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<p class="MsoPlainText"><span lang="EN-US">Hi pgpool hackers,<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">I found the following SQL will be cached, when enabled memory query cache,
<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US"> "with cte as (insert into test2 values(1) returning *) select * from test2;"<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">I think the SQL has Data-Modifying Statements in with clause should not be cached.<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">Because Once cached, the Data-Modifying Statements will not be executed again which is not expected.<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">It seems to be better to analyze the with clause like the following:<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">--------For UPDATE/INSERT/DELETE type SQL:<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US"> extract oids from its with clause which will be invalidated.<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">--------For SELECT type SQL:<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US"> If Data-Modifying Statements in its with clause, the select will not be cached,<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US"> and the oids from with clause will be invalidated too.<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">What do you think?<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">I try to solve the problem and made a patch for the code.<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">Best regards,<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">houzj<o:p></o:p></span></p>
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