ResultProxy fetches don't wrap DBAPI exceptions

[sqlalchemy-bot]

Issue created by Anonymous

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I was using SQLALchemy 0.4.3 to read a simple Oracle table in an endless loop when I shut down the server (on purpose). Apparently this was noticed after the query was executed but during the fetches on the ResultProxy. The resulting cx_Oracle exception was not wrapped in a subclass of DBAPIError. The following code reproduces the problem reliably if you have the server up at the start then take it down before hitting Return.

import sys

from sqlalchemy import (create_engine, MetaData, Table, Column,
                        Integer, String)

engine = create_engine(sys.argv[1](1))
meta = MetaData(bind=engine)
example = Table("example",
                meta,
                Column("id", Integer, primary_key=True),
                Column("name", String(20))
                )
meta.drop_all()
meta.create_all()
example.insert().execute(id=1, name="George")
example.insert().execute(id=2, name="Ursula")
example.insert().execute(id=3, name="Ape")
example.insert().execute(id=4, name="Shep")
example.insert().execute(id=5, name="TookieTookie")

rows = example.select().execute()
raw_input("Type return when the server is down.")
print list(rows)

Type return when the server is down.
Traceback (most recent call last):
  File "sabug.py", line 23, in <module>
    print list(rows)
  File "/tmp/SQLAlchemy-0.4.3/lib/sqlalchemy/engine/base.py", line 1533, in __iter__
    row = self.fetchone()
  File "/tmp/SQLAlchemy-0.4.3/lib/sqlalchemy/engine/base.py", line 1633, in fetchone
    row = self._fetchone_impl()
  File "/tmp/SQLAlchemy-0.4.3/lib/sqlalchemy/engine/base.py", line 1608, in _fetchone_impl
    return self.cursor.fetchone()
cx_Oracle.DatabaseError: ORA-03113: end-of-file on communication channel

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Attachments: result_catches.patch

[sqlalchemy-bot]

Michael Bayer (zzzeek) wrote:

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Removing milestone: 0.4.6 (automated comment)

[sqlalchemy-bot]

Michael Bayer (zzzeek) wrote:

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going to leave 0.3 alone

[sqlalchemy-bot]

Michael Bayer (zzzeek) wrote:

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0.4 version is fixed in 47418e0f87cb432e0d813c7c30e43822fa479e9e

[sqlalchemy-bot]

Michael Bayer (zzzeek) wrote:

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er, 0.3 doesn't have the infrastructure needed for this in place; theres several other places the catch is needed including set_input_sizes(), which is used by oracle. The reconnect logic itself was also overhauled in 0.4 as it wasn't working that great in 0.3...so a backport from 0.4 into 0.3 would be a significant job. It would be less work overall if you could upgrade to 0.4, its a pretty easy upgrade path since you can move to 0.3.11, make your app forwards-compatible with 0.4, then move to 0.4.

[sqlalchemy-bot]

Michael Bayer (zzzeek) wrote:

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ive attached a patch for this, i was wondering can you just test this out with your particular setup ? I think we can probably add tests to test/engine/reconnect.py for this particular issue as well.

[sqlalchemy-bot]

Anonymous wrote:

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That works, thanks. By the way, I see the same thing in 0.3.6 so you may need to patch 0.3.11 as well.

[sqlalchemy-bot]

Changes by Michael Bayer (zzzeek): removed "0.4.6" milestone

[sqlalchemy-bot]

Changes by Michael Bayer (zzzeek): set state to "resolved"

[sqlalchemy-bot]

Changes by Michael Bayer (zzzeek): changed component from "(none)" to "sql"; set milestone to "0.4.4"