| 1 | Derived tables that have a column with the xid type | Find the derived tables (views and materialized views) that have a column with the xid type, i.e., these use the data from the hidden xmin column of a base table. If one uses optimistic approach for dealing with the concurrent data modifications, then xmin values should be presented by views and used in routines that modify or delete rows. | General | INFORMATION_SCHEMA+system catalog base tables | 2020-11-06 14:51 | MIT License | |
| 2 | Explicit locking | PostgreSQL uses Multi-version Concurrency Control (MVCC) and thus, sometimes, one has to explicitly lock certain rows or entire table. One has to use LOCK TABLE or SELECT … FOR UPDATE statements for that. | General | INFORMATION_SCHEMA+system catalog base tables | 2023-12-11 15:02 | MIT License | |
| 3 | Explicit locking is missing | PostgreSQL uses multiversion concurrency control (MVCC). SELECTs do not block modifications and vice versa. One has to take steps to achieve correct behaviour. | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2024-12-13 14:57 | MIT License | |
| 4 | Explicit locking is missing (2) | Find user-defined routines that have a subquery in a DELETE or UPDATE statement without the FOR UPDATE clause. | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2023-12-06 12:15 | MIT License | |
| 5 | Explicit locking is probably not needed | You do not need explicit locking (LOCK TABLE or SELECT … FOR UPDATE) in case of routines that only search some data but do not modify any data and do not raise any exception. | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2021-11-04 12:08 | MIT License | |
| 6 | FOR UPDATE in derived tables | Find derived tables that subquery uses FOR UPDATE construct. Reading a data element shouldn't block other read operations of the same element. Thus, you shouldn't use exclusive locking command in a view. | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2022-12-12 11:11 | MIT License | |
| 7 | FOR UPDATE is not allowed with aggregate functions | Implement explicit locking correctly. Instead of writing, for instance, SELECT Count(*) AS cnt FROM person WHERE person_id=1 FOR UPDATE; one has to write SELECT person_id FROM person WHERE person_id=1 FOR UPDATE; | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2021-11-04 11:23 | MIT License | |
| 8 | FOR UPDATE is not needed if there is no FROM clause in the SELECT statement | Find routines that use SELECT … FOR UPDATE without selecting rows from a specific table. For instance: SELECT 'text' AS v FOR UPDATE; | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2021-11-05 14:10 | MIT License | |
| 9 | The use of xmin hidden column in views and routines | Find the number of views and materialized views that have a column with the xid type and the number of routines that contain a UPDATE or a DELETE statement that search condition refers to the xmin column. If one uses optimistic approach for dealing with the concurrent modifications of data, then xmin values should be presented by views and used in routines that modify or delete rows. | Sofware measure | INFORMATION_SCHEMA+system catalog base tables | 2021-11-04 11:56 | MIT License | |
| 10 | User-defined routines that use xmin hidden column | Find routines that contain a UPDATE or a DELETE statement that search condition refers to the xmin column. If one uses optimistic approach for dealing with the concurrent modifications of data, then xmin values should be presented by views and used in routines that modify or delete rows. | General | INFORMATION_SCHEMA+system catalog base tables | 2021-11-04 11:30 | MIT License | |