6 ms·
Using a sequence instead of a map is fine if you know it will never be more than some small number of entries, but so often we are wrong about how many entries
by oconnor0 9y ago
Using a sequence instead of a map is fine if you know it will never be more than some small number of entries, but so often we are wrong about how many entries will be in a table that the N-squared use of a sequence as a map kills performance unexpectedly.
- adrianN 9y agoBut that's what profiling is for.
- arjie 9y agoThat argument favours hashmaps by default, though. After all, they're all right at small sizes and much better at big sizes.
- usefulcat 9y agoProfiling won't tell you what the chances are that the collection will someday need to contain more than N elements.
- adrianN 9y agoYou don't replace every map in your code with a distributed Key-Value store, in case it might need to store terabytes in the future. Most of the time you have a pretty good idea whether a map has to store a hundred, or a hundred thousand elements.