Jim Apple has posted comments on this change. Change subject: IMPALA-5347: Parquet scanner microoptimizations ......................................................................
Patch Set 5: (2 comments) http://gerrit.cloudera.org:8080/#/c/6950/5/be/src/exec/parquet-column-readers.cc File be/src/exec/parquet-column-readers.cc: Line 315: /// Use __restrict__ so that the compiler knows that it is safe to cache member Just so I'm clear: __restrict__ on the method implies that 'this' isn't aliased by any other pointers. However, 'num_values' already was assumed by the compiler not to alias 'this' because 'int' and 'decltype(*this)' do not match. On the other hand, uint8_t is the same as unsigned char on our platform, so 'tuple_mem' could alias 'this', so it also needs a __restrict__? If that's right, I think the comment could expand a bit more to clarify this to future readers. Line 489: uint8_t val_buf[sizeof(T)]; Also needs aligning as T, right? -- To view, visit http://gerrit.cloudera.org:8080/6950 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-MessageType: comment Gerrit-Change-Id: I49ec523a65542fdbabd53fbcc4a8901d769e5cd5 Gerrit-PatchSet: 5 Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-Owner: Tim Armstrong <[email protected]> Gerrit-Reviewer: Alex Behm <[email protected]> Gerrit-Reviewer: Jim Apple <[email protected]> Gerrit-Reviewer: Mostafa Mokhtar <[email protected]> Gerrit-Reviewer: Tim Armstrong <[email protected]> Gerrit-Reviewer: anujphadke <[email protected]> Gerrit-HasComments: Yes
