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<p>Hi David,</p>
<p>This is a good example. I have modified this to walk networks
before, and it's a minimal and understandable example:</p>
<p><a class="moz-txt-link-freetext" href="http://blog.cleverelephant.ca/2010/07/network-walking-in-postgis.html">http://blog.cleverelephant.ca/2010/07/network-walking-in-postgis.html</a></p>
<p>There may be some better ways to do this, as the postgres tooling
has changed quite a bit. The use of a function may be precluded by
some modern fancy join type. Others can speak better to that than
I can these days.<br>
</p>
<p>Also, if you don't mind installing one more thing, pgrouting will
do network traversal much more efficiently than a <i>WITH
RECURSIVE</i> network traversal:</p>
<p><a class="moz-txt-link-freetext" href="https://pgrouting.org/">https://pgrouting.org/</a></p>
<p><br>
</p>
<p>Cheers,</p>
<p>Best,</p>
<p>Steve<br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 12/30/21 4:13 PM, Shaozhong SHI
wrote:<br>
</div>
<blockquote type="cite" cite="mid:CA+i5JwbGovfaVhYNGwdTXN6PUNnDA9F_SS5+i99v1HHwyZ_CAQ@mail.gmail.com">
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<div dir="ltr">In hydrological network, how to trace network from
each source node and check whether the trace can reach the sea?
<div><br>
</div>
<div>Any examples?</div>
<div><br>
</div>
<div>Regards,</div>
<div><br>
</div>
<div>David</div>
</div>
<br>
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