Migration Troubleshooting
Common issues when migrating Glue Data Catalog tables to S3 Tables.
CTAS Errors
| Problem | Cause | Fix |
|---|---|---|
GENERIC_INTERNAL_ERROR: Invalid table or column names |
Uppercase in table or column names | Lowercase all names in the CTAS SELECT and table name |
| CTAS times out | Table too large for single Athena query | Use Glue ETL (Path B) or migrate in partitioned batches |
LOCATION is not supported |
Included LOCATION clause in CTAS | Remove LOCATION -- S3 Tables manages storage automatically |
SYNTAX_ERROR: line X:Y: mismatched input |
Malformed partition transform or missing quotes | Check partitioning = ARRAY[...] syntax and quote the catalog path |
TABLE_NOT_FOUND on source |
Wrong catalog prefix for source table | Use awsdatacatalog as the source catalog for standard Glue tables |
Validation Failures
| Problem | Cause | Fix |
|---|---|---|
| Row count mismatch | WHERE filter excluded rows, or source has duplicates | Check filter clause; run dedup analysis on source |
| Schema mismatch (extra/missing columns) | SELECT * picked up partition columns or metadata | Explicitly list columns in SELECT |
| Null count differs | Type coercion converted empty strings to nulls | Check source data for empty strings vs actual nulls |
| Boundary values differ | Timezone or precision differences | Compare with explicit CAST to same type |
Visibility Issues
| Problem | Cause | Fix |
|---|---|---|
| Target table not visible in Athena | Analytics integration not enabled | Create s3tablescatalog federated catalog. See ctas-patterns.md for catalog path syntax. |
| Table visible but returns no data | CTAS succeeded but wrote zero rows | Check WHERE filter; verify source table has data |
Table visible but columns show as _col0, _col1 |
Used SELECT * with incompatible source format | Explicitly name columns with aliases |
Partition Issues
| Problem | Cause | Fix |
|---|---|---|
| CTAS fails with too many partitions | Over 100 target partitions in single CTAS | Batch with WHERE filters or use coarser partition transform (e.g., month() instead of day()) |
| Partition column missing in target | Iceberg hidden partitions derive from source column | The source column must be in the SELECT; the transform is in partitioning |
| Uneven partition sizes | Poor transform choice for data distribution | Consider bucket() for high-cardinality columns |
Glue ETL Issues
See glue-etl-migration.md for Glue-specific errors.