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From "Michael Ho (Code Review)" <ger...@cloudera.org>
Subject [Impala-CR](cdh5-trunk) IMPALA-3286: Prefetching for PHJ probing.
Date Mon, 16 May 2016 20:49:10 GMT
Michael Ho has posted comments on this change.

Change subject: IMPALA-3286: Prefetching for PHJ probing.
......................................................................


Patch Set 11:

(15 comments)

http://gerrit.cloudera.org:8080/#/c/2959/11/be/src/exec/hash-table-test.cc
File be/src/exec/hash-table-test.cc:

Line 185:     runtime_state_->InitMemTrackers(TUniqueId(), NULL, -1);
> Let's just do this in CreateQueryState().
Done


Line 241:  runtime_state_->query_mem_tracker()
> It would be better to use the test mem_tracker_ we set up.
Done


http://gerrit.cloudera.org:8080/#/c/2959/11/be/src/exec/hash-table.cc
File be/src/exec/hash-table.cc:

Line 125:   // TODO: use tr1::array?
> We can delete this TODO, I don't think it's very helpful, especially since 
Done


Line 131: inline
> This probably doesn't need to be inline, does it?
Yes, kept it when moving it from the header file to here. Probably not worth it.


http://gerrit.cloudera.org:8080/#/c/2959/11/be/src/exec/hash-table.h
File be/src/exec/hash-table.h:

Line 126:   /// Allocate various buffers for storing expression evaluation results, hash values,
> We should have a HashTableCtx::Create() function that allocates and initial
Good idea. Done.


Line 128:   Status Init(RuntimeState* state, int num_build_tuples, MemTracker* tracker);
> Also mention what 'tracker' is (it seems at least as important to document 
Added comments in the constructor.


Line 130:   /// Call to cleanup any resources.
> Mention that 'tracker' is the same 'tracker' passed to Init().
Done


Line 226: resourcs
> resources.
Done


Line 346:     Bitmap null_bitmap_;
> I feel like it would be simpler to just do an array of uint8_t to be consis
IMHO, higher memory density means lower cache footprint and helps reduce the pressure of L1
cache so I think there is some benefit for using bitmap here as a larger boolean array may
end up evicting  other hot data from the relatively small L1 cache.

I actually think we should convert the expr_values_null_array_ to bitmap too given its potential
size but I will not do so in this change as it bitmap interface may need to be changed slightly.


http://gerrit.cloudera.org:8080/#/c/2959/11/be/src/exec/partitioned-hash-join-node-ir.cc
File be/src/exec/partitioned-hash-join-node-ir.cc:

Line 336: batch_size
> cache_size
Renamed to prefetch_size to be consistent with InsertBatch() below.


Line 378: has_probe_rows 
This fixes IMPALA-3510.


Line 476: row_idices
> typo: row_indices
Done


Line 477: cur_row
> The logic around cur_row is a little hard to follow, since it is the loop v
Done


http://gerrit.cloudera.org:8080/#/c/2959/11/be/src/exec/partitioned-hash-join-node.cc
File be/src/exec/partitioned-hash-join-node.cc:

Line 678: probe_exp_ctxs_
> Typoe: 'expr_ctxs_'
Done


Line 1005:  
> Extra space
Done


-- 
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Gerrit-MessageType: comment
Gerrit-Change-Id: Ib42b93d99d09c833571e39d20d58c11ef73f3cc0
Gerrit-PatchSet: 11
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Michael Ho <kwho@cloudera.com>
Gerrit-Reviewer: Dan Hecht <dhecht@cloudera.com>
Gerrit-Reviewer: Huaisi Xu <hxu@cloudera.com>
Gerrit-Reviewer: Michael Ho <kwho@cloudera.com>
Gerrit-Reviewer: Mostafa Mokhtar <mmokhtar@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-HasComments: Yes

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