Tim Armstrong has posted comments on this change.

Change subject: IMPALA-3286: Prefetching for PHJ probing.
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Patch Set 3:

(3 comments)

The abstraction seems better and the join code is easier to follow. I think Dan 
covered most of it, but i had a couple of questions

http://gerrit.cloudera.org:8080/#/c/2959/3/be/src/exec/hash-table.h
File be/src/exec/hash-table.h:

Line 321: expr_values_null_byte_array_
> expr_values_null_bool_array_
I've seen some comments elsewhere that say something about uint8_t better than 
bool for codegen. I'm unsure if that's true.


http://gerrit.cloudera.org:8080/#/c/2959/3/be/src/exec/partitioned-hash-join-node-ir.cc
File be/src/exec/partitioned-hash-join-node-ir.cc:

Line 265: vals_buf->IsRowNull(idx))
Would it make sense to make this part of the iterator? Either by storing the 
index in the iterator, or making it a byte array so that you can use a pointer 
like the other values.


http://gerrit.cloudera.org:8080/#/c/2959/3/be/src/runtime/row-batch.h
File be/src/runtime/row-batch.h:

Line 151:         int limit = FIXED_LEN_BUFFER_LIMIT) :
What's this about? Is this just some experimenting?


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Gerrit-MessageType: comment
Gerrit-Change-Id: Ib42b93d99d09c833571e39d20d58c11ef73f3cc0
Gerrit-PatchSet: 3
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Michael Ho <[email protected]>
Gerrit-Reviewer: Dan Hecht <[email protected]>
Gerrit-Reviewer: Michael Ho <[email protected]>
Gerrit-Reviewer: Mostafa Mokhtar <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-HasComments: Yes

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