits for table %s error", tableId), e);
        }
    }

    private List<ChunkRange> splitTableIntoChunks(
            JdbcConnection jdbc, TableId tableId, Column splitColumn) throws Exception {
        final String splitColumnName = splitColumn.name();
        final Object[] minMax = queryMinMax(jdbc, tableId, splitColumn);
        final Object min = minMax[0];
        final Object max = minMax[1];
        if (min == null || max == null || min.equals(max)) {
            // empty table, or only one row, return full table scan as a chunk
            return Collections.singletonList(ChunkRange.all());
        }

        final int chunkSize = sourceConfig.getSplitSize();
        final double distributionFactorUpper = sourceConfig.getDistributionFactorUpper();
        final double distributionFactorLower = sourceConfig.getDistributionFactorLower();

View on GitHub (pinned to cf67b549a7)

Solutions

Inspect the chained cause to identify the specific underlying failure
Check the split column's data type; choose a numeric, date, or string PK/unique key with a supported type
Update the JDBC driver / SeaTunnel connector version if the cause points to a driver bug
Reduce chunk size or exclude the problematic table to isolate the issue

Defensive patterns

Strategy: try-catch

Validate before calling

// Verify the split column type is supported before splitting:
SELECT DATA_TYPE FROM information_schema.COLUMNS WHERE TABLE_SCHEMA='db' AND TABLE_NAME='t' AND COLUMN_NAME='id';

Try / catch

try { return generateSplits(tableId); } catch (RuntimeException e) {
    LOG.error("Split failed for {} cause={}", tableId, e.getCause(), e);
    throw e;
}

Prevention

Use simple numeric/date PK columns as split keys
Keep JDBC driver and connector versions current
Test chunk splitting on production-like table shapes

When it happens

Trigger: Any Exception escaping the split procedure: query-building errors, unexpected driver behavior, failure computing split types (getSplitType), errors in queryEvenlySplitChunks / chunk boundary arithmetic, OOM-like driver errors inside splitting.

Common situations: Unusual column types chosen as the split key; driver version quirks; extremely skewed or huge tables; a bug/edge case in a specific dialect's splitter implementation.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/a4d89dc85598142d. Report an issue: GitHub.