The idea is that you improve the performance of aggregation queries by using MapReduce on a sharded database that is distributed over multiple machines. I did some comparisons of the performance of Mongo’s Mapreduce with a group-by-select statement in Oracle on the same machine. I did find that Mongo was approximately 25 times slower. This … Read more
This is a great question. First of all, here are a couple of workarounds that come to mind (they all require changes to the query): First workaround This one maybe a bit obvious and unfortunately not generally applicable: If the selection of items you would need to pass over to Enumerable.Contains already exists in a … Read more
SET is the ANSI standard way of assigning values to variables, and SELECT is not. But you can use SELECT to assign values to more than one variable at a time. SET allows you to assign data to only one variable at a time. So that in performance is where SELECT will be a winner. … Read more
SET is the ANSI standard way of assigning values to variables, and SELECT is not. But you can use SELECT to assign values to more than one variable at a time. SET allows you to assign data to only one variable at a time. So that in performance is where SELECT will be a winner. … Read more
The API to control network emulation were added to ChromeDriver. And should be available for quite a while now. According to comment in the linked issue you should use version at least 2.26 because of some bugfix. According to Selenium changelog bindings are available for these languages: JavaScript as of version 3.4.0 (commit) Python as … Read more
I don’t really have experience with TVP yet, however there is an nice performance comparison chart vs. BULK INSERT in MSDN here. They say that BULK INSERT has higher startup cost, but is faster thereafter. In a remote client scenario they draw the line at around 1000 rows (for “simple” server logic). Judging from their … Read more
The heap profile shows active memory, memory the runtime believes is in use by the go program (ie: hasn’t been collected by the garbage collector). When the GC does collect memory the profile shrinks, but no memory is returned to the system. Your future allocations will try to use memory from the pool of previously … Read more
The reason is that the query optimizer does not do a very good job at costing user-defined functions. It decides, in some cases, that it would be cheaper to completely re-evaluate the function for each row, rather than incur the disk reads that might be necessary otherwise. SQL Server’s costing model does not inspect the … Read more
So as nobody has answered this I will put down what I did, it may not be the best way to do it so bear that in mind! I opened dev tools and setup a new profile under network speed where the latency was 1000ms and the speed to 50kb/s. (where it says “online” next … Read more
Generally yes, in-lane is still lower latency on SKX (1 cycle vs. 3), but usually it’s not worth spending extra instructions to use them instead of the powerful lane-crossing shuffles. However, vpermt2w and a couple other shuffles need multiple shuffle-port uops, so they cost as much as multiple simpler shuffles. Shuffle throughput very easily becomes … Read more