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From "Tim Armstrong (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-5560: always store CHAR(N) inline in tuple
Date Fri, 30 Jun 2017 18:17:30 GMT
Hello Dan Hecht,

I'd like you to reexamine a change.  Please visit

    http://gerrit.cloudera.org:8080/7303

to look at the new patch set (#6).

Change subject: IMPALA-5560: always store CHAR(N) inline in tuple
......................................................................

IMPALA-5560: always store CHAR(N) inline in tuple

This is done to simplify the CHAR(N) logic. I believe this is overall an
improvement - any benefits of the out-of-line storage that motivated
this optimisation originally were outweighed by the added complexity.

This also avoids IMPALA-5559 (fe/be have different notions of var-len),
which will unblock IMPALA-3200.

Pros:
* Reduce the number of code paths and improve test coverage.
  (e.g. avoids IMPALA-5559: fe/be have different notions of var-len)
* Reduced memory to store non-NULL data (saves 12-byte StringValue)
* Fewer branches in code -> save CPU cycles.
* If CHAR(N) performance is important, reduced complexity makes it
  easier to implement codegen.

Cons:
* Requires N bytes to store a NULL value.
* May hurt cache locality (although this is speculative in my mind).

The change is mostly mechanical - I removed MAX_CHAR_INLINE_LENGTH
and then removed branches that depended on that.

Testing:
Ran exhaustive build.

Change-Id: I9c0b823ccff6b0c37f5267c548d096c29b8caac3
---
M be/src/exec/hash-table.cc
M be/src/exec/hdfs-avro-scanner-test.cc
M be/src/exec/hdfs-parquet-table-writer.cc
M be/src/exec/hdfs-text-table-writer.cc
M be/src/exec/parquet-column-readers.cc
M be/src/exprs/agg-fn-evaluator.cc
M be/src/exprs/anyval-util.h
M be/src/exprs/scalar-expr-evaluator.cc
M be/src/exprs/slot-ref.cc
M be/src/runtime/raw-value-ir.cc
M be/src/runtime/raw-value.cc
M be/src/runtime/raw-value.inline.h
M be/src/runtime/string-value.h
M be/src/runtime/string-value.inline.h
M be/src/runtime/types.h
M be/src/service/fe-support.cc
M be/src/service/hs2-util.cc
M fe/src/main/java/org/apache/impala/catalog/ScalarType.java
M testdata/workloads/functional-query/queries/QueryTest/spilling.test
19 files changed, 69 insertions(+), 130 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/03/7303/6
-- 
To view, visit http://gerrit.cloudera.org:8080/7303
To unsubscribe, visit http://gerrit.cloudera.org:8080/settings

Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I9c0b823ccff6b0c37f5267c548d096c29b8caac3
Gerrit-PatchSet: 6
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-Reviewer: Dan Hecht <dhecht@cloudera.com>
Gerrit-Reviewer: Matthew Jacobs <mj@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>

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