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Optimize Collector to fetch only required fields for delete

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Avoids loading unnecessary or problematic data (e.g., invalid Unicode in text fields) during cascaded .delete(), improving performance and preventing decode errors.

Helps resolve UnicodeDecodeError seen in data purging (#21961).
This commit is contained in:
utkarsh.arya@zomato.com 2025-11-15 22:56:58 +00:00
parent 8180ffba21
commit a608c06cdb
1 changed files with 12 additions and 1 deletions
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13
django/db/models/deletion.py
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@ -232,9 +232,20 @@ class Collector:
"""
Get a QuerySet of objects related to `objs` via the relation `related`.
"""
return related.related_model._base_manager.using(self.using).filter(
qs = related.related_model._base_manager.using(self.using).filter(
**{"%s__in" % related.field.name: objs}
)
# Fetch only the fields needed for deletion to avoid loading
# potentially problematic data (e.g., invalid Unicode in text fields):
# - Primary key (for deletion SQL and sorting)
# - Foreign key fields (for signals, parent cascade, and field updates)
model = related.related_model
fields = [model._meta.pk.name]
# Add all foreign key fields (including parent links)
for field in model._meta.concrete_fields:
if field.many_to_one and field.name != model._meta.pk.name:
fields.append(field.name)
return qs.only(*fields)
def instances_with_model(self):
for model, instances in self.data.items():