[IMPALA-7367] Pack StringValue, CollectionValue and TimestampValue slots

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: Impala 3.2.0
• Component/s: Backend
• Labels: performance
• Target Version: Product Backlog
• Epic Color: ghx-label-5
• Assignee: Pooja Nilangekar
• Reporter: Tim Armstrong
• Created: 30/Jul/18 17:06
• Updated: 07/Feb/23 11:14
• Resolved: 19/Nov/18 17:52

Description

This is a follow-on to finish up the work from IMPALA-2789. IMPALA-2789 didn't actually fully pack the memory layout because StringValue, TimestampValue and CollectionValue still occupy 16 bytes but only have 12 bytes of actual data. This results in a higher memory footprint, which leads to higher memory requirements and worse performance. We don't get any benefit from the padding since the majority of tuples are not actually aligned in memory anyway.

I did a quick version of the change for StringValue only which improves TPC-H performance.

Report Generated on 2018-07-30
Run Description: "b5608264b4552e44eb73ded1e232a8775c3dba6b vs f1e401505ac20c0400eec819b9196f7f506fb927"

Cluster Name: UNKNOWN
Lab Run Info: UNKNOWN
Impala Version:          impalad version 3.1.0-SNAPSHOT RELEASE ()
Baseline Impala Version: impalad version 3.1.0-SNAPSHOT RELEASE (2018-07-27)

+----------+-----------------------+---------+------------+------------+----------------+
| Workload | File Format           | Avg (s) | Delta(Avg) | GeoMean(s) | Delta(GeoMean) |
+----------+-----------------------+---------+------------+------------+----------------+
| TPCH(10) | parquet / none / none | 2.69    | -4.78%     | 2.09       | -3.11%         |
+----------+-----------------------+---------+------------+------------+----------------+

+----------+----------+-----------------------+--------+-------------+------------+------------+----------------+-------------+-------+
| Workload | Query    | File Format           | Avg(s) | Base Avg(s) | Delta(Avg) | StdDev(%)  | Base StdDev(%) | Num Clients | Iters |
+----------+----------+-----------------------+--------+-------------+------------+------------+----------------+-------------+-------+
| TPCH(10) | TPCH-Q22 | parquet / none / none | 0.94   | 0.93        |   +0.75%   |   3.37%    |   2.84%        | 1           | 30    |
| TPCH(10) | TPCH-Q13 | parquet / none / none | 3.32   | 3.32        |   +0.13%   |   1.74%    |   2.09%        | 1           | 30    |
| TPCH(10) | TPCH-Q11 | parquet / none / none | 0.99   | 0.99        |   -0.02%   |   3.74%    |   3.16%        | 1           | 30    |
| TPCH(10) | TPCH-Q5  | parquet / none / none | 2.30   | 2.33        |   -0.96%   |   2.15%    |   2.45%        | 1           | 30    |
| TPCH(10) | TPCH-Q2  | parquet / none / none | 1.55   | 1.57        |   -1.45%   |   1.65%    |   1.49%        | 1           | 30    |
| TPCH(10) | TPCH-Q8  | parquet / none / none | 2.89   | 2.93        |   -1.51%   |   2.69%    |   1.34%        | 1           | 30    |
| TPCH(10) | TPCH-Q9  | parquet / none / none | 5.96   | 6.06        |   -1.63%   |   1.34%    |   1.82%        | 1           | 30    |
| TPCH(10) | TPCH-Q20 | parquet / none / none | 1.58   | 1.61        |   -1.85%   |   2.28%    |   2.16%        | 1           | 30    |
| TPCH(10) | TPCH-Q16 | parquet / none / none | 1.18   | 1.21        |   -2.11%   |   3.68%    |   4.72%        | 1           | 30    |
| TPCH(10) | TPCH-Q3  | parquet / none / none | 2.13   | 2.18        |   -2.31%   |   2.09%    |   1.92%        | 1           | 30    |
| TPCH(10) | TPCH-Q15 | parquet / none / none | 1.86   | 1.90        |   -2.52%   |   2.06%    |   2.22%        | 1           | 30    |
| TPCH(10) | TPCH-Q17 | parquet / none / none | 1.85   | 1.90        |   -2.86%   |   10.00%   |   8.02%        | 1           | 30    |
| TPCH(10) | TPCH-Q10 | parquet / none / none | 2.58   | 2.66        |   -2.93%   |   1.68%    |   6.49%        | 1           | 30    |
| TPCH(10) | TPCH-Q14 | parquet / none / none | 1.37   | 1.42        |   -3.22%   |   3.35%    |   6.24%        | 1           | 30    |
| TPCH(10) | TPCH-Q18 | parquet / none / none | 4.99   | 5.17        |   -3.38%   |   1.75%    |   3.82%        | 1           | 30    |
| TPCH(10) | TPCH-Q6  | parquet / none / none | 0.66   | 0.69        |   -3.73%   |   5.04%    |   4.12%        | 1           | 30    |
| TPCH(10) | TPCH-Q4  | parquet / none / none | 1.07   | 1.12        |   -3.97%   |   1.79%    |   2.85%        | 1           | 30    |
| TPCH(10) | TPCH-Q1  | parquet / none / none | 2.29   | 2.39        |   -4.34%   |   2.70%    |   3.43%        | 1           | 30    |
| TPCH(10) | TPCH-Q7  | parquet / none / none | 6.17   | 6.45        |   -4.42%   |   2.15%    |   1.69%        | 1           | 30    |
| TPCH(10) | TPCH-Q19 | parquet / none / none | 1.85   | 1.93        |   -4.42%   |   2.76%    |   2.26%        | 1           | 30    |
| TPCH(10) | TPCH-Q12 | parquet / none / none | 1.32   | 1.42        |   -6.75%   |   2.55%    |   3.56%        | 1           | 30    |
| TPCH(10) | TPCH-Q21 | parquet / none / none | 10.43  | 12.08       |   -13.69%  | * 14.21% * | * 10.76% *     | 1           | 30    |
+----------+----------+-----------------------+--------+-------------+------------+------------+----------------+-------------+-------+

Issue Links

• breaks: IMPALA-8151 HiveUdfCall assumes StringValue is 16 bytes
• is depended upon by: IMPALA-5490 Upgrade to GCC 7.x or greater
• is related to: IMPALA-340 Improve internal format of strings
• relates to: KUDU-1694 C++ client support for specifying tuple memory layout