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About 50% slower in my synthetic scenario. The only difference is that (I guess) 2.4 relies on writeOps + GLE while 2.6 uses writeCmd (and so, in my test I didn't call GLE after remove() call). 2.6 testcase: db.dropDatabase(); var ndocs = 20000; for (var i = 0; i < ndocs; ++i) { db.foo.insert({"a": i}); } db.foo.ensureIndex({"a": 1}); var before = new Date().getTime(); for (var i = 0; i < ndocs; ++i) { db.foo.remove({"a": i}); } print(new Date().getTime() - before); 2.6 results (githash ad91eb0f75f39c1bb71b5e0ca4279b883cb9fe8d ): $ for i in `seq 1 5`; do ./mongo remove-26.js |grep ^[0-9]; done 4941 4937 4952 4932 4936 2.4 testcase: db.dropDatabase(); var ndocs = 20000; for (var i = 0; i < ndocs; ++i) { db.foo.insert({"a": i}); } db.foo.ensureIndex({"a": 1}); var before = new Date().getTime(); for (var i = 0; i < ndocs; ++i) { db.foo.remove({"a": i}); db.getLastError(); } print(new Date().getTime() - before); 2.4 results: $ for i in `seq 1 5`; do ./mongo remove-24.js |grep ^[0-9]; done 2782 2741 2737 2751 2755

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greg_10gen commented on Thu, 1 May 2014 16:14:34 +0000: Resolving as "Javascript write commands are slooow" greg_10gen commented on Mon, 7 Apr 2014 14:06:29 +0000: > Apparently the shell is awfully slow at building the commands, unless I'm missing something. Maybe the title of this ticket should be rephrased to reflect this new problem (if you consider this a problem). Yeah, it is - I'm not sure we care that much for now? No one should really be using the shell underneath an application - and if doing a lot of writes the batching should amortize the costs. David mentioned that he still saw regressions using the python driver - wonder if this is due to the same overhead. Ideally we could keep investigating, but IMO this is lower priority than more realistic write command tests. davide.italiano commented on Fri, 4 Apr 2014 23:47:08 +0000: I tested with the C and C++ driver to confirm it was a client-side issue rather than a server side issue, code attached. WriteOps results (against a 2.6 mongod): $ for i in `seq 1 5`; do ./writeops; done8.398115 8.288431 8.303667 8.308958 8.307844 WriteOps results (against a 2.4 mongod): $ for i in `seq 1 5`; do ./writeops; done 8.767040 8.767775 8.882403 8.768063 8.681774 WriteCmd results (against a 2.6 mongod): $ for i in `seq 1 5`; do ./writecmd; done 8.177082 8.157141 8.243254 8.213866 8.207350 The numbers do not show any evident regression in the new write path actually, and 2.6 is slightly faster than 2.4 in this scenario. Back to the Javascript shell I changed the script in this ticket to manually writing write commands instead of using the remove() helper in this way. db.runCommand({"delete": "foo", "deletes" : [{ "q": {"a": i}, "limit" : 0} ]}); instead of db.foo.remove({"a": i}); Results (hand-rolled write commands): $ for i in `seq 1 5`; do ./mongo remove-26.js | grep ^[0-9]; done 3045 3052 3064 3015 3107 Results(helper): for i in `seq 1 5`; do ./mongo remove-26.js | grep ^[0-9]; done 4945 4942 4900 4914 4956 Apparently the shell is awfully slow at building the commands, unless I'm missing something. Maybe the title of this ticket should be rephrased to reflect this new problem (if you consider this a problem).

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