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VReplication: send unique key name to rowstreamer, which can then use with FORCE INDEX #14916

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merged 3 commits into from
Jan 10, 2024
Merged

VReplication: send unique key name to rowstreamer, which can then use with FORCE INDEX #14916

merged 3 commits into from
Jan 10, 2024

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shlomi-noach
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Description

Fixes #14915

This PR adds:

  • force_unique_key field in filter/rule.
  • OnlineDDL populates this field with desired unique key name.
  • Field sent to rowstreamer as query hint.
  • If rowstreamer sees said query hint, then it adds FORCE INDEX (...) to the streaming query.

Note: still unsure what's the best way to add testing. The observable changes are that the rowstreamer query now includes a force index clause, e.g.:

476:I0109 16:37:05.522045 4149073 rowstreamer.go:332] Streaming query: select /*+ MAX_EXECUTION_TIME(3600000) */ id, col1, alternative_id from t force index (`alternative_id_idx`) order by alternative_id

vstreamer/engine populates the query hint like so:

460:I0109 16:36:20.914991 4149073 engine.go:280] Streaming rows for query select /*vt+ ukColumns="alternative_id" ukForce="alternative_id_idx" */ id, col1, alternative_id from t, lastpk: []

Related Issue(s)

#14915

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 was added or is not required

Deployment Notes

@shlomi-noach
filter/rule: add force_unique_key field. OnlineDDL populates force_un…
4e0be63 
…ique_key, rowstreamer reads it and uses the value as FORCE INDEX hint

Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
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vitess-bot bot commented Jan 9, 2024

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@vitess-bot vitess-bot bot added NeedsBackportReason If backport labels have been applied to a PR, a justification is required NeedsDescriptionUpdate The description is not clear or comprehensive enough, and needs work NeedsIssue A linked issue is missing for this Pull Request NeedsWebsiteDocsUpdate What it says labels Jan 9, 2024
@github-actions github-actions bot added this to the v19.0.0 milestone Jan 9, 2024
@shlomi-noach
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I'm suggesting this should be backported to supported versions. Opinions?

@shlomi-noach shlomi-noach removed NeedsDescriptionUpdate The description is not clear or comprehensive enough, and needs work NeedsWebsiteDocsUpdate What it says NeedsIssue A linked issue is missing for this Pull Request labels Jan 9, 2024
@rohit-nayak-ps
Add unit test for the force index hints
a7d82b4 
Signed-off-by: Rohit Nayak <rohit@planetscale.com>
mattlord
mattlord approved these changes Jan 10, 2024
View reviewed changes
go/vt/vttablet/onlineddl/vrepl.go
@@ -619,6 +620,7 @@ func (v *VRepl) analyzeBinlogSource(ctx context.Context) {
SourceUniqueKeyColumns: encodeColumns(&v.chosenSourceUniqueKey.Columns),
TargetUniqueKeyColumns: encodeColumns(&v.chosenTargetUniqueKey.Columns),
SourceUniqueKeyTargetColumns: encodeColumns(v.chosenSourceUniqueKey.Columns.MappedNamesColumnList(v.sharedColumnsMap)),
ForceUniqueKey: url.QueryEscape(v.chosenSourceUniqueKey.Name),
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I'm curious why we're doing URL escaping?

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It's for when the index name has spaces, or quotes, or other special characters. The query hints parser will otherwise be unable to parse it correctly. Consider select /*vt+ ukForce="an index with spaces" */ -- the parser will only parse "an".

go/vt/vttablet/tabletserver/vstreamer/rowstreamer_test.go Outdated
Comment on lines 54 to 56
if directives == "" {
return fmt.Sprintf(queryTemplate, "")
}
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These lines are unnecessary as the subsequent line would return the same thing when directives is an empty string.

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Removed redundant code.

go/vt/vttablet/tabletserver/vstreamer/rowstreamer_test.go
Comment on lines +61 to +64
{"", "force index (`PRIMARY`) order by id"},
{"/*vt+ ukColumns=\"uk1\" ukForce=\"uk2\" */", "force index (`uk2`) order by uk1"},
{"/*vt+ ukForce=\"uk2\" */", "force index (`uk2`) order by uk1"},
{"/*vt+ ukColumns=\"uk1\" */", "order by uk1"},
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I feel like we could probably use a few more test cases, but this might be enough.

@shlomi-noach
remove redundant code
2e73b8b 
Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
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codecov bot commented Jan 10, 2024

Codecov Report

All modified and coverable lines are covered by tests ✅

❗ No coverage uploaded for pull request base (main@6a0cc44). Click here to learn what that means.

Additional details and impacted files 
@@           Coverage Diff           @@
##             main   #14916   +/-   ##
=======================================
  Coverage        ?   47.28%           
=======================================
  Files           ?     1136           
  Lines           ?   238493           
  Branches        ?        0           
=======================================
  Hits            ?   112761           
  Misses          ?   117121           
  Partials        ?     8611

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@shlomi-noach
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IMO this should be backported to supported versions seeing that vstreamer could run into degraded/impossible performance situations. The fix itself is fairly safe.

@shlomi-noach shlomi-noach added Backport to: release-16.0 and removed NeedsBackportReason If backport labels have been applied to a PR, a justification is required labels Jan 10, 2024
@shlomi-noach shlomi-noach merged commit 61b12e6 into vitessio:main Jan 10, 2024
106 of 107 checks passed
@shlomi-noach shlomi-noach deleted the rowstreamer-force-uk branch January 10, 2024 09:56
This was referenced Jan 10, 2024
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@shlomi-noach
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All backports have conflicts, that is expected.

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Reviewers

@rohit-nayak-ps rohit-nayak-ps rohit-nayak-ps approved these changes

@mattlord mattlord mattlord approved these changes

@deepthi deepthi Awaiting requested review from deepthi deepthi is a code owner

@harshit-gangal harshit-gangal Awaiting requested review from harshit-gangal harshit-gangal is a code owner

@systay systay Awaiting requested review from systay systay is a code owner

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Successfully merging this pull request may close these issues.

Bug Report: MySQL can choose filesort plan for rowstreamer non-PK reads, leading to repeated stream timeouts
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@shlomi-noach @mattlord @rohit-nayak-ps