[
https://issues.apache.org/jira/browse/IMPALA-4356?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16840835#comment-16840835
]
ASF subversion and git services commented on IMPALA-4356:
---------------------------------------------------------
Commit d4648e87b4bc0c05203f6af0f4448dc2017bda80 in impala's branch
refs/heads/master from Tim Armstrong
[ https://gitbox.apache.org/repos/asf?p=impala.git;h=d4648e8 ]
IMPALA-4356,IMPALA-7331: codegen all ScalarExprs
Based on initial draft patch by Pooja Nilangekar.
Codegen'd expressions can be executed in two ways - either by
being called directly from a fully codegend function, or from
interpreted code via a function pointer (previously
ScalarFnCall::scalar_fn_wrapper_).
This change moves the function pointer from ScalarFnCall to its
base class ScalarExpr, so the full expr tree can be codegen'd, not
just the ScalarFnCall subtrees. The key refactoring and improvements
are:
* ScalarExpr::Get*Val() switches between interpreted and the codegen'd
function pointer code paths in an inline function, avoiding a
virtual function call to ScalarFnCal::Get*Val().
* Boilerplate logic is moved to ScalarExpr::GetCodegendComputeFn(),
which calls a virtual function GetCodegenComputeFnImpl().
* ScalarFnCall's logic for deciding whether to interpret or codegen is
better abstracted and exposed to ScalarExpr as IsInterpretable()
and ShouldCodegen() methods.
* The ScalarExpr::codegend_compute_fn_ function pointer is only
populated for expressions that are "codegen entry points". These
include the roots of expr trees and non-root expressions
where the parent expression calls Get*Val() from the
pseudo-codegend GetCodegendComputeFnWrapper().
* ScalarFnCall is always initialised for interpreted execution.
Otherwise the function pointer is needed for non-root expressions,
e.g. to support ScalarExprEvaluator::GetConstantVal().
* Latent bugs/gaps for codegen of CollectionVal are fixed. CollectionVal
is modified to use the StringVal memory layout to allow code sharing
with StringVal. These fixes allowed simplification of
IsNotEmptyPredicate codegen (from IMPALA-7657).
I chose to tackle two problems in one change - adding support for
generating codegen'd function pointers for all ScalarExprs, and adding
the "entry point" concept - to avoid a blow-up in the number of
codegen'd entry points that could lead to longer codegen times and/or
worse code because of inlining changes.
IMPALA-7331 (CHAR codegen support functions) is also fixed because
it was simpler to enable CHAR codegen within ScalarExpr than to carry
forward the exiting CHAR workarounds from ScalarFnCall. The
CHAR-specific codegen support required in the scalar expr subsystem is
very limited. StringVal intermediates are used everywhere. Only
SlotRef actually operates on the different tuple layout, and the
required codegen support for SlotRef already exists for UDA
intermediates anyway.
Testing:
* Ran exhaustive tests.
Perf:
* Ran a basic insert benchmark, which went from 10.1s to 7.6s
create table foo stored as parquet as
select case when l_orderkey % 2 = 0 then 'aaa' else 'bbb' end
from tpch30_parquet.lineitem;
* Ran a basic CHAR expr test:
set num_nodes=1;
set mt_dop=1;
select count(*) from lineitem
where cast(l_linestatus as CHAR(2)) = 'O ' and
cast(l_returnflag as CHAR(2)) = 'N '
The time spent in the scan went from 520ms to 220ms.
* Added perf regression test to tpcds-insert, similar to the manual
benchmark.
* Ran single-node TPC-H with large and small scale factors, to estimate
impact on execution perf and query startup time, respectively.
