Inspectopedia Help

Redundant row limiting in queries

Reports redundant row limiting clauses like FETCH and LIMIT in queries.

Example (PostgreSQL):

CREATE TABLE foo(a INT); SELECT * FROM foo WHERE EXISTS(SELECT * FROM foo LIMIT 2); SELECT * FROM foo WHERE EXISTS(SELECT * FROM foo FETCH FIRST 2 ROWS ONLY);

To fix the warning, you can add OFFSET to limiting clauses. If OFFSET is missing, then LIMIT is redundant because the usage of LIMIT does not influence the operation result of EXISTS. In case with OFFSET, we skip first N rows and this will influence the output.

SELECT * FROM foo WHERE EXISTS(SELECT * FROM foo OFFSET 1 ROW LIMIT 2); SELECT * FROM foo WHERE EXISTS(SELECT * FROM foo OFFSET 1 ROW FETCH FIRST 2 ROWS ONLY);

Inspection Details

Available in:

AppCode 2023.3, CLion 2023.3, DataGrip 2023.3, DataSpell 2023.3, GoLand 2023.3, IntelliJ IDEA 2023.3, JetBrains Rider 2023.1, PhpStorm 2023.3, PyCharm 2023.3, Qodana for .NET 2023.1, Qodana for JVM 2023.3, Qodana for PHP 2023.3, Qodana for Ruby 2023.3, RubyMine 2023.3

Plugin:

Database Tools and SQL, 233.SNAPSHOT

Last modified: 13 July 2023