Find sets of columns that have both case sensitive and case insesitive unique constraints enforced based on these columns. In case of textual columns uniqueness could be checked either in case sensitive or case insensitive way. It is a contradiction to check the uniqueneness in both ways in case of the same key.
Notes
The query considers both unique indexes and exclusion constraints. The query only considers constraints/indexes that involve one column.
Type
Problem detection (Each row in the result could represent a flaw in the design)
Drop either the constraint that enforces case sensitive uniqueness or the unique index that enforces case insensitive uniqueness.
Data Source
INFORMATION_SCHEMA+system catalog
SQL Query
with idx AS (SELECT
n.nspname AS index_schema,
c.relname AS index_name,
c2.relname AS table_name,
i.indrelid AS index_table_oid,
unnest(indkey) AS index_col
FROM pg_catalog.pg_index AS i INNER JOIN pg_catalog.pg_class AS c ON i.indexrelid=c.oid
INNER JOIN pg_catalog.pg_class AS c2 ON i.indrelid=c2.oid
INNER JOIN pg_catalog.pg_namespace n ON c.relnamespace=n.oid
WHERE indisunique=true AND indnatts=1 AND nspname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL)),
idx_with_names as (select index_name, index_schema, table_name, a_idx.attname as column_name
from idx k inner join pg_attribute a_idx on k.index_col = a_idx.attnum and k.index_table_oid = a_idx.attrelid and a_idx.attisdropped = false
inner join pg_type t on a_idx.atttypid=t.oid
left join pg_type td on t.typbasetype=td.oid
where coalesce(td.typname, t.typname)='text' or coalesce(td.typname, t.typname) like '%char%'),
unique_function_based_indexes AS (SELECT schemaname, tablename, indexdef, indexname
FROM (SELECT schemaname, tablename, indexdef, indexname
FROM pg_catalog.pg_indexes
WHERE indexdef~*'unique[[:space:]]+index.+(upper|lower)[(]'
union select
(select nspname from pg_namespace where oid=c.relnamespace) as excl_schema,
c.relname as excl_table,
pg_get_indexdef(o.conindid) as index_def,
c2.relname as index_name
from pg_constraint o inner join pg_class c on c.oid = o.conrelid
inner join pg_class c2 on o.conindid=c2.oid
where o.contype in ('x')
and pg_get_indexdef(o.conindid) ~*'(upper|lower)') AS foo
WHERE schemaname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL))
SELECT index_schema, table_name, column_name, index_name as case_sensitive_index_name, p.indexname as case_insensitive_index_name, p.indexdef as case_insensitive_index_definition
FROM idx_with_names i, unique_function_based_indexes p
WHERE i.index_schema=p.schemaname
AND i.table_name=p.tablename
AND p.indexdef~*('[(].*'||i.column_name || '[)]')
ORDER BY index_schema, table_name, column_name;
SQL statements that help generate fixes for the identified problem.
SQL Query to Generate Fix
Description
with idx AS (SELECT
n.nspname AS index_schema,
c.relname AS index_name,
c2.relname AS table_name,
i.indrelid AS index_table_oid,
unnest(indkey) AS index_col
FROM pg_catalog.pg_index AS i INNER JOIN pg_catalog.pg_class AS c ON i.indexrelid=c.oid
INNER JOIN pg_catalog.pg_class AS c2 ON i.indrelid=c2.oid
INNER JOIN pg_catalog.pg_namespace n ON c.relnamespace=n.oid
WHERE indisunique=true AND indnatts=1 AND nspname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL)),
idx_with_names as (select index_name, index_schema, table_name, a_idx.attname as column_name
from idx k inner join pg_attribute a_idx on k.index_col = a_idx.attnum and k.index_table_oid = a_idx.attrelid and a_idx.attisdropped = false
inner join pg_type t on a_idx.atttypid=t.oid
left join pg_type td on t.typbasetype=td.oid
where coalesce(td.typname, t.typname)='text' or coalesce(td.typname, t.typname) like '%char%')
SELECT format('DROP INDEX %1$I.%2$I;', index_schema, p.indexname) AS statements
FROM idx_with_names i, pg_catalog.pg_indexes p
WHERE i.index_schema=p.schemaname AND i.table_name=p.tablename AND (p.indexdef LIKE '%(upper(%' || i.column_name || ')%' OR
p.indexdef LIKE '%(lower(%' || i.column_name || ')%')
ORDER BY index_schema, table_name, column_name;
Drop the case sensitive index.
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
Case sensitivity vs. case insensitivity
Queries of this category provide information about case sensitivity/insensitivity of identifiers or user data.
Performance
Queries of this category provide information about indexes in a database.
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).