This query identifies foreign key relationships that are established using name columns rather than standard identifiers. In a well-designed database, relationships should be built upon stable natural keys (such as codes) or system-generated surrogate keys, rather than mutable textual names.
Type
Problem detection (Each row in the result could represent a flaw in the design)
To resolve this issue, refactor the database schema by replacing the name-based foreign key with a robust identifier. Ensure the referenced table has a proper primary key (either a natural code or a surrogate key). Add a corresponding referencing column to the dependent table, migrate the data, and recreate the foreign key constraint using these identifiers. Finally, remove the redundant name column from the dependent table to ensure proper normalization.
Data Source
system catalog only
SQL Query
WITH fk as (select
o.conname,
(select nspname from pg_namespace where oid=f.relnamespace) as foreign_schema,
f.relname as foreign_table,
f.oid as foreign_table_oid,
o.confkey AS foreign_col,
(select nspname from pg_namespace where oid=c.relnamespace) as target_schema,
c.relname as target_table,
c.oid as target_table_oid,
o.conkey AS target_col,
CASE WHEN o.confupdtype='a' THEN 'NO ACTION'
WHEN o.confupdtype='r' THEN 'RESTRICT'
WHEN o.confupdtype='c' THEN 'CASCADE'
WHEN o.confupdtype='n' THEN 'SET NULL'
WHEN o.confupdtype='d' THEN 'SET DEFAULT' END AS on_update,
CASE WHEN o.confdeltype='a' THEN 'NO ACTION'
WHEN o.confdeltype='r' THEN 'RESTRICT'
WHEN o.confdeltype='c' THEN 'CASCADE'
WHEN o.confdeltype='n' THEN 'SET NULL'
WHEN o.confdeltype='d' THEN 'SET DEFAULT' END AS on_delete
from pg_constraint o inner join pg_class c on c.oid = o.conrelid
inner join pg_class f on f.oid = o.confrelid
where o.contype = 'f'
and o.confupdtype<>'c'),
fk_unnest as (select conname, foreign_schema, foreign_table, foreign_table_oid, foreign_col, foreign_col_num, target_schema, target_table, target_table_oid, target_col, target_col_num, ordin, on_update, on_delete
from fk, unnest(fk.foreign_col, fk. target_col) with ordinality as f(foreign_col_num, target_col_num, ordin)),
fk_with_names as (select conname, foreign_schema, foreign_table, string_agg(a_foreign.attname, ',' order by ordin) as foreign_col, target_schema, target_table, string_agg(a_target.attname, ',' order by ordin) as target_col, on_update, on_delete
from fk_unnest fk inner join pg_attribute a_foreign on fk.foreign_col_num = a_foreign.attnum and fk.foreign_table_oid = a_foreign.attrelid and a_foreign.attisdropped = false
inner join pg_attribute a_target on fk.target_col_num = a_target.attnum and fk.target_table_oid = a_target.attrelid and a_target.attisdropped = false
group by conname, foreign_schema, foreign_table, target_schema, target_table,on_update, on_delete)
select conname, foreign_schema, foreign_table, foreign_col, target_schema, target_table, target_col, on_update, on_delete
from fk_with_names
WHERE foreign_col~*'(nimi|nimetus|name)'
OR target_col~*'(nimi|nimetus|name)'
order by target_schema, target_table, conname;
Collections
This query belongs to the following collections:
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:
Name
Description
Relationships between tables
Queries of this category provide information about how database tables are connected to each other and whether such connections have been explicitly defined and whether it has been done correctly.
Result quality depends on names
Queries of this category use names (for instance, column names) to try to guess the meaning of a database object. Thus, the goodness of names determines the number of false positive and false negative results.