+----------+-----------------------+---------+------------+------------+----------------+
| Workload | File Format | Avg (s) | Delta(Avg) | GeoMean(s) |
Delta(GeoMean) |
+----------+-----------------------+---------+------------+------------+----------------+
| TPCH(30) | parquet / none / none | 6.84 | -0.18% | 4.49 | -0.31%
|
+----------+-----------------------+---------+------------+------------+----------------+
+----------+----------+-----------------------+--------+-------------+------------+-----------+----------------+-------+----------------+---------+--------+
| Workload | Query | File Format | Avg(s) | Base Avg(s) |
Delta(Avg) | StdDev(%) | Base StdDev(%) | Iters | Median Diff(%) | MW Zval |
Tval |
+----------+----------+-----------------------+--------+-------------+------------+-----------+----------------+-------+----------------+---------+--------+
| TPCH(30) | TPCH-Q20 | parquet / none / none | 2.58 | 2.47 | +4.18%
| 1.29% | 0.88% | 5 | +4.12% | 2.31 | 5.81 |
| TPCH(30) | TPCH-Q17 | parquet / none / none | 4.81 | 4.61 | +4.33%
| 2.18% | 2.15% | 5 | +3.91% | 1.73 | 3.09 |
| TPCH(30) | TPCH-Q21 | parquet / none / none | 26.45 | 26.16 | +1.09%
| 0.37% | 0.50% | 5 | +1.36% | 2.02 | 3.94 |
| TPCH(30) | TPCH-Q9 | parquet / none / none | 15.92 | 15.75 | +1.09%
| 2.87% | 1.65% | 5 | +0.88% | 0.29 | 0.73 |
| TPCH(30) | TPCH-Q12 | parquet / none / none | 2.38 | 2.35 | +1.12%
| 1.64% | 1.11% | 5 | +0.80% | 1.15 | 1.26 |
| TPCH(30) | TPCH-Q14 | parquet / none / none | 2.94 | 2.91 | +1.13%
| 7.68% | 5.37% | 5 | -0.34% | -0.29 | 0.27 |
| TPCH(30) | TPCH-Q18 | parquet / none / none | 18.10 | 18.02 | +0.42%
| 2.70% | 0.56% | 5 | +0.28% | 0.29 | 0.34 |
| TPCH(30) | TPCH-Q8 | parquet / none / none | 4.72 | 4.72 | -0.04%
| 1.20% | 1.65% | 5 | +0.05% | 0.00 | -0.04 |
| TPCH(30) | TPCH-Q19 | parquet / none / none | 3.92 | 3.93 | -0.26%
| 1.08% | 2.36% | 5 | +0.20% | 0.58 | -0.23 |
| TPCH(30) | TPCH-Q6 | parquet / none / none | 1.27 | 1.27 | -0.28%
| 0.22% | 0.88% | 5 | +0.09% | 0.29 | -0.68 |
| TPCH(30) | TPCH-Q16 | parquet / none / none | 2.64 | 2.65 | -0.45%
| 1.65% | 0.65% | 5 | -0.24% | -0.58 | -0.57 |
| TPCH(30) | TPCH-Q22 | parquet / none / none | 3.10 | 3.13 | -0.76%
| 1.47% | 1.12% | 5 | -0.21% | -0.29 | -0.93 |
| TPCH(30) | TPCH-Q2 | parquet / none / none | 1.20 | 1.21 | -0.80%
| 2.26% | 2.47% | 5 | -0.82% | -1.15 | -0.53 |
| TPCH(30) | TPCH-Q4 | parquet / none / none | 1.97 | 1.99 | -1.37%
| 1.84% | 3.21% | 5 | -0.47% | -0.58 | -0.83 |
| TPCH(30) | TPCH-Q13 | parquet / none / none | 11.53 | 11.63 | -0.91%
| 0.46% | 0.49% | 5 | -0.95% | -2.02 | -3.08 |
| TPCH(30) | TPCH-Q10 | parquet / none / none | 5.13 | 5.21 | -1.51%
| 2.24% | 4.05% | 5 | -0.94% | -0.58 | -0.73 |
| TPCH(30) | TPCH-Q5 | parquet / none / none | 3.61 | 3.66 | -1.40%
| 0.66% | 0.79% | 5 | -1.33% | -1.73 | -3.05 |
| TPCH(30) | TPCH-Q7 | parquet / none / none | 19.42 | 19.71 | -1.52%
