Prefer UNION over UNION ALL

WarningPerformance & Database#EC PREF_UNIONRemote Enabled

Overview

Prefer UNION over UNION ALL in SQL queries.

ATC Finding Message: Prefer UNION over UNION ALL in SQL queries

Rationale

In ABAP SQL queries, prefer UNION to prevent duplicate record processing unless duplicates are explicitly intended and handled.

Non-Compliant

SELECT a FROM ztab1 UNION ALL SELECT a FROM ztab2 INTO TABLE @lt_data.

Compliant

SELECT a FROM ztab1 UNION SELECT a FROM ztab2 INTO TABLE @lt_data.

Suppression

To suppress findings for this rule, append the pseudo-comment to the statement:

" Standard pseudo-comment:
... "#EC PREF_UNION

" SAP CI_ prefix format:
... "#EC CI_PREF_UNION

Related Rules

• Prefer an Explicit JOIN Type — #EC PREF_JOIN_TYPE
• Prefer Strict SQL Host Variable Escaping — #EC PREF_STRICT_SQL

Technical Details

• Native ATC Class: ZCL_SKYLINT_PREF_UNION
• Implementation File: zcl_skylint_pref_union.clas.abap