simplified hash calculation for varchars in constant time#608
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markonussbaum wants to merge 1 commit intomainfrom
Draft
simplified hash calculation for varchars in constant time#608markonussbaum wants to merge 1 commit intomainfrom
markonussbaum wants to merge 1 commit intomainfrom
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A very simple, but fast hash implementation for nullable_varchar.
Instead of iterating over all characters in O(n), it just samples the first, last and median element of the varchar in O(1), resulting in a speedup in many cases.
Result with TPC-H at scale 10 on vh001:
Old implementation:
real 64m30.605s
user 0m15.766s
sys 0m2.302s
With this PR:
real 49m39.123s
user 0m14.275s
sys 0m2.093s
The test was done with