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Message-ID: <65937bea0901060943w52c5473ucee1a90f36842d4c@mail.gmail.com>
Date: Tue, 6 Jan 2009 23:13:59 +0530
From: "Gurjeet Singh" <singh.gurjeet@gmail.com>
To: "Tom Lane" <tgl@sss.pgh.pa.us>
Subject: Re: [HACKERS] ERROR: failed to find conversion function from
	"unknown" to text
Cc: "Pavel Stehule" <pavel.stehule@gmail.com>,
	"PGSQL General" <pgsql-general@postgresql.org>,
	"PGSQL Hackers" <pgsql-hackers@postgresql.org>
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On Tue, Jan 6, 2009 at 7:18 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:

> "Gurjeet Singh" <singh.gurjeet@gmail.com> writes:
> >> This is a horrendously bad idea; it will bite your *ss sooner or later,
> >> probably sooner.
>
> > Can you please let us know how this would be problematic?
>
> The point is that it's going to have unknown, untested effects on the
> default coercion rules, possibly leading to silent changes in the
> behavior of queries that used to work.  If you'd rather retest every one
> of your other queries than fix this one, then go ahead.
>
>
Changing the query is an option not given to us. It is being migrated from a
BigDB.

I was working on these solutions assuming that these are workarounds to a
bug. But from your mails, it seems that it is an expected behaviour; is it?

If we consider the second branch of UNION ALL of both the queries above, if
"select '' " yields a text column, then so should a "select * from (select
'')".

Its not exactly a bug, but sure is a problem that we should try to resolve.

Thanks and best regards,
-- 
gurjeet[.singh]@EnterpriseDB.com
singh.gurjeet@{ gmail | hotmail | indiatimes | yahoo }.com

EnterpriseDB      http://www.enterprisedb.com

Mail sent from my BlackLaptop device

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On Tue, Jan 6, 2009 at 7:18 PM, Tom Lane <span dir="ltr">&lt;<a href="mailto:tgl@sss.pgh.pa.us">tgl@sss.pgh.pa.us</a>&gt;</span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div class="Ih2E3d">&quot;Gurjeet Singh&quot; &lt;<a href="mailto:singh.gurjeet@gmail.com">singh.gurjeet@gmail.com</a>&gt; writes:<br>
</div><div class="Ih2E3d">&gt;&gt; This is a horrendously bad idea; it will bite your *ss sooner or later,<br>
&gt;&gt; probably sooner.<br>
<br>
</div><div class="Ih2E3d">&gt; Can you please let us know how this would be problematic?<br>
<br>
</div>The point is that it&#39;s going to have unknown, untested effects on the<br>
default coercion rules, possibly leading to silent changes in the<br>
behavior of queries that used to work. &nbsp;If you&#39;d rather retest every one<br>
of your other queries than fix this one, then go ahead.<br>
<br>
 </blockquote></div><br>Changing the query is an option not given to us. It is being migrated from a BigDB.<br><br>I was working on these solutions assuming that these are workarounds to a bug. But from your mails, it seems that it is an expected behaviour; is it?<br>
<br>If we consider the second branch of UNION ALL of both the queries
above, if &quot;select &#39;&#39; &quot; yields a text column, then so should a &quot;select *
from (select &#39;&#39;)&quot;.<br clear="all"><br>Its not exactly a bug, but sure is a problem that we should try to resolve.<br><br>Thanks and best regards,<br>-- <br>gurjeet[.singh]@EnterpriseDB.com<br>singh.gurjeet@{ gmail | hotmail | indiatimes | yahoo }.com<br>
<br>EnterpriseDB &nbsp; &nbsp; &nbsp;<a href="http://www.enterprisedb.com">http://www.enterprisedb.com</a><br><br>Mail sent from my BlackLaptop device<br>

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