Goal Find foreign key constraints that cover one column in case of which the name of refererenced/referencing column is in plural and the name of referencing/refererenced column is in singular.
Notes The query works somewhat correctly only if the names are in English. The query is based on a simplified assumption that in case of many words in English (of course, not all) the plural form is indicated by the letter "s" at the end of the word. If the name or its subcomponent ends with s and it is not preceded with an underscore and a single letter or a letter "s", then it is considered plural.
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)
Data Source INFORMATION_SCHEMA+system catalog
SQL Query
WITH columns AS (SELECT nspname AS table_schema, relname AS table_name, 
attname AS column_name,
CASE WHEN typbasetype=0 THEN pg_type.typname 
ELSE (SELECT typname 
FROM pg_type AS domain_type
WHERE domain_type.oid=pg_type.typbasetype) END AS column_type,
CASE WHEN attndims<>0 OR typndims<>0 THEN TRUE ELSE FALSE END AS is_array
FROM pg_class INNER JOIN pg_namespace ON pg_class.relnamespace=pg_namespace.oid
INNER JOIN pg_attribute ON pg_class.oid=pg_attribute.attrelid
INNER JOIN pg_type ON pg_attribute.atttypid =pg_type.oid
WHERE attnum>=1 
AND relkind ='r'
AND nspname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL)),
plural_singular AS (SELECT table_schema, table_name, column_name, 
CASE WHEN is_array=FALSE THEN column_type ELSE 'ARRAY [' || translate(column_type,'_','') || ']' END AS column_type, 
CASE WHEN regexp_replace(column_name,'(stats_|stats$|status|state|is_|has_|pos$|alias|cvs|address|value$|key$|pays$|group$|lock$|_to$|_id$|_code$|_type$|_name$|posts_to|sales_tax|trans_type|_date$|_time$|_flag$|number|sys|class$|basis$)','','g') ~* '(?<!((^|_)[[:alnum:]]{0,2}|(^|_)[bcdfghjklmnpqrsztvwxz]{0,4}|s))s(_|$)' THEN 'Perhaps plural' ELSE 'Perhaps singular' END AS comment_about_the_column_name
FROM columns),
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
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 cardinality(o.conkey)=1),
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
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, a_foreign.attname as foreign_col, target_schema, target_table, a_target.attname as target_col
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)
select conname, foreign_schema, foreign_table, foreign_col, psf.comment_about_the_column_name AS foreign_comment, 
target_schema, target_table, target_col, pst.comment_about_the_column_name AS target_comment
from fk_with_names AS fwn INNER JOIN plural_singular AS psf ON fwn.foreign_schema=psf.table_schema AND fwn.foreign_table=psf.table_name AND fwn.foreign_col=psf.column_name
INNER JOIN plural_singular AS pst ON fwn.target_schema=pst.table_schema AND fwn.target_table=pst.table_name AND fwn.target_col=pst.column_name
WHERE psf.comment_about_the_column_name<>pst.comment_about_the_column_name
order by target_schema, target_table, conname;

Categories

This query is classified under the following categories:

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.

NameDescription
InconsistenciesQueries of this catergory provide information about inconsistencies of solving the same problem in different places.
NamingQueries of this category provide information about the style of naming.