Am 01/18/2017 um 05:54 AM schrieb Neslisah Demirci: > Hi , > > > I have problem about this issue ; > > > could not serialize access due to read/write dependencies among transactions That's something you have to expect when using SERIALIZABLE isolation level. Maybe re-read https://www.postgresql.org/docs/current/static/transaction-iso.html#XACT-SERIALIZABLE > A message app like whatsapp i decided to use isolation level > serializable if i use other transaction levels many conversations > started with same number (think about whatsapp web sidebar multipling > with same number every message). Are you not using a sequence for generating these IDs? As those are counting independent of transaction visibility... What you say sounds more like "SELECT max(conversation_id) + 1 AS new_conversation_id FROM ..." > I also add an index to my query and my query's execution plan don't use > seq scan . > > > How can i solve this issue ? Can i solve this on db orr on app ? a) switch to a sequence for generating these IDs (you can go back to a lower isolation level then). You may get holes in the IDs then (on rolled back transactions), but I don't see how that would not be acceptable for conversation IDs b) deal with it in the app (probably not what you want, think roud-trip time) > Neslişah Demirci | Veritabanı Yöneticisi > > Ayazağa cad. No:4 Uniq İstanbul Plaza > B2 /Kat:3 34396 Ayazağa-SARIYER-İstanbul > T. (+90) 212 453 16 00 – 5516 > F. (+90) 212 453 16 16 > www.markafoni.com <http://www.markafoni.com/> > www.facebook.com/markafoni <http://www.facebook.com/markafoni> > blog.markafoni.com > > > Regards, -- Gunnar "Nick" Bluth DBA ELSTER Tel: +49 911/991-4665 Mobil: +49 172/8853339
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