VDiff: Add control for start/resume and stop

[mattlord]

Description

VDiffs can be pretty resource intensive and for larger clusters and tables, it can be very desirable to have greater control over how they are executed. This PR implements two feature requests that allow you to fully control when and where it's running — on a shard by shard basis.

Example usage in the PR branch:

cd examples/local
alias vtctldclient='command vtctldclient --server=localhost:15999'

./101_initial_cluster.sh; mysql < ../common/insert_commerce_data.sql; ./201_customer_tablets.sh; ./202_move_tables.sh; ./203_switch_reads.sh; ./204_switch_writes.sh; ./205_clean_commerce.sh; ./301_customer_sharded.sh; ./302_new_shards.sh; ./303_reshard.sh; ./304_switch_reads.sh; ./305_switch_writes.sh; ./306_down_shard_0.sh; ./307_delete_shard_0.sh

vtctldclient ApplyVSchema --vschema-file /tmp/customer.json customer

vtctldclient MoveTables --workflow commerce2customer --target-keyspace customer create --source-keyspace commerce --tables "product"

❯ vtctldclient --server localhost:15999 vdiff --workflow commerce2customer --target-keyspace customer create --auto-start=false
VDiff 280206aa-72ef-4073-aee8-76b219d55c08 scheduled on target shards, use show to view progress

❯ vtctldclient vdiff --workflow commerce2customer --target-keyspace customer show ca5cb9fe-900a-43ec-b5be-e80a67fa8ec3 --verbose --format json
{
  "Workflow": "commerce2customer",
  "Keyspace": "customer",
  "State": "stopped",
  "UUID": "ca5cb9fe-900a-43ec-b5be-e80a67fa8ec3",
  "RowsCompared": 0,
  "HasMismatch": false,
  "Shards": "-80,80-"
}

❯ vtctldclient vdiff --workflow commerce2customer --target-keyspace customer resume ca5cb9fe-900a-43ec-b5be-e80a67fa8ec3 --target-shards "80-"
VDiff resume scheduled

❯ vtctldclient vdiff --workflow commerce2customer --target-keyspace customer show ca5cb9fe-900a-43ec-b5be-e80a67fa8ec3 --verbose --format json
{
  "Workflow": "commerce2customer",
  "Keyspace": "customer",
  "State": "stopped",
  "UUID": "ca5cb9fe-900a-43ec-b5be-e80a67fa8ec3",
  "RowsCompared": 2,
  "HasMismatch": false,
  "Shards": "-80,80-",
  "StartedAt": "2024-08-29 18:28:37",
  "TableSummary": {
    "product": {
      "TableName": "product",
      "State": "completed",
      "RowsCompared": 2,
      "MatchingRows": 2,
      "MismatchedRows": 0,
      "ExtraRowsSource": 0,
      "ExtraRowsTarget": 0
    }
  },
  "Reports": {
    "product": {
      "80-": {
        "TableName": "product",
        "ProcessedRows": 2,
        "MatchingRows": 2,
        "MismatchedRows": 0,
        "ExtraRowsSource": 0,
        "ExtraRowsTarget": 0
      }
    }
  }
}

❯ vtctldclient vdiff --workflow commerce2customer --target-keyspace customer resume ca5cb9fe-900a-43ec-b5be-e80a67fa8ec3 --target-shards "-80"
VDiff resume scheduled

❯ vtctldclient vdiff --workflow commerce2customer --target-keyspace customer show ca5cb9fe-900a-43ec-b5be-e80a67fa8ec3 --verbose --format json
{
  "Workflow": "commerce2customer",
  "Keyspace": "customer",
  "State": "completed",
  "UUID": "ca5cb9fe-900a-43ec-b5be-e80a67fa8ec3",
  "RowsCompared": 2,
  "HasMismatch": false,
  "Shards": "-80,80-",
  "StartedAt": "2024-08-29 18:28:37",
  "CompletedAt": "2024-08-29 19:07:34",
  "TableSummary": {
    "product": {
      "TableName": "product",
      "State": "completed",
      "RowsCompared": 2,
      "MatchingRows": 2,
      "MismatchedRows": 0,
      "ExtraRowsSource": 0,
      "ExtraRowsTarget": 0
    }
  },
  "Reports": {
    "product": {
      "-80": {
        "TableName": "product",
        "ProcessedRows": 0,
        "MatchingRows": 0,
        "MismatchedRows": 0,
        "ExtraRowsSource": 0,
        "ExtraRowsTarget": 0
      },
      "80-": {
        "TableName": "product",
        "ProcessedRows": 2,
        "MatchingRows": 2,
        "MismatchedRows": 0,
        "ExtraRowsSource": 0,
        "ExtraRowsTarget": 0
      }
    }
  }
}

Related Issue(s)

• Fixes: Feature Request: VDiff support create without starting #13776
• Fixes: Feature Request: VDIff support stop and resume specific target shard #13777

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation: Update docs for 16654 and 16709 website#1835

[vitess-bot]

Review Checklist

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[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 66 lines in your changes missing coverage. Please review.

Project coverage is 68.94%. Comparing base (5ced946) to head (9eabc9d).
Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
go/vt/vttablet/tabletmanager/vdiff/action.go	0.00%	47 Missing ⚠️
...d/vtctldclient/command/vreplication/vdiff/vdiff.go	45.45%	6 Missing ⚠️
.../vtctldclient/command/vreplication/common/utils.go	0.00%	5 Missing ⚠️
go/vt/vtctl/grpcvtctldserver/server.go	0.00%	3 Missing ⚠️
go/vt/vtctl/workflow/utils.go	82.35%	3 Missing ⚠️
go/vt/vtctl/workflow/server.go	87.50%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16654      +/-   ##
==========================================
+ Coverage   68.92%   68.94%   +0.01%     
==========================================
  Files        1565     1565              
  Lines      201682   201745      +63     
==========================================
+ Hits       139010   139090      +80     
+ Misses      62672    62655      -17     

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[rohit-nayak-ps]

Other than preferring auto-start to do-not-start as the flag name, everything looks good!

[rohit-nayak-ps]

we should probably call it auto-start to be consistent with the workflow create commands.

[mattlord]

That's what I started with, but the problem then is that if you do not specify the field — which older clients would not do — then the default/zero value is false and it's not started.

[rohit-nayak-ps]

autoStart := subFlags.Bool("auto_start", true, "If false, streams will start in the Stopped state and will need to be explicitly started")

Shouldn't this definition, from vrep workflows, work? Default is true and user needs to specify --auto_start=false to start vdiff in a stopped state.

[mattlord]

This is an issue at the proto / RPC layer. Any client sending an older request object will not include that field. So it will be false (the zero value) on the server side

[mattlord]

I'll try making it optional so that it's a *bool. Then we start it unless a value of false was specifically provided (would be nil in older client requests).

[mattlord]

Made that change here: 0020b0f

I'm good either way, so let's go with that if you prefer it.

[maxenglander]

❤️