|          Product           |  Affected Versions  |  Related Issues   | Fixed In |
| :------------------------- | :------------------ | :---------------- | :------- |
| {{<product "ysql">}}       | {{<release "All">}} | {{<issue 20864>}} | N/A      |

## Description

Foreign key checks may erroneously fail when writes impacting the foreign key check are done in the same statement.

## Mitigation

Upgrade to a release with the fix.

## Details

To enhance YugabyteDB's performance, optimization occurs in the buffering of reads and writes in the PostgreSQL layer before sending them to DocDB in a single request. This reduces the number of round trips between PostgreSQL and DocDB, resulting in improved efficiency.

- The table contains multiple foreign keys, with one of them being self-referencing.
- During write operations, there are typically at least two statements. One of these writes impacts the foreign key check for another write operation.

## Examples

An example schema on the database is as follows:

```sql
CREATE TABLE company(k INT PRIMARY KEY)"));
CREATE TABLE employee(
      k INT PRIMARY KEY, company_fk INT, manager_fk INT,
      UNIQUE(k, company_fk),
      FOREIGN KEY (company_fk) REFERENCES company(k),
      FOREIGN KEY (manager_fk, company_fk) REFERENCES employee(company_fk, k)))
);

Query Which will provide an error:
INSERT INTO employee VALUES (1, 1, NULL), (2, 1, 1), (3, 1, 1));
```

Query that results in an error:

```sql
INSERT INTO employee VALUES (1, 1, NULL), (2, 1, 1), (3, 1, 1));
```

## Related Articles

- List example on [GitHub](https://github.com/yugabyte/yugabyte-db/issues/20864#issuecomment-1939055452)