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);

Locating this inspection

By ID

Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.

SqlRedundantLimit

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Settings or Preferences | Editor | Inspections | SQL

Inspection Details
By default bundled with:	CLion 2024.3, DataGrip 2024.3, GoLand 2024.3, IntelliJ IDEA 2024.3, JetBrains Rider 2024.3, PhpStorm 2024.3, PyCharm 2024.3, Qodana for .NET 2024.3, Qodana for Go 2024.3, Qodana for JS 2024.3, Qodana for JVM 2024.3, Qodana for PHP 2024.3, Qodana for Ruby 2024.3, RubyMine 2024.3, WebStorm 2024.3
Can be installed with plugin:	Database Tools and SQL, 243.23140

Last modified: 03 December 2024