intercepting WAL writes - Mailing list pgsql-hackers

From Mike
Subject intercepting WAL writes
Date
Msg-id 004a01c8c118$28b07d10$7a117730$@com
Whole thread Raw
Responses Re: intercepting WAL writes  ("Jonah H. Harris" <jonah.harris@gmail.com>)
Re: intercepting WAL writes  (Jeff Davis <pgsql@j-davis.com>)
Re: intercepting WAL writes  (Hannu Krosing <hannu@krosing.net>)
Re: intercepting WAL writes  (Mario Weilguni <mweilguni@sime.com>)
List pgsql-hackers
<div class="Section1"><p class="MsoNormal"><span style="font-size:10.0pt">Hello,</span><p class="MsoNormal"><span
style="font-size:10.0pt"> </span><pclass="MsoNormal"><span style="font-size:10.0pt">I’m new to the core PostgreSQL
code,so pardon the question if the answer is really obvious, and I’m just missing it, but I’ve got a relatively large
webapplication that uses PostgreSQL as a back-end database, and we’re heavily using memcached to cache frequently
accesseddata.</span><p class="MsoNormal"><span style="font-size:10.0pt"> </span><p class="MsoNormal"><span
style="font-size:10.0pt">I’mlooking at modifying PostgreSQL (in some way) to push changes directly to our memcache
servers,in hopes of moving towards a system where only writes are actually sent to the databases, and reads are
exclusivelysent to the memcache servers.</span><p class="MsoNormal"><span style="font-size:10.0pt"> </span><p
class="MsoNormal"><spanstyle="font-size:10.0pt">I’m guessing that I could intercept the WAL writes, and use this
informationto push out to my memcache servers, similar to a replication model.</span><p class="MsoNormal"><span
style="font-size:10.0pt"> </span><pclass="MsoNormal"><span style="font-size:10.0pt">Can somebody point to the most
logicalplace in the code to intercept the WAL writes? (just a rough direction would be enough)- or if this doesn’t make
senseat all, another suggestion on where to get the data? (I’m trying to avoid doing it using triggers).</span><p
class="MsoNormal"><spanstyle="font-size:10.0pt"> </span><p class="MsoNormal"><span
style="font-size:10.0pt">Thanks,</span><pclass="MsoNormal"><span style="font-size:10.0pt"> </span><p
class="MsoNormal"><spanstyle="font-size:10.0pt">Mike</span></div> 

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