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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Hi Roy<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">You can certainly deadlock on a sequence and a table across to sessions accessing them in the reverse order. Is that what you meant?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Alex<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">S1:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">create sequence myseq \g<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">create table test as select reltid from iirelation \p\g<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">commit; \g<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">update test set reltid = reltid + 1 \g<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">S2:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">SELECT myseq.nextval AS mynextval; \g<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">S1:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">SELECT myseq.nextval AS mynextval;\g<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">S2:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">update test set reltid = reltid + 1 \g<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">S2 drops out with deadlock. Using “set lock_trace” you can see the locks taken by the nextval statements.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> info-ingres-bounces@lists.planetingres.org <info-ingres-bounces@lists.planetingres.org>
<b>On Behalf Of </b>Roy Hann<br>
<b>Sent:</b> 06 March 2018 11:49<br>
<b>To:</b> info-ingres@lists.planetingres.org<br>
<b>Subject:</b> [Info-ingres] Deadlock on a sequence<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Is it possible to get a resource deadlock on a sequence? For example:<br>
<br>
SELECT myseq.nextval AS mynextval;<br>
<br>
If it is, how could one go about inducing a deadlock?<br>
<br>
--Roy<br>
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