[Impala-CR](cdh5-trunk) IMPALA-3780: avoid many small reads past end of block

["Dan Hecht (Code Review)" <ge...@cloudera.org>]

Dan Hecht has posted comments on this change.

Change subject: IMPALA-3780: avoid many small reads past end of block
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Patch Set 3: Code-Review+2

(4 comments)

http://gerrit.cloudera.org:8080/#/c/3518/3/be/src/exec/scanner-context.cc
File be/src/exec/scanner-context.cc:

Line 162:     read_past_buffer_size = ::min(read_past_buffer_size, max_buffer_size);
this is fine, but why is this min() needed now whereas it wasn't before?


Line 262:       RETURN_IF_ERROR(boundary_buffer_->EnsureCapacity(requested_len));
were there cases where requested_len is much larger than the number of bytes that can be read, and so pre-allocating it will waste a lot of memory?


http://gerrit.cloudera.org:8080/#/c/3518/3/be/src/exec/scanner-context.h
File be/src/exec/scanner-context.h:

PS3, Line 103: .
... (see GetNextBuffer()).


http://gerrit.cloudera.org:8080/#/c/3518/3/be/src/runtime/string-buffer.h
File be/src/runtime/string-buffer.h:

PS3, Line 99: int
this may conflict with Michael's 64-bit change (changed len's to 64-bits).


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Gerrit-MessageType: comment
Gerrit-Change-Id: Id90c5dea44f07dba5dd465cf325fbff28be34137
Gerrit-PatchSet: 3
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Tim Armstrong <ta...@cloudera.com>
Gerrit-Reviewer: Dan Hecht <dh...@cloudera.com>
Gerrit-Reviewer: Michael Ho
Gerrit-Reviewer: Tim Armstrong <ta...@cloudera.com>
Gerrit-HasComments: Yes