Sameer Abhyankar has posted comments on this change. Change subject: KUDU-1363: Add in-list predicates for extracting a set of equalities. ......................................................................
Patch Set 7: > > The main reason for not using unordered_set was because the > > collection would still be storing pointers instead of actual > values > > and I did not think I could get an O(1) lookup when i am > searching > > for a pointer-to-a-value in a set-of-pointers. PredicateData > doesnt > > know about the the type of the value and defers the comparison to > > TypeInfo. As a result, PredicateData only holds void* or a > > collection(vector) of void*. > > > > The other (not so critical) reason I went with a vector vs an > > unordered_set was because I do care about the order of the list > > (which is sorted/deduped) when I push Upper/Lower bound key > > predicates in key_util. I suppose, I could sort and pick the > > min/max values from the collection in key_util itself instead of > > using a vector. However, using a vector just made it convenient. > > Your second point is a valid one; std::unordered_set would be > inappropriate if you need to find lower/upper bounds often (I think > this happens in the predicate pushdown code that I didn't review). > But what about std::set? It's implemented by a red-black tree and > so it'd still be more efficient than std::vector. > > As to your first point, whichever container you use, you can pass a > custom hash and equal_to (for unordered_set) or comparator (for > set) that workers properly for KuduValue pointers. The > implementation would dereference the pointer, dereference the > private Data pointer inside it, and, using the definition of > KuduValue::Data in value-internal.h, operate on the actual data. OK..let me take a look at it today. -- To view, visit http://gerrit.cloudera.org:8080/2986 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-MessageType: comment Gerrit-Change-Id: I986cb13097f1cf4af2b752f58c4c38f412a6a598 Gerrit-PatchSet: 7 Gerrit-Project: kudu Gerrit-Branch: master Gerrit-Owner: Sameer Abhyankar <abhyan...@gmail.com> Gerrit-Reviewer: Adar Dembo <a...@cloudera.com> Gerrit-Reviewer: Dan Burkert <d...@cloudera.com> Gerrit-Reviewer: Kudu Jenkins Gerrit-Reviewer: Sameer Abhyankar <abhyan...@gmail.com> Gerrit-Reviewer: Todd Lipcon <t...@apache.org> Gerrit-HasComments: No
