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Bulk Copy Handles Decimal Inconsistently Compared with Normal Queries #457

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Bulk Copy Handles Decimal Inconsistently Compared with Normal Queries#457
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Theekshna
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area: bulk-copyIssues in cursor.bulkcopy()triage neededFor new issues, not triaged yet.

Description

@amachanic
Adam Machanic (amachanic)
opened on Feb 27, 2026

Describe the bug

Trying to insert into a Decimal column with the new bulk_copy can throw an exception regarding mismatched decimal scale, whereas a normal insert will succeed and automatically deal with the issue. I would like to see bulk_copy work similarly and seamlessly.

To reproduce

import mssql_python
from decimal import Decimal

conn = mssql_python.connect([conn string], autocommit=True)
cur = conn.cursor()
cur.execute('create table dectest (d decimal(10, 2));')

# This next line works fine
cur.execute('insert into dectest values (?)', Decimal('123.456'))

# This line fails with the below exception
cur.bulkcopy('dectest', (Decimal('123.456'),))

Exception message

ValueError: Input decimal scale 3 exceeds target scale 2

Expected behavior

The bulkcopy should succeed and the value should be automatically rounded as it is in the insert.

Activity

  1. github-actions commented on Feb 27, 2026

    @github-actions
    github-actionsbot
    on Feb 27, 2026 – with GitHub Actions

    Hi Adam Machanic (@amachanic), thank you for opening this issue!

    Our team will review it shortly. We aim to triage all new issues within 24-48 hours and get back to you.

    If you have additional information to share, please feel free to update the issue.

    Thank you for your patience!

  2. github-actions
    added
    triage neededFor new issues, not triaged yet.
    on Feb 27, 2026

  3. saurabh500 commented on Feb 28, 2026

    @saurabh500
    Saurabh Singh (saurabh500)
    on Feb 28, 2026
    Contributor

    Thanks. We were conservative in conversions in bulkcopy for Decimal. The feedback makes sense. We can alleviate this restriction.

  4. ttk (Theekshna)
    self-assigned this
    on Mar 2, 2026
  5. Gaurav Sharma (bewithgaurav)
    added
    area: bulk-copyIssues in cursor.bulkcopy()
    on Jun 4, 2026

  6. amachanic commented on Aug 7, 2026

    @amachanic
    Adam Machanic (amachanic)
    on Aug 7, 2026
    Author

    Any updates here? Just hit this again today and had to work around. Kind of annoying. Would definitely appreciate a fix!

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