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> User Guide: A Guide to Installing, Configuring, and Running <SPAN
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>FreeTDS</SPAN
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>Slow connection or data retrieval</A
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><P
><SPAN
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>FreeTDS</SPAN
> is <SPAN
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><I
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>not</I
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> slow.  We know this because we've tested it.  It's measurably slower than the vendors' products for some operations, but it's not noticeably slower and it's certainly no laggard.  If your experience is different, if you're waiting 30 seconds for simple operations or minutes instead of seconds for for query results, something is up with your setup.  There are two likely culprits.</P
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>Logging.  If everything seems a bit sluggish, check to make sure logging is turned off. <CODE
CLASS="ENVAR"
>TDSDUMP</CODE
> should not be defined, and there should be no <TT
CLASS="LITERAL"
>dump file</TT
>  mentioned in <TT
CLASS="FILENAME"
>freetds.conf</TT
>.  You can double-check by setting <CODE
CLASS="ENVAR"
>TDSDUMPCONFIG</CODE
> temporarily, which will log only the startup process.</P
></LI
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STYLE="list-style-type: disc"
><P
>DNS.  If connecting to the server takes 30 seconds or 1 minute, you could do worse than to check your <TT
CLASS="FILENAME"
>resolv.conf</TT
>.  Use <B
CLASS="COMMAND"
>host</B
> or <B
CLASS="COMMAND"
>nslookup</B
> to confirm that <SPAN
CLASS="PRODUCTNAME"
>FreeTDS</SPAN
> can actually resolve the name/address you provided in <TT
CLASS="FILENAME"
>freetds.conf</TT
>.  Give particular attention to reverse DNS lookups, if you were forced (or thought you were forced) to identify the server by number, instead of by name, as Vint intended.  You can defeat <SPAN
CLASS="PRODUCTNAME"
>FreeTDS</SPAN
>'s automatic reverse-DNS lookup feature by inserting
<PRE
CLASS="PROGRAMLISTING"
>	#define NOREVERSELOOKUPS
	</PRE
>

in <TT
CLASS="FILENAME"
>src/tds/config.c</TT
>, rebuilding, and reinstalling.

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> Reverse lookup code has been removed as of version 0.62 because it was poorly implemented.</P
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><P
>Packet size.  The default packet size setting in <TT
CLASS="FILENAME"
>freetds.conf</TT
> (see <TT
CLASS="LITERAL"
>initial block size</TT
>) is usually fine. Slowness can potentially be due to multiple packet to use.  Under <SPAN
CLASS="PRODUCTNAME"
><ACRONYM
CLASS="ACRONYM"
>GNU</ACRONYM
>/Linux</SPAN
> system we use an optimization to reduce network traffic; you shouldn't see much difference using this system.</P
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