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Date: Wed, 30 May 2007 22:38:38 -0700
From: "Mamta Satoor" <msatoor@gmail.com>
To: derby-dev@db.apache.org
Subject: Re: more on system schema vs. user schema and character constants.
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Dan, I am trying to understand the difference between connection's current
schema vs compilation schema of a statement. It will help me a lot if you
could talk about the 2 schemas in reference to an example.

thanks,
Mamta


On 5/30/07, Daniel John Debrunner <djd@apache.org> wrote:
>
> Mike Matrigali wrote:
> > I am sort of confused at this point, what we expect to be working
> > now and what should be.  What is the right way to write the
> > following query against a the system schema?  Is there anyway to
> > write the query without changing the default schema? :
>
> Not sure if it's related or not but I just noticed this code in CastNode
> and there is other similar fragments elsewhere in ValueNodes.
>
>     //set the collation type to be same as the current schema's
>     //collation type. Collation derivation is already initialized
>     //to correct value by default which is "IMPLICIT"
>     getTypeServices().setCollationType(
>   getLanguageConnectionContext().getDefaultSchema().getCollationType());
>
> I think this is incorrect. During compilation the correct value to get
> the current schema is using the getSchemaDescriptor(null) call for any
> node. The current schema for compilation will not match the connection's
> current schema in some situations, such as compiling an action statement
> for a trigger, a sps for metadata queries and possibly for views as well.
>
> If this code is frequent it might be worth creating a utility method in
> ValueNode as
>
> setSchemaCollation() {
>     getTypeServices().setCollationType(
>      getSchemaDescriptor(null).getCollationType());
> }
>
> Dan.
>
>

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<div>Dan, I am trying to understand the difference between connection&#39;s current schema vs compilation schema of a statement. It will help me a lot if you could talk about the 2 schemas in reference to an example.</div>

<div>&nbsp;</div>
<div>thanks,</div>
<div>Mamta<br><br>&nbsp;</div>
<div><span class="gmail_quote">On 5/30/07, <b class="gmail_sendername">Daniel John Debrunner</b> &lt;<a href="mailto:djd@apache.org">djd@apache.org</a>&gt; wrote:</span>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">Mike Matrigali wrote:<br>&gt; I am sort of confused at this point, what we expect to be working<br>&gt; now and what should be.&nbsp;&nbsp;What is the right way to write the
<br>&gt; following query against a the system schema?&nbsp;&nbsp;Is there anyway to<br>&gt; write the query without changing the default schema? :<br><br>Not sure if it&#39;s related or not but I just noticed this code in CastNode<br>
and there is other similar fragments elsewhere in ValueNodes.<br><br>&nbsp;&nbsp;&nbsp;&nbsp;//set the collation type to be same as the current schema&#39;s<br>&nbsp;&nbsp;&nbsp;&nbsp;//collation type. Collation derivation is already initialized<br>&nbsp;&nbsp;&nbsp;&nbsp;//to correct value by default which is &quot;IMPLICIT&quot;
<br>&nbsp;&nbsp;&nbsp;&nbsp;getTypeServices().setCollationType(<br>&nbsp;&nbsp;getLanguageConnectionContext().getDefaultSchema().getCollationType());<br><br>I think this is incorrect. During compilation the correct value to get<br>the current schema is using the getSchemaDescriptor(null) call for any
<br>node. The current schema for compilation will not match the connection&#39;s<br>current schema in some situations, such as compiling an action statement<br>for a trigger, a sps for metadata queries and possibly for views as well.
<br><br>If this code is frequent it might be worth creating a utility method in<br>ValueNode as<br><br>setSchemaCollation() {<br>&nbsp;&nbsp;&nbsp;&nbsp;getTypeServices().setCollationType(<br>&nbsp;&nbsp;&nbsp;&nbsp; getSchemaDescriptor(null).getCollationType());
<br>}<br><br>Dan.<br><br></blockquote></div><br>

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