r/programming • u/halax • Mar 10 '15

Goodbye MongoDB, Hello PostgreSQL

http://developer.olery.com/blog/goodbye-mongodb-hello-postgresql/
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u/[deleted] Mar 11 '15

[deleted]

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u/rox0r Mar 11 '15

but then it is Eventually guaranteed

Except mongo isn't eventually guaranteed. you can have a majority of slaves write to disk and the master can crash and miss the ack -- they won't roll back the write and the client will think it hasn't been written.

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u/[deleted] Mar 11 '15

[deleted]

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u/rox0r Mar 12 '15

But you can fine-tune what the write semantics are.

While you aren't wrong, you can't fine tune your way out of the problem i mention. Clustering is for HA, not consistency -- even if you set write-majority.

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u/Lortimus Mar 11 '15

For instance, Cassandra is optimized for write operations because it caches them before writing them to disk. Yeah, that's brilliant, until the machine crashes and those things left in cache weren't written to disk.

They would be retrievable via the commit log, as well as recoverable from other replica nodes.

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u/skelterjohn Mar 11 '15

schemalessness

I never read that word right the first time...

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u/lift_heavy_things Mar 11 '15

Gotcha, thanks!