Potentially unnecessary use of sequence generators

Query goal:

Find simple natural key columns that are associated with a sequence generator.

Notes about the query:

The query considers both column names in English and Estonian. Thus, the query assumes that each natural key column has a prefix or suffix "kood" or "code". For instance, the name could be product_code or code_product. The query takes into account both external and internal (are created as the result of declaring a column as the identity column) sequence generators. The query takes into account a possibility that a column may be associated with a sequence generator through a domain.

Query type:

Problem detection (Each row in the result could represent a flaw in the design)

Query reliability:

Medium (Medium number of false-positive results)

Query license:

MIT License

Fixing suggestion:

Drop the column association with the sequence generator and the sequence generator itself. If the column values must be generated by the system, then rename the column (replace "kood" (in Estonian) or "code" with "id").

Data source:

INFORMATION_SCHEMA+system catalog

SQL query:

Click on query to copy it

with keys as (select 
(select nspname from pg_namespace where oid=c.relnamespace) as key_schema,
c.relname as key_table, 
c.oid as key_table_oid,
o.conkey AS key_col
from pg_constraint o inner join pg_class c on c.oid = o.conrelid
where o.contype in ('u', 'p') and cardinality(o.conkey)=1),
keys_unnest as (select key_schema, key_table, key_table_oid, key_col, key_col_num, ordin
from keys, unnest(keys.key_col) with ordinality as k(key_col_num, ordin)),
keys_with_names AS (select key_schema, key_table, a_key.attname as key_col
from keys_unnest k inner join pg_attribute a_key on k.key_col_num = a_key.attnum and k.key_table_oid = a_key.attrelid and a_key.attisdropped = false
),
fk as (select 
(select nspname from pg_namespace where oid=c.relnamespace) as key_schema,
c.relname as key_table, 
c.oid as key_table_oid,
o.conkey AS key_col
from pg_constraint o inner join pg_class c on c.oid = o.conrelid
where o.contype='f'),
fk_unnest as (select key_schema, key_table, key_table_oid, key_col, key_col_num, ordin
from fk, unnest(fk.key_col) with ordinality as k(key_col_num, ordin)),
fk_with_names AS (select key_schema, key_table, a_key.attname as key_col
from fk_unnest k inner join pg_attribute a_key on k.key_col_num = a_key.attnum and k.key_table_oid = a_key.attrelid and a_key.attisdropped = false),
key_not_fk AS (select key_schema, key_table, key_col
from keys_with_names
except select key_schema, key_table, key_col
from fk_with_names)
SELECT c.table_schema, c.table_name , c.column_name
FROM information_schema.columns c
LEFT JOIN information_schema.domains d USING (domain_schema, domain_name)
INNER JOIN information_schema.schemata s
ON c.table_schema=s.schema_name
WHERE  (coalesce (c.column_default, d.domain_default) ILIKE '%nextval%'  OR c.is_identity='YES')
AND (c.column_name~*'(code|kood)$' OR c.column_name~*'^(code|kood)_') 
AND (c.table_schema = 'public'
OR s.schema_owner<>'postgres')
AND EXISTS (SELECT *
FROM key_not_fk AS k
WHERE k.key_schema=c.table_schema
AND k.key_table=c.table_name
AND k.key_col=c.column_name)
ORDER BY table_schema, table_name;

Collections where the query belongs to

Collection name	Collection description
Find problems about base tables	A selection of queries that return information about the data types, field sizes, default values as well as general structure of base tables. Contains all the types of queries - problem detection, software measure, and general overview
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 .

Collection name

Collection description

Find problems about base tables

A selection of queries that return information about the data types, field sizes, default values as well as general structure of base tables. Contains all the types of queries - problem detection, software measure, and general overview

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 where the query belongs to

Category name	Category description
Comfortability of data management	Queries of this category provide information about the means that have been used to make the use or management of database more comfortable and thus, more efficient.
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.
Sequence generators	Queries of this category provide information about sequence generators and their usage.

Category name

Category description

Comfortability of data management

Queries of this category provide information about the means that have been used to make the use or management of database more comfortable and thus, more efficient.

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.

Sequence generators

Queries of this category provide information about sequence generators and their usage.