Re: Recursive Queries

Le jeudi 25 janvier 2007 à 12:12 -0500, Gregory Stark a écrit : <blockquote type="CITE"><pre>
<font color="#000000">"Joshua D. Drake" <<a href="mailto:jd@commandprompt.com">jd@commandprompt.com</a>>
writes:</font>

<font color="#000000">> > That's basically how the existing patch approached the problem. It invents a</font>
<font color="#000000">> > new type of join and a new type of tuplestore that behaves this way. This has</font>
<font color="#000000">> > the advantage of working the way Oracle users expect and being relatively</font>
<font color="#000000">> > simple conceptually. It has the disadvantage of locking us into what's</font>
<font color="#000000">> > basically a nested loop join and not reusing existing join code so it's quite</font>
<font color="#000000">> > a large patch.</font>
<font color="#000000">> </font>
<font color="#000000">> I believe our Syntax should be whatever the standard dictates,</font>
<font color="#000000">> regardless of Oracle.</font>

<font color="#000000">Well the issue here isn't one of syntax. The syntax is really an orthogonal</font>
<font color="#000000">issue. The basic question is whether to treat this as a new type of plan node</font>
<font color="#000000">with its behaviour hard coded or whether to try to reuse existing join types</font>
<font color="#000000">executing them recursively on their output. I can see advantages either way.</font>

<font color="#000000">As far as the syntax goes, now that I've actually read up on both, I have to</font>
<font color="#000000">say: I'm not entirely sure I'm happy IBM won this battle. The Oracle syntax is</font>
<font color="#000000">simple easy to use. The IBM/ANSI syntax is, well, baroque. There's a certain</font>
<font color="#000000">logical beauty to it but I can't see users being happy trying to figure out</font>
<font color="#000000">how to use it.</font>

</pre></blockquote><br /> I agree with THAT, it's clear that WITH RECURSIVE is more standard... but for the SQL
developperCONNECT BY is a paradise... the syntax is clear and powerful... That's why we've chosen to developp our
querieswith that (using the connectby() function and the <font size="1">evgen potemkin.</font>'s patch (<a
href="http://gppl.moonbone.ru/)">http://gppl.moonbone.ru/)</a><br/><br />
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