FIX: AV in Query with a Subselect on a View with a JOIN and FORCEPLAN Is On (176493)


The information in this article applies to:

  • Microsoft SQL Server 6.5
This article was previously published under Q176493
BUG #: 17418 (SQLBUG_65)

SYMPTOMS

A handled access violation (AV) may occur if all of the following conditions are true:

  • A query references a view.
  • The view contains a join.
  • The query contains a subselect.
  • SET FORCEPLAN ON was run before the query.
If all of these conditions are true, a DB-Library client may receive the following error:

DB-Library Process Dead - Connection Broken


An ODBC client may receive the following error:

[Microsoft][ODBC SQL Server Driver]Protocol error in TDS stream


You may see in the SQL Server error log messages similar to the following: 

   EXCEPTION_ACCESS_VIOLATION raised, attempting to create symptom dump
   Initializing symptom dump and stack dump facilities
   ***BEGIN STACK TRACE***
   0x0042F2C8 in sqlservr.EXE, newlinklock() + 0x0418
   0x00433717 in sqlservr.EXE, opendb() + 0x00F7
   0x0042ED45 in sqlservr.EXE, check_deadlock() + 0x0675
   0x0042EFA8 in sqlservr.EXE, newlinklock() + 0x00F8
   0x00423B50 in sqlservr.EXE, dbswriteflush() + 0x0160
   0x004229BD in sqlservr.EXE, dbswritecheck() + 0x07AD
   0x0040E680 in sqlservr.EXE, ksconsole() + 0x0320
   0x0040F1E5 in sqlservr.EXE, initcfgfix() + 0x03D5
   0x0040ED45 in sqlservr.EXE, initconfig() + 0x0165
   0x0040B7B2 in sqlservr.EXE, SqlDumpLocks() + 0x0052
   0x00415217 in sqlservr.EXE, udasyncwrite() + 0x0187

WORKAROUND

To work around this problem, do either of the following:
  • Do not use SET FORCEPLAN ON for the query.

    -or-
  • Change the query to avoid one of the other causes. For the most part, you can do this by using a join instead of a subselect.

STATUS

Microsoft has confirmed this to be a problem in SQL Server 6.5. This problem has been corrected in Service Pack 5a for Microsoft SQL Server 6.5.For more information, click the following article number to view the article in the Microsoft Knowledge Base:

197177 INF: How to Obtain SQL Server 6.5 Service Pack 5a

For more information, contact your primary support provider.

MORE INFORMATION

Steps to Reproduce the Problem

  1. Use the following to create the view:
    use pubs
go
create view v1 AS
select ta.title_id, t.pub_id
from titleauthor ta
inner join titles t on t.title_id = ta.title_id
  2. Use the following query to cause an access violation:
    set forceplan on
select distinct * from v1
where pub_id in (select pub_id from publishers)
set forceplan off


The following query demonstrates the workaround: 
set forceplan on
select distinct v1.* from v1
inner join publishers p on v1.pub_id=p.pub_id
set forceplan off
Modification Type:MajorLast Reviewed:3/14/2006
Keywords:kbBug kbfix kbusage KB176493
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