impala-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Michael Ho (Code Review)" <>
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:

File be/src/exec/

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

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

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

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.
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().

Line 226: resourcs
> resources.

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.
File be/src/exec/

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

Line 477: cur_row
> The logic around cur_row is a little hard to follow, since it is the loop v
File be/src/exec/

Line 678: probe_exp_ctxs_
> Typoe: 'expr_ctxs_'

Line 1005:  
> Extra space

To view, visit
To unsubscribe, visit

Gerrit-MessageType: comment
Gerrit-Change-Id: Ib42b93d99d09c833571e39d20d58c11ef73f3cc0
Gerrit-PatchSet: 11
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Michael Ho <>
Gerrit-Reviewer: Dan Hecht <>
Gerrit-Reviewer: Huaisi Xu <>
Gerrit-Reviewer: Michael Ho <>
Gerrit-Reviewer: Mostafa Mokhtar <>
Gerrit-Reviewer: Tim Armstrong <>
Gerrit-HasComments: Yes

View raw message