*: not send tso request when point get with max tso (#11981) #16336
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Signed-off-by: sre-bot <[email protected]>
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LGTM |
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tiancaiamao
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Apr 14, 2020
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cherry-pick #11981 to release-3.1
What problem does this PR solve?
Point get without double read will use maxUint64 as transaction tso. Then no need to send tso request to PD.
This PR will delay to get txn future after try fast point, so it may have a little performance regression in the case of need to get tso from PD. Especially in the situation of point get with double read.
BenchMark
Environment: In my local machine: 1 TiDB, 1 PD, 5 TiKV.
Best case: Point get with max tso
Before
This PR
Worst case: Point get with double read can't use max tso
Before
In this PR
As you can see, since I delay use get txn future, there is a performance regression is this situation.
What is changed and how it works?
Check List
Tests
Code changes