Alex Behm has posted comments on this change.

Change subject: IMPALA-5347: Parquet scanner microoptimizations
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Patch Set 2:

(7 comments)

http://gerrit.cloudera.org:8080/#/c/6950/2/be/src/exec/hdfs-parquet-scanner.cc
File be/src/exec/hdfs-parquet-scanner.cc:

Line 937:     if (template_tuple_ == nullptr && tuple_byte_size_ <= 
CACHE_LINE_SIZE) {
Might be worth putting this into an InitBatch() function.


http://gerrit.cloudera.org:8080/#/c/6950/2/be/src/exec/parquet-column-readers.cc
File be/src/exec/parquet-column-readers.cc:

Line 486:     uint8_t val_buf[sizeof(T)]; // Uninitialized stack allocation for 
temporary value.
Comment just seems to describe what this line is doing, but not why. Mention 
explicitly what we are trying to avoid for a perf gain.


http://gerrit.cloudera.org:8080/#/c/6950/2/be/src/util/bit-stream-utils.inline.h
File be/src/util/bit-stream-utils.inline.h:

Line 91: ALWAYS_INLINE inline bool BitReader::GetValue(int num_bits, T* v) {
remove inline?


http://gerrit.cloudera.org:8080/#/c/6950/2/be/src/util/dict-encoding.h
File be/src/util/dict-encoding.h:

Line 291: ALWAYS_INLINE inline bool DictDecoder<T>::GetNextValue(T* value) {
remove inline?


Line 304: ALWAYS_INLINE inline bool DictDecoder<Decimal16Value>::GetNextValue(
remove inline?


http://gerrit.cloudera.org:8080/#/c/6950/2/be/src/util/rle-encoding.h
File be/src/util/rle-encoding.h:

Line 251: ALWAYS_INLINE inline bool RleDecoder::Get(T* val) {
remove inline?


Line 269:     if (UNLIKELY(!bit_reader_.GetValue(bit_width_, val))) return 
false;
Really a critical change? It changes the behavior, so might be dangerous / 
introduce a bug.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I49ec523a65542fdbabd53fbcc4a8901d769e5cd5
Gerrit-PatchSet: 2
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Tim Armstrong <[email protected]>
Gerrit-Reviewer: Alex Behm <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-Reviewer: anujphadke <[email protected]>
Gerrit-HasComments: Yes

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