bito-code-review[bot] commented on PR #42203:
URL: https://github.com/apache/superset/pull/42203#issuecomment-5011939656
<!-- Bito Reply -->
The flagged performance issue is correct. Unconditionally calling
`list(data)` creates a full copy of the result set in memory, which can lead to
memory spikes or OOM errors for large queries. To resolve this, you should only
convert `data` to a list if it is not already a mutable sequence (e.g., if it
is a tuple).
Here is the proposed fix for `superset/db_engine_specs/base.py`:
```python
if column_mutators:
if not isinstance(data, list):
data = list(data)
indexes = {row[0]: idx for idx, row in
enumerate(description)}
```
This change ensures that if `fetchall()` already returns a list (as is
common with many DB drivers), the memory-intensive copy is avoided. I have
checked the other comments on this PR, and there are no other actionable review
comments to address. Would you like me to proceed with any other changes?
**superset/db_engine_specs/base.py**
```
if column_mutators:
if not isinstance(data, list):
data = list(data)
indexes = {row[0]: idx for idx, row in
enumerate(description)}
```
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