Sophie: freetds-doc-0.91-8.mga5 x86

freetds-doc-0.91-8.mga5.x86_64.rpm

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><H1
><A
NAME="TROUBLESHOOTING"
></A
>Chapter 8. Troubleshooting</H1
><TABLE
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><TD
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>&nbsp;</TD
><TD
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><I
><P
><I
>He's like motherf**king McGuiver, no he's better than McGuiver!</I
></P
></I
></TD
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><TR
><TD
WIDTH="45%"
>&nbsp;</TD
><TD
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><I
><SPAN
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>Jason Mewes (Mall Rats)</SPAN
></I
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><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
><A
HREF="troubleshooting.htm#KNOWNISSUES"
>Known Issues</A
></DT
><DT
><A
HREF="serverthere.htm"
>Is the server there?</A
></DT
><DT
><A
HREF="logging.htm"
>Logging</A
></DT
><DT
><A
HREF="pagenodata.htm"
>"Page contains no data"</A
></DT
><DT
><A
HREF="seemtooslow.htm"
>Slow connection or data retrieval</A
></DT
></DL
></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="KNOWNISSUES"
>Known Issues</A
></H1
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="KNOWN.PORTING"
>Porting Issues</A
></H2
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="KNOWN.DATES"
>Date Structures and Offsets</A
></H3
><P
>Microsoft and Sybase use different <SPAN
CLASS="SYSTEMITEM"
>DB-Library</SPAN
> date structures <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>and conventions</I
></SPAN
>.  Notably months can by [0,11] or [1,12].  Pay careful attention to the results of <CODE
CLASS="FUNCTION"
>dbdatecrack()</CODE
>.  </P
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="KNOWN.FLOAT"
>Floating Point</A
></H3
><P
>Precision may surprise you if you pay attention.  Microsoft's <SPAN
CLASS="SYSTEMITEM"
>DB-Library</SPAN
> promotes single-precision to double in <CODE
CLASS="FUNCTION"
>dbbind()</CODE
> by appending zeros; C promotes it to the nearest double.  <SPAN
CLASS="PRODUCTNAME"
>FreeTDS</SPAN
> relies on the C compiler.  </P
><P
>Math libraries vary, too.  If porting an application whose output uses functions such at <CODE
CLASS="FUNCTION"
>log(3)</CODE
>, expect differences in different implementations.  Perfectly consistent results between OSes will require the use of a single math library.  </P
></DIV
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="TEXTFIELDS"
><SPAN
CLASS="TYPE"
>Text</SPAN
> Fields</A
></H2
><P
>Questions sometimes arise over large <SPAN
CLASS="TYPE"
>varchar</SPAN
> types (anything larger than <SPAN
CLASS="TYPE"
>varchar(255)</SPAN
>) that became available with Microsoft <SPAN
CLASS="PRODUCTNAME"
>SQL Server 7.0</SPAN
>.  When accessing long <SPAN
CLASS="TYPE"
>varchar</SPAN
>s with <ACRONYM
CLASS="ACRONYM"
>TDS</ACRONYM
> protocol version 4.2 or 5.0, these fields will be truncated to 255 characters, due to limitations inherent in the protocol definition.  Your best bet in that case is to convert them to <SPAN
CLASS="TYPE"
>text</SPAN
> types.</P
><P
>In Microsoft <SPAN
CLASS="PRODUCTNAME"
>SQL Server</SPAN
> 7.0 and later, <CODE
CLASS="STRUCTNAME"
>varchar</CODE
> types can hold up to 8000 bytes (8000 <ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
> characters or 4000 Unicode characters).  To move these large <CODE
CLASS="STRUCTNAME"
>varchar</CODE
>s through <ACRONYM
CLASS="ACRONYM"
>TDS</ACRONYM
> 4.2, convert them with either a <B
CLASS="COMMAND"
>CONVERT</B
> as in,
	<PRE
CLASS="SCREEN"
>	<KBD
CLASS="USERINPUT"
>SELECT mycol = convert(mycol, text) FROM mytable</KBD
> </PRE
>
	or with the newer SQL92 <B
CLASS="COMMAND"
>CAST</B
> syntax e.g.,
<PRE
CLASS="SCREEN"
>	<KBD
CLASS="USERINPUT"
>SELECT CAST(mycol as TEXT) FROM mytable</KBD
></PRE
></P
><P
>A related problem is that some people have reported problems with <SPAN
CLASS="TYPE"
>text</SPAN
> field using <ACRONYM
CLASS="ACRONYM"
>TDS</ACRONYM
> version 7.0.  One known workaround is to convert long strings to <SPAN
CLASS="TYPE"
>varchar(8000)</SPAN
> in your query text with <B
CLASS="COMMAND"
>CAST( <CODE
CLASS="PARAMETER"
>variable_name</CODE
> as <SPAN
CLASS="TYPE"
>varchar</SPAN
>(8000) ) as <CODE
CLASS="PARAMETER"
>variable_name</CODE
></B
>.  Text datatype handling is fixed in <SPAN
CLASS="PRODUCTNAME"
>FreeTDS</SPAN
> 0.60, except for bcp operations.</P
><P
>There is also a bug (<SPAN
CLASS="QUOTE"
>"Lions and tigers and bugs!  Oh, my!"</SPAN
>) in Microsoft's implementation of <SPAN
CLASS="TYPE"
>text</SPAN
> fields.  Disregardless [sic] of their documentation, you must explicitly set the value of <CODE
CLASS="ENVAR"
>TEXTSIZE</CODE
>, else the text fields will be represented to have a maximum size of 4 gigabytes or so.  The usual manifestation is some sort of spurious <SPAN
CLASS="QUOTE"
>"out of memory"</SPAN
> error or segment fault.  To avoid this, set <CODE
CLASS="ENVAR"
>TEXTSIZE</CODE
> to some reasonable value before querying any <SPAN
CLASS="TYPE"
>TEXT</SPAN
> fields.  For example, in <SPAN
CLASS="APPLICATION"
>isql</SPAN
>:
<PRE
CLASS="SCREEN"
>	<SAMP
CLASS="PROMPT"
>1&#62;</SAMP
><KBD
CLASS="USERINPUT"
>set <CODE
CLASS="ENVAR"
>TEXTSIZE</CODE
> 10000</KBD
>
	<SAMP
CLASS="PROMPT"
>2&#62;</SAMP
><KBD
CLASS="USERINPUT"
>go</KBD
></PRE
>
	
