| Query goal: | Find the names of table CHECK constraints that have the same Boolean expression but a different naming style in different places (tables). The naming of constraints should be consistent. "If you do something a certain way, do all similar things in the same way." (Robert C. Martin, Clean Code) |
| Notes about the query: | The query constructs patterns of constraint names by replacing the table name with the word TABLE and column name with the word COLUMN. The query only considers CHECK constraints that are associated with a base table and that restrict values in exactly one column. The query only considers constraints that have the same syntax. The same rule could be enforced by different CHECK constraint Boolean expressions. The names of such constraints should follow the same pattern but the query does not check that. In case of the string_agg function, the line break (br) tag is used as a part of the separator for the better readability in case the query result is displayed in a web browser. |
| Query type: | Problem detection (Each row in the result could represent a flaw in the design) |
| Query reliability: | High (Few or no false-positive results) |
| Query license: | MIT License |
| Fixing suggestion: | Rename constraints to follow the same naming pattern. Pay attention that in PostgreSQL maximum identifier length is 63 bytes, i.e., in some places one has, for instance, to shorten the name. |
| Data source: | system catalog only |
| SQL query: | Click on query to copy it
WITH chk_constraint_names AS (select n.nspname as table_schema, c.relname as table_name, (select a.attname from pg_attribute a where a.attrelid = c.oid and a.attnum = o.conkey[1] and a.attisdropped = false) as column_name, o.conname AS constraint_name, substring(pg_get_constraintdef(o.oid),7) AS consrc from pg_constraint o inner join pg_class c on c.oid = o.conrelid inner join pg_namespace n on o.connamespace=n.oid where o.contype = 'c' and cardinality(o.conkey)=1), chk_constraint_names_generalized AS ( SELECT table_schema, table_name, column_name, replace(consrc, column_name,'VALUE') AS consrc, constraint_name AS constraint_name_original, CASE WHEN lower(table_name) ILIKE '%' || lower(column_name) || '%' THEN replace(replace(lower(constraint_name), lower(table_name), 'T A B L E'), lower(column_name),'C O L U M N') ELSE replace(replace(lower(constraint_name), lower(column_name), 'C O L U M N'), lower(table_name),'T A B L E') END AS constraint_name FROM chk_constraint_names) SELECT consrc, Count(DISTINCT constraint_name) AS cnt_different, Count(constraint_name) AS cnt_total, string_agg(DISTINCT constraint_name, ';<br>' ORDER BY constraint_name DESC) as name_different, string_agg('<b>' || table_schema || '.' || table_name || '</b> ' || constraint_name || ' (' || constraint_name_original || ')', ';<br>' ORDER BY constraint_name DESC) as name_all FROM chk_constraint_names_generalized GROUP BY consrc HAVING Count(DISTINCT constraint_name)>1 ORDER BY Count(DISTINCT constraint_name) DESC; |
| Collection name | Collection 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 . |
| Category name | Category description |
|---|---|
| CHECK constraints | Queries of this category provide information about CHECK constraints. |
| Inconsistencies | Queries of this catergory provide information about inconsistencies of solving the same problem in different places. |
| Naming | Queries of this category provide information about the style of naming. |
| Reference |
|---|
| The corresponding code smell in case of cleaning code is "G11: Inconsistency". (Robert C. Martin, Clean Code) |