Goal Find cases where optional columns are before a mandatory column. Place mandatory columns before optional columns to improve comprehensibility of the table.
Notes M denotes a mandatory column and O an optional column. Columns are sorted based on the ordinal position.
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)
Fixing Suggestion Changing the order of columns in an existing table that is already in use requires dropping and re-creating the table and loading data to the new table. Probably this is not worth the trouble. Change the order only in case of newly create tables.
Data Source INFORMATION_SCHEMA only
SQL Query 
WITH nullability_pattern AS (SELECT table_schema, table_name, 
string_agg(CASE WHEN is_nullable='NO' THEN 'M' ELSE 'O' END,'' ORDER BY ordinal_position) AS pattern
FROM INFORMATION_SCHEMA.columns
WHERE (table_schema, table_name) IN (SELECT table_schema, table_name
FROM INFORMATION_SCHEMA.tables WHERE table_type='BASE TABLE') AND 
table_schema NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL)
GROUP BY table_schema, table_name)
SELECT table_schema, table_name, pattern
FROM nullability_pattern
WHERE pattern!~'^M+O*$'
ORDER BY table_schema, table_name;

Categories

This query is classified under the following categories:

Comfortability of database evolution

Queries of this category provide information about the means that influence database evolution.

Missing data

Queries of this category provide information about missing data (NULLs) in a database.

NameDescription
Comfortability of database evolutionQueries of this category provide information about the means that influence database evolution.
Missing dataQueries of this category provide information about missing data (NULLs) in a database.