Serialization errors in Postgres 9.4.0 - Mailing list pgsql-hackers

<div class="WordSection1"><p class="MsoNormal">Some time ago we upgraded from v. 8.4.4 to 9.4.0 and we are seeing
errorsin some regression tests.<p class="MsoNormal"> <p class="MsoNormal">LOCATION:  exec_simple_query,
postgres.c:887<pclass="MsoNormal">ERROR:  40001: could not serialize access due to read/write dependencies among
transactions<pclass="MsoNormal"> <p class="MsoNormal">Detail can be one of these: <p class="MsoNormal">   DETAIL: 
Reasoncode: Canceled on identification as a pivot, during commit attempt.<p class="MsoNormal">   DETAIL:  Reason code:
Canceledon identification as a pivot, during write.<p class="MsoNormal">   DETAIL:  Reason code: Canceled on
identificationas a pivot, during conflict out checking.<p class="MsoNormal"> <p class="MsoNormal">Location is usually
oneof these:<p class="MsoNormal">   LOCATION:  PreCommit_CheckForSerializationFailure, predicate.c:4654<p
class="MsoNormal">  LOCATION:  OnConflict_CheckForSerializationFailure, predicate.c:4600<p class="MsoNormal">  
LOCATION: CheckForSerializableConflictOut, predicate.c:3888<p class="MsoNormal"> <p class="MsoNormal">It may end up
with<pclass="MsoNormal">   ERROR:  25P02: current transaction is aborted, commands ignored until end of transaction
block<pclass="MsoNormal"> <p class="MsoNormal"> <p class="MsoNormal">The database at this point is likely to have a
barrageof read and write ops against few tables.<p class="MsoNormal">I understand that using serializable transaction
weprobably should be ready to retry, <p class="MsoNormal">but it would be helpful to understand why we did not see so
manyerrors in the past.<p class="MsoNormal"> <p class="MsoNormal">  Did something changed from 8.4.4 to 9.4.0?<p
class="MsoNormal"> Maybe Postgres has more aggressive predicate locking mechanism now?<p class="MsoNormal">  Can it be
thatbecause of the small table size it performs sequential scan and locks the entire table?<p class="MsoNormal"> <p
class="MsoNormal">Sorryif any of these questions are plain stupid.<p class="MsoNormal">Thanks,<p
class="MsoNormal">Michael.<pclass="MsoNormal"> <p class="MsoNormal"> <p class="MsoNormal"> </div><p style="FONT-SIZE:
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