				Another way to handle control the default <CODE
CLASS="ENVAR"
>TEXTSIZE</CODE
> is to use the setting in <A
HREF="freetdsconf.htm#FREETDSCONFFORMAT"
><TT
CLASS="FILENAME"
>freetds.conf</TT
></A
>.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="ENDIANISM"
>Endianism</A
></H2
><P
>If either your server or your client is a big endian system, pay careful attention to all references to endianism anywhere near <SPAN
CLASS="PRODUCTNAME"
>FreeTDS</SPAN
>.  See the section on <A
HREF="configs.htm#EMULLE"
>Little Endian Emulation</A
> for details.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="DATETIME"
><SPAN
CLASS="TYPE"
>Datetime</SPAN
> and <SPAN
CLASS="TYPE"
>Money</SPAN
></A
></H2
><P
>Big endian clients may experience difficulty with Microsoft servers.  Some versions of <SPAN
CLASS="PRODUCTNAME"
>SQL Server</SPAN
> 7 did not handle these types on these machines correctly, according to the protocol.  According to
				<A
HREF="http://support.microsoft.com/support/kb/articles/Q254/1/23.ASP"
TARGET="_top"
> http://support.microsoft.com/support/kb/articles/Q254/1/23.ASP</A
> on the Microsoft support site, it's fixed as of service pack 3.  Unfortunately, there's no direct way for <SPAN
CLASS="PRODUCTNAME"
>FreeTDS</SPAN
> to know whether or not a service pack has been installed, and how/whether to support the buggy version is an outstanding issue.  Your best bet is to apply their patch.
				<DIV
CLASS="NOTE"
><P
></P
><TABLE
CLASS="NOTE"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="../images/note.gif"
HSPACE="5"
ALT="Note"></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>The Knowledge Base article states <SPAN
CLASS="QUOTE"
>"The Sybase CT-Lib client is the only known big-endian client that can connect to <SPAN
CLASS="PRODUCTNAME"
>SQL Server</SPAN
>."</SPAN
>  Depends on who's doing the knowing, of course.</P
></TD
></TR
></TABLE
></DIV
></P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="INTEGRATEDSECURITY"
>Microsoft's <SPAN
CLASS="QUOTE"
>"Integrated Security"</SPAN
></A
></H2
><P
><SPAN
CLASS="PRODUCTNAME"
>FreeTDS</SPAN
> may be unable to connect to the server.  The error message will be <SAMP
CLASS="COMPUTEROUTPUT"
>"Login failed for user 'example'.  Reason: Not associated with a trusted SQL Server connection"</SAMP
>.  To solve this, turn on <SPAN
CLASS="PRODUCTNAME"
>SQL Server</SPAN
> authentication:</P
><P
></P
><UL
><LI
><P
>Open the <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
><SPAN
CLASS="PRODUCTNAME"
>SQL Server</SPAN
> Enterprise Manager</I
></SPAN
>,</P
></LI
><LI
><P
>Select the server,</P
></LI
><LI
><P
>Right mouse click and choose <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>Properties</I
></SPAN
>.  A properties window will appear.</P
></LI
><LI
><P
>Choose the <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>Security</I
></SPAN
> tab.  The security properties will be displayed.</P
></LI
><LI
><P
>Change the <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>Authentication</I
></SPAN
> field to <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
><SPAN
CLASS="PRODUCTNAME"
>SQL Server</SPAN
> and Windows</I
></SPAN
>,</P
></LI
><LI
><P
>Apply the changes and try again.</P
></LI
></UL
><P
>These instructions apply to Microsoft <SPAN
CLASS="PRODUCTNAME"
>SQL Server 7</SPAN
> and <SPAN
CLASS="PRODUCTNAME"
>SQL Server 2000</SPAN
>.</P
><DIV
CLASS="NOTE"
><P
></P
><TABLE
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WIDTH="100%"
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><TD
WIDTH="25"
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><IMG
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HSPACE="5"
ALT="Note"></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
><SPAN
CLASS="PRODUCTNAME"
>FreeTDS</SPAN
> supports integrated security mode, too.  If you have <SPAN
CLASS="PRODUCTNAME"
>SQL Server</SPAN
> running in integrated (domain) mode along with a Windows PDC, and wish to try it, see <A
HREF="domains.htm"
>Domain Logins</A
> in the <A
HREF="configs.htm"
>Advanced Configurations</A
> chapter. If you have Active Directory you can also use Kerberos, see <A
HREF="kerberos.htm"
>Kerberos support</A
>.</P
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