Recently, we had an issue in our application which is a single
page application(SPA). We have all the functionality in a single
page and most of the data and view changes happen through ajax
requests and iframe page displays.We are using CodeIgniter
framework for this application. So sometimes what happened was
the user was logged out while accessing the application and this
occurred once a while for 1 or 2 users, not a reproducible case
one would say.Before starting on the case, I would like to
specify the steps which CodeIgniter takes for checking session
for any request.Steps:
1. Read session cookie sent from browser.
2. Read session cookie process proceeds with below step checks
(If any one step fails below, it results in create one session
cookie)
2a. Checks if session cookie is present
2b. Checks if it is a valid session cookie by using it's
decryption algorithm check
2c. If valid session, then check if …
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Percona’s CTO Vadim Tkachenko wrote a response to my Galera Snapshot Isolation post last week. I think Tkachenko may have misunderstood some of my results, and I’d like to clear those up now. I’ve ported the MariaDB tests to Percona XtraDB Cluster, and would like to confirm that using exclusive write locks on all reads, as Tkachenko recommends, can recover serializable histories. Finally, we’ll address Percona’s documentation.
I didn’t use the default isolation levels
But there I need to add quite IMPORTANT addition: it may leave data in inconsistent state if you use SPECIAL TYPE of transactions in default isolation levels that Aphyr uses in his test.
My tests did not use the default isolation …
[Read more]Percona’s CTO Vadim Tkachenko wrote a response to my Galera Snapshot Isolation post last week. I think Tkachenko may have misunderstood some of my results, and I’d like to clear those up now. I’ve ported the MariaDB tests to Percona XtraDB Cluster, and would like to confirm that using exclusive write locks on all reads, as Tkachenko recommends, can recover serializable histories. Finally, we’ll address Percona’s documentation.
I didn’t use the default isolation levels
But there I need to add quite IMPORTANT addition: it may leave data in inconsistent state if you use SPECIAL TYPE of transactions in default isolation levels that Aphyr uses in his test.
My tests did not use the default isolation …
[Read more]Percona’s CTO Vadim Tkachenko wrote a response to my Galera Snapshot Isolation post last week. I think Tkachenko may have misunderstood some of my results, and I’d like to clear those up now. I’ve ported the MariaDB tests to Percona XtraDB Cluster, and would like to confirm that using exclusive write locks on all reads, as Tkachenko recommends, can recover serializable histories. Finally, we’ll address Percona’s documentation.
I didn’t use the default isolation levels
But there I need to add quite IMPORTANT addition: it may leave data in inconsistent state if you use SPECIAL TYPE of transactions in default isolation levels that Aphyr uses in his test.
My tests did not use the default isolation …
[Read more]Facebook, with 1.49 billion monthly active users, is one of the world’s top MySQL users. Simon Martin, a production engineer on Facebook’s MySQL Infrastructure team, has been working with MySQL for most of his career, starting from 2 servers built out of spare parts and moving through to one of the largest deployments in the world.
Simon will be sharing some of the challenges Facebook has tackled as it rolled out semi-synchronous replication across the company’s different services at Percona Live Amsterdam on Sept. 22. His talk is aptly titled, “The highs and lows of semi-synchronous replication.” I sat down, virtually, with Simon the other day. Our conversation is below, but first, as a special reward to my readers, save €20 on your Percona Live registration by entering promo code …
[Read more]Previously, on Jepsen, we saw Chronos fail to run jobs after a network partition. In this post, we’ll see MariaDB Galera Cluster allow transactions to read partially committed state.
Galera Cluster extends MySQL (and MySQL’s fork, MariaDB) to clusters of machines, all of which support reads and writes. It uses a group communication system to broadcast writesets and certify each for use. Unlike most Postgres replication systems, it handles the failure and recovery of all nodes automatically, and unlike MySQL Cluster, it has only one (as opposed to three) types of node. The MariaDB Galera packages are particularly easy to install and configure.
Galera Cluster uses the normal InnoDB isolation levels …
[Read more]Previously, on Jepsen, we saw Chronos fail to run jobs after a network partition. In this post, we’ll see MariaDB Galera Cluster allow transactions to read partially committed state.
Galera Cluster extends MySQL (and MySQL’s fork, MariaDB) to clusters of machines, all of which support reads and writes. It uses a group communication system to broadcast writesets and certify each for use. Unlike most Postgres replication systems, it handles the failure and recovery of all nodes automatically, and unlike MySQL Cluster, it has only one (as opposed to three) types of node. The MariaDB Galera packages are particularly easy to install and configure.
Galera Cluster uses the normal InnoDB isolation levels …
[Read more]Previously, on Jepsen, we saw Chronos fail to run jobs after a network partition. In this post, we’ll see MariaDB Galera Cluster allow transactions to read partially committed state.
Galera Cluster extends MySQL (and MySQL’s fork, MariaDB) to clusters of machines, all of which support reads and writes. It uses a group communication system to broadcast writesets and certify each for use. Unlike most Postgres replication systems, it handles the failure and recovery of all nodes automatically, and unlike MySQL Cluster, it has only one (as opposed to three) types of node. The MariaDB Galera packages are particularly easy to install and configure.
Galera Cluster uses the normal InnoDB isolation levels …
[Read more]Auf der FrOSCon 10 in St. Augustin habe ich kürzlich ein Update zu unseren Erfahrungen mit dem Thema "Private Cloud mit OpenSource" gegeben. Leider sind noch nicht alle Probleme, über die letztes Jahr berichtet wurde, behoben, aber wir sind schon ein gutes Stück weiter und haben neue Stolperfallen gefunden und z. T. auch überwunden.
Leider habe ich mich mit der Zeit ein wenig getäuscht, da ich den Talk vorher schon einmal in gekürzter Form in 40 Minuten unterbringen musste, aber in der Präsentation den Countdown für die FrOSCon wieder auf 60 Minuten zu stellen vergessen hatte. Zwischenzeitlich war ich deswegen der Meinung, ziemlich hinterherzuhängen... Hoffe, es macht trotzdem ein bisschen Spaß, so blieb am Ende mehr Zeit für Fragen und Gespräche :)
Hier noch die Folien auf Slideshare:
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[Read more]