NT + deadlock intended behaviour ? - Mailing list pgsql-hackers

From Gaetano Mendola
Subject NT + deadlock intended behaviour ?
Date
Msg-id 40F9B0FF.4060806@bigfoot.com
Whole thread Raw
Responses Re: NT + deadlock intended behaviour ?  (Alvaro Herrera <alvherre@dcc.uchile.cl>)
Re: NT + deadlock intended behaviour ?  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
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Hi all,
I'm doing some experiments with NT, I din't expect this behaviuor:


create table test ( a integer );
insert into test values (3);
insert into test values (4);
insert into test values (5);
insert into test values (6);



SESSION 1;                            SESSION 2;

begin;                              begin;
update test set a = 300 where a = 3;  update test set a = 40 where a = 4;
~                                      begin;
update test set a = 400 where a = 4;
<BLOCKED>
~                                      update test set a = 30 where a = 3;
~                                      <DEAD LOCK DETECTED>
~                                      commit;
<UNBLOCKED>    <-- !?!?!
~                      <here I'm able to do another commit>

why SESSION 1 was unblocked ? If I repeat again but I do an abort:



SESSION 1;                            SESSION 2;

begin;                              begin;
update test set a = 300 where a = 3;  update test set a = 40 where a = 4;
~                                      begin;
update test set a = 400 where a = 4;
<BLOCKED>
~                                      update test set a = 30 where a = 3;
~                                      <DEAD LOCK DETECTED>
~                                      abort;
<STILL BLOCKED>


Why that commit unblock the SESSION 1?


Regards
Gaetano Mendola








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