python.sqlalchemy.performance.performance-improvements.len-all-count

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Using QUERY.count() instead of len(QUERY.all()) sends less data to the client since the SQLAlchemy method is performed server-side.

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Defintion

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rules:
  - id: len-all-count
    pattern: len($X.all())
    message: Using QUERY.count() instead of len(QUERY.all()) sends less data to the
      client since the SQLAlchemy method is performed server-side.
    languages:
      - python
    severity: WARNING
    metadata:
      category: performance
      technology:
        - sqlalchemy
      license: Commons Clause License Condition v1.0[LGPL-2.1-only]

Examples

performance-improvements.py

# ruleid:batch-import
for song in songs:
    db.session.add(song)

# ruleid:len-all-count
len(persons.all())