| Goal | This query identifies user-defined routines that may be susceptible to concurrency anomalies due to a lack of explicit locking. PostgreSQL utilizes Multi-Version Concurrency Control (MVCC), where SELECT statements do not block data modification operations. Consequently, routines that read data to inform subsequent modifications without acquiring row-level locks (e.g., FOR UPDATE, FOR SHARE) or using isolation levels higher than READ COMMITTED are prone to race conditions. This query flags such routines for review to ensure transactional integrity is maintained. |
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| Notes | Refers to the column pg_proc.prokind and thus works starting from PostgreSQL 11. In the returned body of routine the query replaces each newline character with the line break (br) tag for the better readability in case the query result is displayed in a web browser. There could be multiple routines with the same name but with different parameters in the same schema (overloading). Thus, for the unique identification of the routine it is necessary to present also its parameters in addition to the schema name and routine name. The query assumes that explicit locking is needed if the routine reads data into a variable or in a subquery and as the result raises an exception or decides as to whether to modify data or not. |
| Type | Problem detection (Each row in the result could represent a flaw in the design) |
| Reliability | Low (Many false-positive results) |
| License | MIT (opens in new tab) |
| Fixing Suggestion | If needed use LOCK statement to lock the entire table or SELECT … FOR SHARE to lock specific rows. |
| Data Source | INFORMATION_SCHEMA+system catalog |
| SQL Query |
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Collections
This query belongs to the following collections:
Find problems automatically
Queries, that results point to problems in the database. Each query in the collection produces an initial assessment. However, a human reviewer has the final say as to whether there is a problem or not .
| Name | Description |
|---|---|
| Find problems automatically | Queries, that results point to problems in the database. Each query in the collection produces an initial assessment. However, a human reviewer has the final say as to whether there is a problem or not . |
Categories
This query is classified under the following categories:
Concurrency control
Queries of this category provide information about concurrency control.
Does not work in some earlier PostgreSQL version
Queries of this category provide information that was not available in some earlier PostgreSQL version
Transactions
Queries of this catergory provide information about the use of transactions.
User-defined routines
Queries of this category provide information about the user-defined routines
| Name | Description |
|---|---|
| Concurrency control | Queries of this category provide information about concurrency control. |
| Does not work in some earlier PostgreSQL version | Queries of this category provide information that was not available in some earlier PostgreSQL version |
| Transactions | Queries of this catergory provide information about the use of transactions. |
| User-defined routines | Queries of this category provide information about the user-defined routines |
Further reading and related materials: