Goal Find base table columns with CHAR(n) or VARCHAR(n) type and make sure that n is not too big or too small. Also make sure that you do not use CHAR(n) in case of columns that have to keep variable length strings. "Values of type character are physically padded with spaces to the specified width n, and are stored and displayed that way" (https://www.postgresql.org/docs/current/datatype-character.html)
Notes Query returns also information about columns that properties have been specified through a domain.
Type General (Overview of some aspect of the database.)
License MIT (opens in new tab)
Fixing Suggestion Change the field size. If the column is specified through a domain, then you have to create a new domain and associate the column with the new domain because you cannot change the field size with the ALTER DOMAIN statement.
Data Source INFORMATION_SCHEMA only
SQL Query 
SELECT table_schema, table_name, column_name, data_type, character_maximum_length
FROM INFORMATION_SCHEMA.columns
WHERE data_type LIKE '%char%' AND character_maximum_length IS NOT NULL AND
(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)
ORDER BY data_type, character_maximum_length DESC, table_schema, table_name, ordinal_position;

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Find problems by overview

Queries that results point to different aspects of database that might have problems. A human reviewer has to decide based on the results as to whether there are problems or not .

NameDescription
Find problems by overviewQueries that results point to different aspects of database that might have problems. A human reviewer has to decide based on the results as to whether there are problems or not .

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Data types

Queries of this category provide information about the data types and their usage.

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Data typesQueries of this category provide information about the data types and their usage.