| Query goal: | Find the number of different character maximum lengths that are used to define textual base table columns as well as list all the different lengths. Show also the total number of columns with char/varchar type. Maximum character length constrains values in a column. Thus, in case there is a small number of used lengths, it raises a question as to whether the lengths have been optimally selected. |
| Query type: | Sofware measure (Numeric values (software measures) about the database) |
| Query license: | MIT License |
| Data source: | INFORMATION_SCHEMA only |
| SQL query: | Click on query to copy it
WITH lengths AS (SELECT DISTINCT character_maximum_length FROM INFORMATION_SCHEMA.columns INNER JOIN INFORMATION_SCHEMA.tables USING (table_schema, table_name) WHERE table_type='BASE TABLE' AND data_type ILIKE '%char%' 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)) SELECT Count(character_maximum_length) AS number_of_different_char_max_lengths, Count(*) AS number_of_char_varchar_columns, string_agg(character_maximum_length::text, ',<br>' ORDER BY character_maximum_length) AS character_maximum_lengths FROM lengths; |
| 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 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 . |
| Find quick numeric overview of the database | Queries that return numeric values showing mostly the number of different types of database objects in the database |
| Category name | Category description |
|---|---|
| Field size | Queries of this category provide information about the maximum size of values that can be recorded in column fields |