DOCUMENT:Q216318 20-JUL-2000 [foxpro] TITLE :FIX: Slow Performance of Remote Views w/ SQL Server Text Fields PRODUCT :Microsoft FoxPro PROD/VER:WINDOWS:2.5,2.6,3.0,3.0b,5.0,5.0a,6.0 OPER/SYS: KEYWORDS:kbDatabase kbvfp kbvfp600 kbvfp600bug KbDBFDBC kbVS600sp3fix kbGrpDSFox kbGrpDSMDAC kbD ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a, 6.0 - Microsoft Data Access Components versions 2.5, 2.6 ------------------------------------------------------------------------------- SYMPTOMS ======== Application performance gradually degrades when inserting records into a remote view of a Microsoft SQL Server table containing text fields. The performance degradation becomes more evident as the table grows in size. CAUSE ===== With the 3.60 version of the Microsoft SQL Server ODBC driver (SQLSVR32.DLL), INSERTing data into remote views of SQL Server tables that contain one or more text fields initiates a table scan on the server. With SQL Server ODBC driver (SQLSRV32.DLL) version 3.70 and later, INSERTing data into remote views of SQL Server tables that contain one or more text fields initiates a table scan on the server under the following conditions: - A connection is being made to SQL Server 6.5. - The compatibility level of the driver has been set to SQL Server 6.5. RESOLUTION ========== This issue has been addressed in Visual Studio 6.0 Service Pack 3. For earlier versions of Visual FoxPro, depending on the version of SQL Server that is being accessed, there are multiple workarounds for this problem: - If connecting to SQL Server 7.0, use SQL Server ODBC Driver (version 3.70 or later) set to SQL Server 7.0 compatibility mode. - If connecting to SQL Server 6.5, use one of the 2.xx.xxxx versions of the SQL Server ODBC Driver. - Use SQL Pass Through as shown here: lcConnStr="DRIVER={SQL Server};SERVER=My_Server;DATABASE=PUBS;UID=sa;PWD=" gnConnHandle=SQLSTRINGCONN(lcConnStr) IF gnConnHandle>0 m.starting_value=SECONDS() for i=1 to 2000 SQLCommand="Insert into test_1 values ('"+ ; ALLTRIM(STR(i))+"','"+REPLICATE('ABCDE ',10)+"')" test=SQLEXEC(gnConnHandle,SQLCommand) IF test < 0 then AERROR(myerr) DISP MEMO LIKE myerr RETURN ENDIF NEXT m.ending_value=SECONDS() ? m.ending_value-m.starting_value =SQLDISCONN(gnConnHandle) ENDIF - Use an ADO RecordSet as shown here: lcConnStr="DRIVER={SQL Server};SERVER=My_Server;DATABASE=PUBS;UID=sa;PWD=" oConnection=CREATEOBJECT("ADODB.Connection") oConnection.ConnectionString = lcConnStr oConnection.CursorLocation = 3 oConnection.OPEN lcSQL="select * from test_1" rs=CREATEOBJECT("ADODB.Recordset") rs.activeconnection = oConnection rs.CursorLocation = 3 rs.cursortype = 1 rs.LockType = 3 rs.OPEN(lcSQL) m.starting_value=SECONDS() for i=1 to 2000 rs.addnew rs.FIELDS(0).VALUE=ALLTRIM(STR(i)) rs.FIELDS(1).VALUE=REPLICATE('ABCDE ',10) rs.UPDATE NEXT m.ending_value=SECONDS() ? m.ending_value-m.starting_value rs.CLOSE STATUS ====== This bug was corrected in Visual Studio 6.0 Service Pack 3. For more information about Visual Studio service packs, please see the following articles in the Microsoft Knowledge Base: Q194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why Q194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed MORE INFORMATION ================ Steps to Reproduce Behavior --------------------------- 1. If using SQLSRV32.DLL version 3.70 or later, set the compatibility level of the SQL Server ODBC driver for Visual FoxPro to 6.5 compatibility mode. 2. Create a program file named Testsql.prg using the following code: NOTE: This program creates a new SQL Server table in the database that the DSN specifies as the default and necessitates appropriate permissions. SET SAFETY OFF SET EXCLUSIVE ON SET MULTILOCKS ON gnConnHandle=SQLCONNECT('MYDSN','sa','') =sqltables(gnConnHandle,'TABLE') SELECT SQLRESULT