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Severity: Warning

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Overview

The select-star rule flags the use of SELECT * in outermost queries. While convenient during development, SELECT * creates fragile code that can break when table schemas change. Rule name: select-star Default severity: Warning

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When This Rule Triggers

This rule triggers when:
  • SELECT * appears in the outermost query
  • SELECT * appears in either side of a UNION, INTERSECT, or EXCEPT operation at the top level
The rule does not trigger when:
  • Explicit column names are listed in the outermost query
  • SELECT * appears only inside a CTE (Common Table Expression)
  • SELECT * appears only in subqueries

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Why It Matters

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Schema Fragility

When you use SELECT *, your query implicitly depends on:
  1. The current order of columns in the table
  2. The current set of columns in the table
  3. The data types of all columns
If someone adds, removes, or reorders columns in the table, your application code may:
  • Receive columns in an unexpected order
  • Receive unexpected columns it doesn’t handle
  • Miss columns it expects
  • Experience type mismatches

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Performance Impact

Fetching all columns when you only need a few wastes:
  • Network bandwidth
  • Memory in your application
  • Database I/O and cache efficiency

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Maintenance Clarity

Explicit column lists make it clear what data the query actually needs, improving code readability and maintainability.

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Examples

SELECT * FROM users WHERE id = 1
Issue: The outermost query uses SELECT *, making it fragile to schema changes.
SELECT * FROM users UNION ALL SELECT * FROM admins
Issue: Both sides of the UNION use SELECT * in the outermost query.
WITH f AS (SELECT id FROM users) SELECT * FROM f
Issue: Even though the CTE uses explicit columns, the outer query uses SELECT *.
SELECT id, name FROM users
Why it’s better: Explicitly lists only the needed columns, making the query robust to schema changes.
WITH f AS (SELECT * FROM users) SELECT id, name FROM f
Why it’s allowed: The outermost query uses explicit columns, so the result set is stable even if SELECT * is used internally.

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Implementation Details

The rule works by:
  1. Identifying SELECT statements at the outermost level
  2. For set operations (UNION, INTERSECT, EXCEPT), checking both left and right queries
  3. Inspecting the target list for ColumnRef nodes with an A_Star field
  4. Reporting a warning at the location of each * found
Implementation: select_star.go

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How to Disable

You can disable this rule in your pgvet configuration: 
rules:
  select-star:
    enabled: false
Or disable it for specific queries using inline comments: 
-- pgvet: ignore select-star
SELECT * FROM users WHERE id = 1

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