Tickets :: Comment on [#13876] horde_histories

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Comment	> Hi, > > This week I noticed my devices were not syncing data, and I've found > this in my logs: > 2015-02-16T11:50:35+01:00 ERR: HORDE [kronolith] SQL QUERY FAILED: > SQLSTATE[23505]: Unique violation: 7 ERROR: duplicate key violates > unique constraint "horde_histories_modseq_pkey" > INSERT INTO horde_histories_modseq (history_modseqempty) > VALUES(0) [pid 30578 on line 553 of > "/var/www/html/php/horde5-pear/pear/php/Horde/Db/Adapter/Base.php"] > 2015-02-16T11:50:35+01:00 ERR: HORDE [kronolith] SQLSTATE[23505]: > Unique violation: 7 ERROR: duplicate key violates unique constraint > "horde_histories_modseq_pkey" [pid 30578 on line 354 of > "/var/www/html/php/horde5-pear/pear/php/Horde/History/Sql.php"] > > Searching in my database (postgresql), I've found at > "horde_histories" table that "history_modseq" was reset to 1 > precisely at that timestamp. By that time, my server was heavy loaded. > So that "INSERT" error reset "history_modseq" sequence and my devices > requests are no longer able to find new events, contacts, etc. > > I took a look at code, trying to find out why that sequence was > reset. I have no answer yet, as I can't reproduce that event. > But I've found something rather odd in "Db/Adapter/Pdo/Pgsql.php" at > "insert" function: after every insert at database, primary keys are > recalculated calling resetPkSequence. I can't understand why you need > to do that. > And the problem is that resetPkSequence operates in a way that will > lead to "duplicate key violation" errors with sequences, as pointed > by the example in this post: > http://www.postgresql.org/message-id/4E5D8369.9090205@ringerc.id.au > Calling 'setval' that way while other processes may be calling > 'nextval' will generate the above errors. > > Getting a modseq reset is really something to avoid, also when heavy loaded. > > Thank you. >
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