Grail's assay-ingestion pipeline records each received sample in assay_ingestion_records. A repeated sample_identifier can indicate a retried upload or an upstream data-quality issue.
Write a PostgreSQL query to find non-null sample identifiers that occur more than once.
sample_identifier and the number of records using the alias duplicate_count.sample_identifier is NULL, and sort results by duplicate_count descending, then sample_identifier ascending.| Column | Type | Description |
|---|---|---|
| ingestion_idPK | INTEGER | Unique identifier for an ingestion record. |
| sample_identifier | VARCHAR(50) | Identifier assigned to an assay sample. |
| received_at | TIMESTAMP | Timestamp when the record was received. |
| source_system | VARCHAR(30) | System that submitted the ingestion record. |