Re:MongoDB 1.8 (stable) released
by JulianMorrison on Thursday March 17, 2011 @01:11PM
(#2336940)
Redis is for flat structures. MongoDB is for nested.
In both cases, (unlike CouchDB) you can alter data structures by more complex means than simply replacing the whole thing (such as incrementing a counter). In both (again unlike CouchDB) the updates overwrite in place and do not waste space (but also do not preserve past versions or allow readers to overlap writers).
Redis is for stuff that fits in memory. MongoDB scales up to "big data", provided the individual items are moderately sized.
Redis runs in RAM so it's blazingly fast. MongoDB is about as fast as MySQL.
Redis is single threaded so only one operation runs at once (the speed makes this mostly not a problem). Some operations globally block MongoDB, some can run in parallel.
In both, operations are atomic. Redis has transactions of a sort that group operations and ensure the data they relate to is unchanged. MongoDB operations can't be grouped into a transaction, but they can be a lot more complex so they effectively become a transaction (limited to operating on one data item).
In both cases, (unlike CouchDB) you can alter data structures by more complex means than simply replacing the whole thing (such as incrementing a counter). In both (again unlike CouchDB) the updates overwrite in place and do not waste space (but also do not preserve past versions or allow readers to overlap writers).
Redis is for stuff that fits in memory. MongoDB scales up to "big data", provided the individual items are moderately sized.
Redis runs in RAM so it's blazingly fast. MongoDB is about as fast as MySQL.
Redis is single threaded so only one operation runs at once (the speed makes this mostly not a problem). Some operations globally block MongoDB, some can run in parallel.
In both, operations are atomic. Redis has transactions of a sort that group operations and ensure the data they relate to is unchanged. MongoDB operations can't be grouped into a transaction, but they can be a lot more complex so they effectively become a transaction (limited to operating on one data item).