Find base table primary key and unique constraints where all columns probably have a static default value. Candidate key columns (columns that belong to the primary key or to an unique constraints) shouldn't have static default values unless you are enforcing a rule that a table can have at most one row. The point of default values is that system assigns them automatically. There cannot be multiple rows with the same key value.
Notes
The query takes into account that the default value may be assigned to the column through a domain. 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.
Type
Problem detection (Each row in the result could represent a flaw in the design)
with keys as (select
o.conname,
(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.contype='p' then 'PRIMARY KEY'
else 'UNIQUE' end AS constraint_type
from pg_constraint o inner join pg_class c on c.oid = o.conrelid
where o.contype in ('u', 'p')),
keys_unnest as (select conname, target_schema, target_table, target_table_oid, target_col, target_col_num, ordin, constraint_type
from keys, unnest(keys. target_col) with ordinality as f(target_col_num, ordin)),
keys_with_names as (select conname, target_schema, target_table, array_agg(a_target.attname order by a_target.attname)::text[] as key_columns, constraint_type
from keys_unnest k inner join pg_attribute a_target on k.target_col_num = a_target.attnum and k.target_table_oid = a_target.attrelid and a_target.attisdropped = false
group by conname, target_schema, target_table, constraint_type),
def_columns AS (SELECT table_schema, table_name, c.column_name, coalesce(column_default, domain_default) AS def
FROM INFORMATION_SCHEMA.columns AS c LEFT JOIN INFORMATION_SCHEMA.domains AS d USING (domain_schema, domain_name)
WHERE coalesce(column_default, domain_default) IS NOT NULL),
def_columns_with_names AS (
SELECT table_schema, table_name, array_agg(column_name ORDER BY column_name)::text[] AS def_columns, string_agg(column_name || ' DEFAULT:' || def, '; ' ORDER BY column_name) AS def_columns_extended
FROM def_columns
WHERE def~*'^['']'
OR def~*'^(true|false)$'
OR def~*'^([[:digit:]]|[.])+$'
OR def~*'^[(]+([[:digit:]]|[.])+[)]+'
GROUP BY table_schema, table_name)
select d.table_schema, d.table_name, d.def_columns_extended as def_columns, k.key_columns, k.constraint_type
from def_columns_with_names as d, keys_with_names as k
where d.table_schema=k.target_schema and d.table_name=k.target_table and d.def_columns@>k.key_columns
order by target_schema, target_table;
SQL statements that help generate fixes for the identified problem.
SQL Query to Generate Fix
Description
with keys as (select
o.conname,
(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.contype='p' then 'PRIMARY KEY'
else 'UNIQUE' end AS constraint_type
from pg_constraint o inner join pg_class c on c.oid = o.conrelid
where o.contype in ('u', 'p')),
keys_unnest as (select conname, target_schema, target_table, target_table_oid, target_col, target_col_num, ordin, constraint_type
from keys, unnest(keys. target_col) with ordinality as f(target_col_num, ordin)),
keys_with_names as (select conname, target_schema, target_table, a_target.attname as key_column, constraint_type
from keys_unnest k inner join pg_attribute a_target on k.target_col_num = a_target.attnum and k.target_table_oid = a_target.attrelid and a_target.attisdropped = false),
def_columns AS (SELECT table_schema, table_name, c.column_name, d.domain_schema, d.domain_name
FROM INFORMATION_SCHEMA.columns AS c LEFT JOIN INFORMATION_SCHEMA.domains AS d USING (domain_schema, domain_name)
WHERE domain_default IS NOT NULL
AND (domain_default~*'^['']'
OR domain_default~*'^(true|false)$'
OR domain_default~*'^([[:digit:]]|[.])+$'
OR domain_default~*'^[(]+([[:digit:]]|[.])+[)]+'))
SELECT DISTINCT format('ALTER DOMAIN %1$I.%2$I DROP DEFAULT;', d.domain_schema, d.domain_name) AS statements
FROM def_columns as d INNER JOIN keys_with_names as k
ON d.table_schema=k.target_schema AND d.table_name=k.target_table AND d.column_name=k.key_column
ORDER BY statements;
Drop the default value associated with the domain.
with keys as (select
o.conname,
(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.contype='p' then 'PRIMARY KEY'
else 'UNIQUE' end AS constraint_type
from pg_constraint o inner join pg_class c on c.oid = o.conrelid
where o.contype in ('u', 'p')),
keys_unnest as (select conname, target_schema, target_table, target_table_oid, target_col, target_col_num, ordin, constraint_type
from keys, unnest(keys. target_col) with ordinality as f(target_col_num, ordin)),
keys_with_names as (select conname, target_schema, target_table, a_target.attname as key_column, constraint_type
from keys_unnest k inner join pg_attribute a_target on k.target_col_num = a_target.attnum and k.target_table_oid = a_target.attrelid and a_target.attisdropped = false),
def_columns AS (SELECT table_schema, table_name, c.column_name
FROM INFORMATION_SCHEMA.columns AS c
WHERE column_default IS NOT NULL
AND (column_default~*'^['']'
OR column_default~*'^(true|false)$'
OR column_default~*'^([[:digit:]]|[.])+$'
OR column_default~*'^[(]+([[:digit:]]|[.])+[)]+'))
SELECT format('ALTER TABLE %1$I.%2$I ALTER COLUMN %3$I DROP DEFAULT;', d.table_schema, d.table_name, d.column_name) AS statements
FROM def_columns as d INNER JOIN keys_with_names as k
ON d.table_schema=k.target_schema AND d.table_name=k.target_table AND d.column_name=k.key_column
ORDER BY d.table_schema, d.table_name, d.column_name;
Drop the default value associated with the column.
Collections
This query belongs to the following collections:
Name
Description
Find problems about integrity constraints
A selection of queries that return information about the state of integrity constraints in the datadabase. 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
This query is classified under the following categories:
Name
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.
Default value
Queries of this catergory provide information about the use of default values.
Fatal problems
Queries of this category provide information about problems that render a part of a database unusable.
Uniqueness
Queries of this category provide information about uniqueness constraints (PRIMARY KEY, UNIQUE, EXCLUDE) as well as unique indexes.
Validity and completeness
Queries of this category provide information about whether database design represents the world (domain) correctly (validity) and whether database design captures all the information about the world (domain) that is correct and relevant (completeness).