| 1.34% | 1.39% | 5 | -1.22% | -1.44 | -1.76 |
| TPCH(30) | TPCH-Q3 | parquet / none / none | 5.08 | 5.15 | -1.49%
| 1.34% | 0.73% | 5 | -1.35% | -1.44 | -2.20 |
| TPCH(30) | TPCH-Q15 | parquet / none / none | 3.42 | 3.49 | -1.92%
| 0.93% | 1.47% | 5 | -1.53% | -1.15 | -2.49 |
| TPCH(30) | TPCH-Q11 | parquet / none / none | 1.15 | 1.19 | -3.17%
| 2.27% | 1.95% | 5 | -4.21% | -1.15 | -2.41 |
| TPCH(30) | TPCH-Q1 | parquet / none / none | 9.26 | 9.63 | -3.85%
| 0.62% | 0.59% | 5 | -3.78% | -2.31 | -10.25 |
+----------+----------+-----------------------+--------+-------------+------------+-----------+----------------+-------+----------------+---------+--------+
Cluster Name: UNKNOWN
Lab Run Info: UNKNOWN
Impala Version: impalad version 3.2.0-SNAPSHOT RELEASE ()
Baseline Impala Version: impalad version 3.2.0-SNAPSHOT RELEASE (2019-03-19)
+----------+-----------------------+---------+------------+------------+----------------+
| Workload | File Format | Avg (s) | Delta(Avg) | GeoMean(s) |
Delta(GeoMean) |
+----------+-----------------------+---------+------------+------------+----------------+
| TPCH(2) | parquet / none / none | 0.90 | -0.08% | 0.80 | -0.05%
|
+----------+-----------------------+---------+------------+------------+----------------+
+----------+----------+-----------------------+--------+-------------+------------+-----------+----------------+-------+----------------+---------+-------+
| Workload | Query | File Format | Avg(s) | Base Avg(s) |
Delta(Avg) | StdDev(%) | Base StdDev(%) | Iters | Median Diff(%) | MW Zval |
Tval |
+----------+----------+-----------------------+--------+-------------+------------+-----------+----------------+-------+----------------+---------+-------+
| TPCH(2) | TPCH-Q18 | parquet / none / none | 1.22 | 1.19 | +1.93%
| 3.81% | 4.46% | 20 | +3.34% | 1.62 | 1.46 |
| TPCH(2) | TPCH-Q10 | parquet / none / none | 0.74 | 0.73 | +1.97%
| 3.36% | 2.94% | 20 | +0.97% | 1.88 | 1.95 |
| TPCH(2) | TPCH-Q11 | parquet / none / none | 0.49 | 0.48 | +1.91%
| 6.19% | 4.64% | 20 | +0.25% | 0.95 | 1.09 |
| TPCH(2) | TPCH-Q4 | parquet / none / none | 0.43 | 0.43 | +1.99%
| 6.26% | 5.86% | 20 | +0.15% | 0.92 | 1.03 |
| TPCH(2) | TPCH-Q15 | parquet / none / none | 0.50 | 0.49 | +1.82%
| 7.32% | 6.35% | 20 | +0.26% | 1.01 | 0.83 |
| TPCH(2) | TPCH-Q1 | parquet / none / none | 0.98 | 0.97 | +0.79%
| 4.64% | 2.73% | 20 | +0.36% | 0.77 | 0.65 |
| TPCH(2) | TPCH-Q19 | parquet / none / none | 0.83 | 0.83 | +0.65%
| 3.33% | 2.80% | 20 | +0.44% | 2.18 | 0.67 |
| TPCH(2) | TPCH-Q14 | parquet / none / none | 0.62 | 0.62 | +0.97%
| 2.86% | 1.00% | 20 | +0.04% | 0.13 | 1.42 |
| TPCH(2) | TPCH-Q3 | parquet / none / none | 0.88 | 0.87 | +0.57%
| 2.17% | 1.74% | 20 | +0.29% | 1.15 | 0.92 |
| TPCH(2) | TPCH-Q12 | parquet / none / none | 0.53 | 0.53 | +0.27%
| 4.58% | 5.78% | 20 | +0.46% | 1.47 | 0.16 |
| TPCH(2) | TPCH-Q17 | parquet / none / none | 0.72 | 0.72 | +0.15%
