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Mixing Concat and Coalesce

Query goal: Find cases where different means are used to deal with NULLs in case of concatenating texsts.
Query type: Problem detection (Each row in the result could represent a flaw in the design)
Query reliability: Low (Many false-positive results)
Query license: MIT License
Fixing suggestion: Try to be consistent. Use concat(column1,column2) or coalesce(column1,'') || coalesce(column2,''). No need to mix the approaches in order to increase unnecessarily the complexity of code.
Data source: INFORMATION_SCHEMA+system catalog
SQL query: Click on query to copy it

WITH derived_tables AS (SELECT n.nspname AS schema_name, 
c.relname AS object_name,
CASE WHEN c.relkind='v' THEN 'VIEW'
WHEN c.relkind='m' THEN 'MATERIALIZED VIEW'
END AS object_type,
pg_get_viewdef(c.oid, true) AS object_definition,
regexp_replace(pg_get_viewdef(c.oid, true),'[\r\n]','<br>','g') AS object_def
FROM pg_namespace AS n INNER JOIN pg_authid AS a ON n.nspowner=a.oid
INNER JOIN pg_class AS c ON n.oid=c.relnamespace
WHERE (n.nspname='public' OR a.rolname<>'postgres')
AND relkind IN ('v','m')),
routines AS (SELECT 
  pg_namespace.nspname AS schema_name, 
  pg_proc.proname || '(' || pg_get_function_identity_arguments(pg_proc.oid) || ')' AS object_name,
  CASE WHEN pg_proc.prokind='f' THEN 'FUNCTION'
  WHEN pg_proc.prokind='p' THEN 'PROCEDURE'
  WHEN pg_proc.prokind='w' THEN 'WINDOW FUNCTION' END AS object_type,
  pg_get_functiondef(pg_proc.oid) AS object_definition,
  regexp_replace( regexp_replace(pg_get_functiondef(pg_proc.oid),'<','&lt','g'),'[\r\n]','<br>','g')  AS object_def
FROM 
  pg_catalog.pg_proc, 
  pg_catalog.pg_namespace
WHERE 
  pg_proc.pronamespace = pg_namespace.oid
 AND  pg_proc.prokind<>'a'
 AND pg_proc.proname NOT IN ('f_assume_you_must_use_files', 'f_check_format_comma_separated_list', 'f_check_password', 'f_default_value_with_no_match') AND
pg_namespace.nspname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL) 
AND NOT EXISTS (SELECT 1
FROM pg_catalog.pg_depend d 
WHERE EXISTS (SELECT 1 FROM pg_catalog.pg_extension e WHERE d.refobjid=e.oid) AND
d.objid=pg_proc.oid)),
checked_elements AS (SELECT schema_name, object_name, object_type, object_definition, object_def
FROM derived_tables
UNION SELECT schema_name, object_name, object_type, object_definition, object_def
FROM routines)
SELECT schema_name, object_name, object_type, object_def
FROM checked_elements
WHERE object_definition  ~*'[[:space:]](concat|concat_ws)[[:space:]]*[(].*[[:space:]]coalesce[[:space:]]*[(]'
ORDER BY schema_name, object_type, object_name;

Collections where the query belongs to

Collection nameCollection description
Find problems automaticallyQueries, 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 where the query belongs to

Category nameCategory description
Derived tablesQueries of this category provide information about the derived tables (views, materialized views), which are used to implement virtual data layer.
Does not work in some earlier PostgreSQL versionQueries of this category provide information that was not available in some earlier PostgreSQL version
Missing dataQueries of this category provide information about missing data (NULLs) in a database.
System-defined functionsQueries of this category provide information about the use of system-defined functions.
User-defined routinesQueries of this category provide information about the user-defined routines

The list of all the queries