ruby on rails 4 - handling really long migrations in Heroku -

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how can speed long migrations (millions of rows, lots of moving stuff around)?

is there way run migration in concurrency, or script migration run in background , can promote it?

how can run long migrations without timing-out in heroku run rake console?

the bottleneck migration communication between client , server. best approach online (i.e. part of application or separate application sharing same database) , pull required resources in vie http.

alternatively - downtime - can create dump of database, manipulate locally on workstation , upload heroku restore database it. however, depending on data size, may take long , therefore not feasible.

when migrating data online, can migrate related parts on access, e.g. migrate data of single customer account next time customer accesses it. delay long, little message inform user of migration progress.


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