| 3.64% | 5.55% | 20 | +0.21% | 0.86 | 0.10 |
| TPCH(2) | TPCH-Q21 | parquet / none / none | 2.05 | 2.05 | +0.21%
| 1.99% | 2.37% | 20 | +0.01% | 0.25 | 0.30 |
| TPCH(2) | TPCH-Q5 | parquet / none / none | 1.28 | 1.27 | +0.24%
| 1.61% | 1.80% | 20 | -0.02% | -0.57 | 0.44 |
| TPCH(2) | TPCH-Q13 | parquet / none / none | 1.27 | 1.27 | -0.34%
| 1.69% | 1.83% | 20 | -0.20% | -1.65 | -0.61 |
| TPCH(2) | TPCH-Q7 | parquet / none / none | 1.72 | 1.73 | -0.55%
| 2.40% | 1.69% | 20 | -0.03% | -0.42 | -0.83 |
| TPCH(2) | TPCH-Q8 | parquet / none / none | 1.27 | 1.28 | -0.68%
| 3.10% | 3.89% | 20 | -0.06% | -0.54 | -0.62 |
| TPCH(2) | TPCH-Q6 | parquet / none / none | 0.36 | 0.36 | -0.84%
| 0.79% | 3.51% | 20 | -0.07% | -0.36 | -1.04 |
| TPCH(2) | TPCH-Q2 | parquet / none / none | 0.65 | 0.65 | -1.17%
| 4.76% | 5.99% | 20 | -0.05% | -0.25 | -0.69 |
| TPCH(2) | TPCH-Q9 | parquet / none / none | 1.59 | 1.62 | -2.01%
| 1.45% | 5.12% | 20 | -0.16% | -1.24 | -1.69 |
| TPCH(2) | TPCH-Q20 | parquet / none / none | 0.68 | 0.69 | -1.73%
| 4.35% | 4.43% | 20 | -0.49% | -1.74 | -1.25 |
| TPCH(2) | TPCH-Q22 | parquet / none / none | 0.38 | 0.40 | -2.89%
| 7.42% | 6.39% | 20 | -0.21% | -0.66 | -1.34 |
| TPCH(2) | TPCH-Q16 | parquet / none / none | 0.59 | 0.62 | -4.01%
| 6.33% | 5.83% | 20 | -4.72% | -1.39 | -2.13 |
+----------+----------+-----------------------+--------+-------------+------------+-----------+----------------+-------+----------------+---------+-------+
Change-Id: I839d7a3a2f5e1309c33a1f66013ef11628c5dc11
Reviewed-on: http://gerrit.cloudera.org:8080/12797
Reviewed-by: Impala Public Jenkins <[email protected]>
Tested-by: Impala Public Jenkins <[email protected]>
> Automatically codegen expressions with any root Expr node
> ---------------------------------------------------------
>
> Key: IMPALA-4356
> URL: https://issues.apache.org/jira/browse/IMPALA-4356
> Project: IMPALA
> Issue Type: Improvement
> Components: Backend
> Affects Versions: Impala 2.8.0
> Reporter: Tim Armstrong
> Assignee: Tim Armstrong
> Priority: Major
> Labels: codegen
> Fix For: Impala 3.3.0
>
>
> Currently Impala only automatically codegens expression subtrees with
> ScalarFnCall at the root. This is the expression type used to implement many
> but not all expressions (including most builtin operators). One example of an
> expression that is not automatically codegened is "case" statements.
> The crux of this is to move ScalarFnCall::scalar_fn_wrapper_ into ScalarExpr
> (and probably rename it). There are some consequential changes required to
> make this work. Instead of each ScalarExpr subclass overriding Get*Val(), I
> think Get*Val() should be a non-virtual method of ScalarExpr that either
> calls the codegen'd function or calls into Get*ValInterpreted(), which would
> be the new virtual function.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
