[ https://issues.apache.org/jira/browse/HIVE-18866?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16412467#comment-16412467 ]
Gopal V commented on HIVE-18866:
--------------------------------
This codepath also runs hot during the HLL computation for column stats on Double & Longs.
{code}
15.83 │ movzbq 0x18(%r10,%rsi,1),%rax
0.03 │ cmp %ebx,%ecx
│ . jae 32d
0.03 │ vmovd %ebx,%xmm0
0.00 │ vmovd %edx,%xmm1
0.02 │ movslq %r13d,%r14
2.81 │ movzbq 0x19(%r10,%r14,1),%r8
2.79 │ movzbq 0x1f(%r10,%r14,1),%rcx
0.45 │ movzbq 0x1a(%r10,%r14,1),%rbx
0.60 │ movzbq 0x1b(%r10,%r14,1),%rdx
0.41 │ movzbq 0x1c(%r10,%r14,1),%rsi
1.63 │ movzbq 0x1d(%r10,%r14,1),%r13
0.78 │ movzbq 0x1e(%r10,%r14,1),%r14
{code}
> Semijoin: Implement a Long -> Hash64 vector fast-path
> -----------------------------------------------------
>
> Key: HIVE-18866
> URL: https://issues.apache.org/jira/browse/HIVE-18866
> Project: Hive
> Issue Type: Improvement
> Components: Vectorization
> Reporter: Gopal V
> Priority: Major
> Labels: performance
> Attachments: perf-hash64-long.png
>
>
> A significant amount of CPU is wasted with JMM restrictions on byte[] arrays.
> To transform from one Long -> another Long, this goes into a byte[] array, which shows up as a hotspot.
> !perf-hash64-long.png!
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