IsFound=.F. LOCA SCAN FOR UPPER(ALLTRIM(TABLE_NAME))="TEST_1" IsFound=.T. EXIT ENDSCAN IF IsFound SQLCommand="DELETE FROM TEST_1" ELSE SQLCommand="CREATE TABLE TEST_1 (VAR1 CHAR(10) NULL, VAR2 TEXT NULL)" ENDIF testval=SQLEXEC(gnConnHandle,SQLCommand) CREATE DATABASE testa && CREATE a DATABASE CREATE CONNECTION test1 CONNSTRING "DRIVER={SQL Server};" + ; "SERVER=MY_SERVER;DATABASE=PUBS;UID=sa;PWD=" CREATE SQL VIEW testb REMOTE CONNECTION test1 ; AS SELECT * FROM dbo.test_1 test_1 =DBSETPROP('TEST1','Connection','DispLogin', 3) =DBSETPROP('TEST1','Connection','Asynchronous', .T.) =DBSETPROP('TEST1','Connection','DispWarnings', .T.) =DBSETPROP('TEST1','Connection','BatchMode', .F.) =DBSETPROP('TEST1','Connection','Transactions', 2) =DBSETPROP('TEST1','Connection','PacketSize',8192) =DBSETPROP('TEST1','Connection','Comment', 'Comment Added') =DBSETPROP('TEST1','Connection','ConnectTimeOut', 10) =DBSETPROP('TEST1','Connection','IdleTimeOut', 0) =DBSETPROP('TEST1','Connection','QueryTimeOut', 0) =DBSETPROP('TEST1','Connection','WaitTime',100) =DBSETPROP("TESTB",'View','SendUpdates',.T.) =DBSETPROP("TESTB",'View','UpdateType',1) =DBSETPROP("TESTB",'View','WhereType',3) =DBSETPROP("TESTB",'View','BatchUpdateCount',1) =DBSETPROP("TESTB",'View','UseMemoSize',255) =DBSETPROP("TESTB",'View','FetchSize',100) =DBSETPROP("TESTB",'View','FetchMemo',.T.) =DBSETPROP("TESTB",'View','MaxRecords',-1) =DBSETPROP("TESTB",'View','Tables','dbo.test_1') =DBSETPROP("TESTB",'View','Prepared',.T.) =DBSETPROP("TESTB",'View','CompareMemo',.T.) =DBSETPROP("TESTB",'View','FetchAsNeeded',.F.) USE testb =AFIELDS(viewflds) FOR i=1 TO ALEN(viewflds,1) fld_name=viewflds[i,1] viewfield=ALLTRIM("TESTB")+"."+ALLTRIM(fld_name) IF i=1 =DBSETPROP(viewfield,'Field','KeyField',.T.) ELSE =DBSETPROP(viewfield,'Field','KeyField',.F.) ENDIF =DBSETPROP(viewfield,'Field','Updatable',.T.) update_field="dbo.test_1."+alltrim(fld_name) =DBSETPROP(viewfield,'Field','UpdateName',update_field) NEXT m.starting_value=SECONDS() FOR i=1 TO 2000 INSERT INTO testb VALUES ; (ALLTRIM(STR(RECCOUNT()+1)), ; REPLICATE('ABCDE ',10)) NEXT m.ending_value=SECONDS() ? m.ending_value-m.starting_value CLOSE ALL =SQLDISCONN(gnConnHandle) CLEAR ALL RETURN 3. Run the program file and note the elapsed time. 4. Run the SQL Pass Through code from above and note the elapsed time. 5. Run the ADO sample code from above and note the elapsed time. 6. If using SQLSRV32.DLL version 3.70 or later, reset the compatibility level of the SQL Server ODBC driver for Visual FoxPro to the original value. (c) Microsoft Corporation 1999, All Rights Reserved. Contributions by John Desch, Microsoft Corporation. REFERENCES ========== For additional information setting the compatibility level of the SQL Server ODBC Driver for a specific application, click the article number below to view the article in the Microsoft Knowledge Base: Q231812 HOWTO: Programmatically Set the Compatibility Level of the SQL Server ODBC Driver For additional information restoring the compatibility level of the SQL Server ODBC Driver to SQL 7.0 compatibility for a specific application, click the article number below to view the article in the Microsoft Knowledge Base: Q233539 HOWTO: Programmatically Reset the Compatibility Level Setting of SQL Server ODBC Driver Version 3.70 Additional query words: ====================================================================== Keywords : kbDatabase kbvfp kbvfp600 kbvfp600bug KbDBFDBC kbVS600sp3fix kbGrpDSFox kbGrpDSMDAC kbDSupport kbMDAC250 kbMDAC260 Technology : kbVFPsearch kbAudDeveloper kbMDACSearch kbMDAC250 kbMDAC260 kbVFP300 kbVFP300b kbVFP500 kbVFP600 kbVFP500a Version : WINDOWS:2.5,2.6,3.0,3.0b,5.0,5.0a,6.0 Issue type : kbbug Solution Type : kbfix ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2000.