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From: shashi B savarn <[email protected]>
To: [email protected]
Subject: Intermittent hang in SQLConnect (ODBC, PostgreSQL 15, Windows)
Date: Mon, 22 Jun 2026 13:49:19 +0530
Message-ID: <CA+4uE8JyjKfGuZP2c_XDtxdd6O65q+RHDJRr5=Q6UOHcRLErVg@mail.gmail.com> (raw)

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Hi all,

We are encountering an intermittent issue where our Windows-based
application hangs indefinitely during SQLConnect when connecting to a
PostgreSQL server via ODBC.
Environment

   - PostgreSQL version:  15.0.15.25315
   - ODBC driver: psqlODBC 16.00.0007
   - Connection type: ODBC using certificate-based authentication
   - Deployment: Application and PostgreSQL server both run on the same
   machine (localhost)

Application Behavior

   - The application maintains:
      - Some long-lived persistent connections
      - A few short-lived connections (3=E2=80=934) that are opened/closed
      periodically
   - Connection pooling is enabled (we also tested with pooling disabled
   and reduced timeouts=E2=80=94no change)

Configuration

   - Connection timeout is explicitly set before calling SQLConnect
   - TCP keepalive parameters are configured
   - Both settings are visible in PostgreSQL ODBC trace logs

Issue Description

On a subset of systems, intermittently (roughly once a week, sometimes more
frequently), the SQLConnect call:

   - Hangs indefinitely
   - Does not return or timeout

Observations / Troubleshooting

   - Initially suspected Microsoft Defender or network filtering:
      - Added PostgreSQL data directory to exclusions =E2=86=92 no improvem=
ent
      - No network filtering/firewall issues observed
   - Adjusted connection pooling and timeout values =E2=86=92 no impact

Call Stack During Hang

mswsock!WSPStartup
mswsock!WSPStartup
ws2_32!select
libpq!PQsocketPoll
libpq!PQsocketPoll
libpq!PQgetResult
psqlodbc35w!Ordinal94
psqlodbc35w!Ordinal94
psqlodbc35w!Ordinal94
psqlodbc35w!SQLConnectW
odbc32!SQLConnectW
odbc32!ODBCSetTryWaitValue
comsvcs!DispManGetContext
comsvcs!DispManGetContext
odbc32!SQLDriverConnectW
odbc32!SQLDriverConnectW
odbc32!SQLFreeStmt
odbc32!SQLConnectW
odbc32!SQLConnect

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