Linux openSUSE Tumbleweed connection to MariaDB stopped working with version 5.x.x about pyodbc HOT 12 OPEN

An ODBC trace will be more useful to compare the differences.

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FWIW, the strace outputs show no evidence of pyodbc loading shared objects from different locations with v4 vs v5.

Also, this code works fine under Ubuntu 22.04 with pyodbc 5.1.0 and MariaDB Connector/ODBC v3.1.15 so pyodbc_5 does not have a problem with libmaodbc per se.

import pyodbc

print(pyodbc.version)
# 5.1.0

cnxn = pyodbc.connect(
    "Driver=MariaDB Unicode;"
    "Server=192.168.0.199;"
    "UID=scott;"
    "PWD=tiger;"
    "Database=test;"
)
print(cnxn.getinfo(pyodbc.SQL_DRIVER_NAME))
# libmaodbc.so
print(cnxn.getinfo(pyodbc.SQL_DRIVER_VER))
# 03.01.0015
crsr = cnxn.cursor()
print(crsr.execute("select version()").fetchval())
# 10.5.5-MariaDB-1:10.5.5+maria~focal

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I've created some ODBC traces for both pyodbc versions:

pyodbc_5.1.0_odbctrace.log
pyodbc_4.0.39_odbctrace.log

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Aha. So in both cases pyodbc calls SQLDriverConnectW which returns SQL_ERROR. pyodbc_4 immediately calls SQLDriverConnect which succeeds. pyodbc_5 calls SQLGetDiagRecW which returns SQL_NO_DATA. I don't know for sure if SQLGetDiagRecW returning SQL_NO_DATA translates into a 'The driver did not supply an error!' exception, but it seems plausible.

It appears that pyodbc_4 did not worry too much about SQLDriverConnectW failing and just soldiered on with SQLDriverConnect, while pyodbc_5 tries to find out why SQLDriverConnectW failed. Maybe pyodbc_5 just needs behave like pyodbc_4 in this particular case.

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@dhamonex - Do you get the error with pyodbc_5 if you use

conn = pyodbc.connect(
    connection_string,
    ansi=True
)

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I'm getting the same error as before, I've also attached the ODBC trace for ansi=True:

pyodbc_5.1.0_ansi_odbctrace.log

from pyodbc.

Okay, thanks. It looks like 5c1f1c0 completely removed the ansi flag, so it doesn't do anything any more. 🤷

I've tried a couple of older "ANSI" drivers (MySQL and PostgreSQL) but they seem to be okay with SQLDriverConnectW so I don't really know if this is a deficiency of that particular MariaDB driver or is something that pyodbc_5 should be able to handle. (Given the idiosyncrasies of all the ODBC drivers out there I would hope for the latter, but I'm not really qualified to say.)

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@v-chojas - Does the ODBC spec say anything about drivers returning SQL_ERROR for SQLDriverConnectW if they simply do not "do" Unicode?

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If the driver doesn't have the W functions the DM should do the narrowing conversion and then call the A function of the driver if the application calls the W function of the DM. However there has been a history of bugs around that part, especially in the DM and confusion between character and byte counts for length parameters. There may also be drivers that have both A and W functions, but one of them doesn't work. What version of unixodbc is the OP using?

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What version of unixodbc is the OP using?

@dhamonex - You could ask your package manager or use the odbcinst -j command to check.

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Tumbleweed is using unixODBC 2.3.12 the applied patches can be viewed here: https://build.opensuse.org/package/show/openSUSE%3AFactory/unixODBC

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FWIW the same problem occurs on Debian Bullseye, which ships odbc-mariadb version 3.1.9 and unixodbc version 2.3.6

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