storage: optimize MVCCExportToSST range key processing

[erikgrinaker]

This patch optimizes MVCCExportToSST by making use of
RangeKeyChanged(), CloneInto(), and PutRawMVCCRangeKey().
Unfortunately, this did not appear to have a significant impact on
performance in the 0/1 range key cases, as most of the gains were
already realized by previously migrating MVCCIncrementalIterator to
RangeKeyChanged().

name                                                                                      old time/op  new time/op   delta
MVCCExportToSST/numKeys=64/numRevisions=1/exportAllRevisions=false/numRangeKeys=0-24      69.8µs ± 0%   69.9µs ± 1%    ~     (p=0.841 n=5+5)
MVCCExportToSST/numKeys=64/numRevisions=1/exportAllRevisions=false/numRangeKeys=1-24       116µs ± 7%    113µs ± 6%    ~     (p=0.548 n=5+5)
MVCCExportToSST/numKeys=64/numRevisions=1/exportAllRevisions=true/numRangeKeys=0-24       66.9µs ± 1%   66.6µs ± 1%    ~     (p=0.151 n=5+5)
MVCCExportToSST/numKeys=64/numRevisions=1/exportAllRevisions=true/numRangeKeys=1-24       98.4µs ± 7%  105.6µs ± 4%    ~     (p=0.095 n=5+5)
MVCCExportToSST/numKeys=64/numRevisions=10/exportAllRevisions=false/numRangeKeys=0-24      171µs ± 4%    166µs ± 4%    ~     (p=0.222 n=5+5)
MVCCExportToSST/numKeys=64/numRevisions=10/exportAllRevisions=false/numRangeKeys=1-24      229µs ± 4%    230µs ± 3%    ~     (p=0.841 n=5+5)
MVCCExportToSST/numKeys=64/numRevisions=10/exportAllRevisions=true/numRangeKeys=0-24       277µs ± 3%    270µs ± 2%    ~     (p=0.151 n=5+5)
MVCCExportToSST/numKeys=64/numRevisions=10/exportAllRevisions=true/numRangeKeys=1-24       345µs ± 2%    346µs ± 1%    ~     (p=1.000 n=5+5)
MVCCExportToSST/numKeys=1024/numRevisions=1/exportAllRevisions=false/numRangeKeys=0-24     617µs ± 1%    614µs ± 1%    ~     (p=0.310 n=5+5)
MVCCExportToSST/numKeys=1024/numRevisions=1/exportAllRevisions=false/numRangeKeys=1-24     762µs ± 1%    756µs ± 1%    ~     (p=0.151 n=5+5)
MVCCExportToSST/numKeys=1024/numRevisions=1/exportAllRevisions=true/numRangeKeys=0-24      571µs ± 2%    556µs ± 1%  -2.60%  (p=0.032 n=5+5)
MVCCExportToSST/numKeys=1024/numRevisions=1/exportAllRevisions=true/numRangeKeys=1-24      705µs ± 1%    700µs ± 1%    ~     (p=0.222 n=5+5)
MVCCExportToSST/numKeys=1024/numRevisions=10/exportAllRevisions=false/numRangeKeys=0-24   2.17ms ± 0%   2.19ms ± 1%  +0.80%  (p=0.008 n=5+5)
MVCCExportToSST/numKeys=1024/numRevisions=10/exportAllRevisions=false/numRangeKeys=1-24   2.87ms ± 1%   2.91ms ± 1%  +1.53%  (p=0.032 n=5+5)
MVCCExportToSST/numKeys=1024/numRevisions=10/exportAllRevisions=true/numRangeKeys=0-24    3.80ms ± 0%   3.79ms ± 1%    ~     (p=0.548 n=5+5)
MVCCExportToSST/numKeys=1024/numRevisions=10/exportAllRevisions=true/numRangeKeys=1-24    4.77ms ± 0%   4.75ms ± 0%    ~     (p=0.095 n=5+5)
MVCCExportToSST/numKeys=8192/numRevisions=1/exportAllRevisions=false/numRangeKeys=0-24    4.63ms ± 1%   4.57ms ± 1%  -1.24%  (p=0.008 n=5+5)
