Fwd: What do these terms mean in the SOURCE CODE?

<br />Is no one ready to help on this? :(<br /><br />-Vaibhav <br /><div class="gmail_quote">---------- Forwarded
message----------<br />From: <b class="gmail_sendername">Vaibhav Kaushal</b> <span dir="ltr"><<a
href="mailto:vaibhavkaushal123@gmail.com">vaibhavkaushal123@gmail.com</a>></span><br/> Date: Fri, Nov 19, 2010 at
9:11PM<br />Subject: What do these terms mean in the SOURCE CODE?<br />To: <a
href="mailto:pgsql-hackers@postgresql.org">pgsql-hackers@postgresql.org</a><br/><br /><br />I am going through the
Executorcode and come across the following terms quite often. Can someone tell me what do they mean (in a few (may be a
coupleof) sentences)?<br /><br />1. Scan State<br />2. Plan State<br />3. Tuple Projection<br /> 4. EState<br />5.
Qual<br/>6. Expression<br /><br />They sound quite ambiguous in the source code, specially when some of them already
haveterms which have multiple meanings. <br /><br />Thanks for your time. <br /><font color="#888888"><br /> -Vaibhav
(*_*)<br/></font></div><br />