Marcel Kornacker has posted comments on this change.

Change subject: IMPALA-2736: Basic column-wise slot materialization in Parquet 
scanner.
......................................................................


Patch Set 8:

(10 comments)

http://gerrit.cloudera.org:8080/#/c/2779/8/be/src/exec/hdfs-parquet-scanner.cc
File be/src/exec/hdfs-parquet-scanner.cc:

Line 329:       uint8_t* tuple_mem, int* num_values) {
describe role of tuple_mem


Line 369:   bool ReadValueBatch(MemPool* pool, int max_values, int tuple_size,
instead of having this be templated, why not inline the code at the call sites 
and remove the template param. there are only 8 lines of shared code, which 
isn't worth the extra indirection and complication through the template 
parameter.

also, the function call overhead should be negligible in this case, so you can 
move this to the .cc file.


Line 708:   virtual bool ReadValue(MemPool* pool, Tuple* tuple) {
do we still need this?


Line 723:     return ReadValueBatch<false>(pool, max_values, tuple_size, 
tuple_mem, num_values);
same comment about inlining the call of the templated function applies here


Line 755:   template<bool IN_COLLECTION>
since we're now dealing with batches, it would be nice to get rid of the 
template parameters.


Line 1722:   // This function most not be called when the output batch is 
already full. As long as
must


Line 1797:     ++stats->total_possible;
todo: do these stats updates outside the loop if possible, as in 
stats->total_possible += num_scratch_tuples


Line 1801:     // producing an output batch.
good idea


Line 1874:         continue_execution = col_reader->ReadNonRepeatedValueBatch(
is there a more graceful name? ReadScalarValueBatch? TopLevelValueBatch?


http://gerrit.cloudera.org:8080/#/c/2779/8/be/src/exec/hdfs-parquet-scanner.h
File be/src/exec/hdfs-parquet-scanner.h:

Line 484:   template <bool IN_COLLECTION>
the comment says top-level tuples, how can in_collection be true? (or: what 
does in_collection mean?)


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Gerrit-MessageType: comment
Gerrit-Change-Id: I72a613fa805c542e39df20588fb25c57b5f139aa
Gerrit-PatchSet: 8
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Alex Behm <[email protected]>
Gerrit-Reviewer: Alex Behm <[email protected]>
Gerrit-Reviewer: Marcel Kornacker <[email protected]>
Gerrit-Reviewer: Mostafa Mokhtar <[email protected]>
Gerrit-Reviewer: Skye Wanderman-Milne <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-HasComments: Yes

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