MVCCExportToSST/numKeys=8192/numRevisions=1/exportAllRevisions=false/numRangeKeys=1-24    5.61ms ± 0%   5.65ms ± 1%  +0.66%  (p=0.032 n=5+5)
MVCCExportToSST/numKeys=8192/numRevisions=1/exportAllRevisions=true/numRangeKeys=0-24     4.21ms ± 1%   4.14ms ± 0%  -1.69%  (p=0.008 n=5+5)
MVCCExportToSST/numKeys=8192/numRevisions=1/exportAllRevisions=true/numRangeKeys=1-24     5.23ms ± 0%   5.17ms ± 1%  -1.16%  (p=0.008 n=5+5)
MVCCExportToSST/numKeys=8192/numRevisions=10/exportAllRevisions=false/numRangeKeys=0-24   17.6ms ± 1%   17.8ms ± 2%    ~     (p=0.222 n=5+5)
MVCCExportToSST/numKeys=8192/numRevisions=10/exportAllRevisions=false/numRangeKeys=1-24   23.3ms ± 0%   23.6ms ± 0%  +1.10%  (p=0.008 n=5+5)
MVCCExportToSST/numKeys=8192/numRevisions=10/exportAllRevisions=true/numRangeKeys=0-24    30.9ms ± 0%   30.7ms ± 0%  -0.51%  (p=0.008 n=5+5)
MVCCExportToSST/numKeys=8192/numRevisions=10/exportAllRevisions=true/numRangeKeys=1-24    38.5ms ± 0%   38.4ms ± 0%    ~     (p=0.310 n=5+5)
MVCCExportToSST/numKeys=65536/numRevisions=1/exportAllRevisions=false/numRangeKeys=0-24   36.6ms ± 0%   36.1ms ± 1%  -1.46%  (p=0.008 n=5+5)
MVCCExportToSST/numKeys=65536/numRevisions=1/exportAllRevisions=false/numRangeKeys=1-24   44.5ms ± 0%   44.6ms ± 0%    ~     (p=0.310 n=5+5)
MVCCExportToSST/numKeys=65536/numRevisions=1/exportAllRevisions=true/numRangeKeys=0-24    33.4ms ± 1%   32.8ms ± 0%  -1.70%  (p=0.008 n=5+5)
MVCCExportToSST/numKeys=65536/numRevisions=1/exportAllRevisions=true/numRangeKeys=1-24    41.1ms ± 1%   40.7ms ± 0%  -1.04%  (p=0.008 n=5+5)
MVCCExportToSST/numKeys=65536/numRevisions=10/exportAllRevisions=false/numRangeKeys=0-24   152ms ± 1%    152ms ± 4%    ~     (p=1.000 n=5+5)
MVCCExportToSST/numKeys=65536/numRevisions=10/exportAllRevisions=false/numRangeKeys=1-24   197ms ± 0%    200ms ± 0%  +1.61%  (p=0.008 n=5+5)
MVCCExportToSST/numKeys=65536/numRevisions=10/exportAllRevisions=true/numRangeKeys=0-24    255ms ± 1%    253ms ± 0%  -0.56%  (p=0.032 n=5+5)
MVCCExportToSST/numKeys=65536/numRevisions=10/exportAllRevisions=true/numRangeKeys=1-24    314ms ± 0%    314ms ± 0%    ~     (p=0.730 n=4+5)

Release justification: bug fixes and low-risk updates to new functionality

Release note: None

[cockroach-teamcity]

This change is 

[erikgrinaker]

I ran a few CPU profiles here to find out why a single range key adds ~25% overhead. It seemed to all be down in Pebble, specifically interleavingIter.

For 23.1, we could reconsider whether we need interleaved exports, and instead export point/range keys separately (which would eliminate any penalty). However, we'll likely have to improve the interleavingIter performance for e.g. the scan case anyway, so it may be moot.

[erikgrinaker]

bors r=tbg

[craig]

Build failed (retrying...):

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[craig]

Build failed (retrying...):

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[craig]

Build succeeded:

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