Scaling MongoDB at Mailbox
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Scaling MongoDB at Mailbox
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Re: Scaling MongoDB at Mailbox
#2Why has the new system less write lock? Is it sharded?
Re: Scaling MongoDB at Mailbox
#3>one performance issue that impacted us was MongoDB’s database-level write lock.
People give MSSQL shit for having row-level locks (if you don't use their MVCC option), yet how is it that Mongo runs with a database-wide option and people don't immediately laugh and walk away? Is the hype so powerful that people just shrug about a huge mutex?
Re: Scaling MongoDB at Mailbox
#4>one performance issue that impacted us was MongoDB’s database-level write lock. People give MSSQL shit for having row-level locks (if you don't use their MVCC option), yet how is it that Mongo runs with a database-wide option and people don't immediately laugh and walk away? Is the hype so powerful that people just shrug about a huge mutex?
The problems people encounter with SQL performance generally (or at least also) are on the read side where query optimization can become a pretty hard problem. Basically, the short answer is people are using SQL and noSQL very differently (as one would expect).
cue: someone telling me SQL query optimization is easy and people are just idiots.
Re: Scaling MongoDB at Mailbox
#5>one performance issue that impacted us was MongoDB’s database-level write lock. People give MSSQL shit for having row-level locks (if you don't use their MVCC option), yet how is it that Mongo runs with a database-wide option and people don't immediately laugh and walk away? Is the hype so powerful that people just shrug about a huge mutex?
MySQL has a few engines that still have a database level lock ( MyISAM, MEMORY ) and those generally preform better for unbalanced loads ( i.e very read heavy or very write heavy )
Re: Scaling MongoDB at Mailbox
#6I worked on a project where we used Mongo to collect analytics and while it worked, there were always problems. We had a problem with our shard key so one shard received more data which crashed it, overloaded the other two shards and crashed the whole system. A second issue we had was trying to read from Mongo while we were storing data which caused a lot of lock contention. The question I have is, knowing what you know now, would you have still gone with Mongo?
Re: Scaling MongoDB at Mailbox
#7>one performance issue that impacted us was MongoDB’s database-level write lock. People give MSSQL shit for having row-level locks (if you don't use their MVCC option), yet how is it that Mongo runs with a database-wide option and people don't immediately laugh and walk away? Is the hype so powerful that people just shrug about a huge mutex?
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Re: Scaling MongoDB at Mailbox
#8Why has the new system less write lock? Is it sharded?
It sounds like the new system is a cluster with a single collection. So all writes to the other collections no longer occur, therefore the write locks decreased
Re: Scaling MongoDB at Mailbox
#9Summary: vertical partition on collection. They wrote some new code to make moving a collection easier.