ddl: determine whether to use merge sort by each index separately #52000
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Codecov Report
Additional details and impacted files@@ Coverage Diff @@
## master #52000 +/- ##
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- Coverage 72.3939% 54.6311% -17.7628%
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Files 1481 1592 +111
Lines 365286 608874 +243588
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+ Hits 264445 332635 +68190
- Misses 81270 253092 +171822
- Partials 19571 23147 +3576
Flags with carried forward coverage won't be shown. Click here to find out more.
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| @@ -1175,7 +1175,7 @@ func (do *Domain) Init( | |||
| sysFac := func() (pools.Resource, error) { | |||
| return sysExecutorFactory(do) | |||
| } | |||
| sysCtxPool := pools.NewResourcePool(sysFac, 128, 128, resourceIdleTimeout) | |||
| sysCtxPool := pools.NewResourcePool(sysFac, 512, 512, resourceIdleTimeout) | |||
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What 128 to 512 mean?
| for i, g := range kvMetaGroups { | ||
| dataFiles := make([]string, 0, 1000) |
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Why not generate subtasks for each index that really needs merge sort？
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If we do this, in step 3, we need to scan subtasks meta from both step 2 and step 1.
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/retest |
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/ok-to-test |
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[APPROVALNOTIFIER] This PR is APPROVED This pull-request has been approved by: Benjamin2037, wjhuang2016 The full list of commands accepted by this bot can be found here. The pull request process is described here
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In response to a cherrypick label: new pull request created to branch |
What problem does this PR solve?
Issue Number: close #52004
Problem Summary:
Before this PR, when TiDB adds multiple indexes with global sort, merge sort step is determined by external file count of ALL indexes. For example, the threshold is 4000, there are 3 indexes with 3000 files respectively, then there are 9000(>4000) files. Merge sort step will be executed. However, merge sort is not necessary in this case, because the records from different indexes are not overlap.
What changed and how does it work?
Check List
Tests
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