Online DDL: ready_to_complete hint column #9813
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Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
shlomi-noach
added
Component: Query Serving
release notes none
Type: Enhancement
dbussink
approved these changes
Mar 2, 2022
| "-online_ddl_check_interval", "3s", | ||
| "-schema_change_check_interval", "1", |
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Doesn't matter, but any reason this order of arguments was changed?
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Bedtime story: it turns out the onlineddl_ghost endtoend tests have not been running in a while. There was an exception thrown in this old TestMain function that was not caught (in itself something to investigate). What I did now was to copy+paste a brand new TestMain function from onlineddl_vrepl tests, which works.
Having said that, I'll reorder the arguments just to keep this PR cleaner.
go/vt/vttablet/onlineddl/executor.go
Outdated
| if ddlAction == sqlparser.AlterStr || !postponeCompletion { | ||
| // Any non-postponed migration can be scheduled | ||
| // postponed ALTER can be scheduled | ||
| // We only schedule a single migration i nthe execution of this function |
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Typo here, i nthe instead of in the.
Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
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Description
This PR adds
ready_to_completecolumn in_vt.schema_migrationswhich is then visible inSHOW VITESS_MIGRATIONS ...output.The use case is intended for postponed migrations (although it provides visibility for non-postponed migrations as well): if a migration is postponed, the user wants to know "is now a good time to cut-over" ie run a
ALTER VITESS_MIGRATION ... COMPLETEand expect a near-immediate cut-over.ready_to_completeis a boolean (values0or1) that indicates that the migration is generally capable of cutting over. Specifically:CREATEandDROPmigrations will always exhibit the value of1(immediately or shortly after submission). Note that this is true even if the migrations are stillqueued. Once they exhibit1, they stay with1.vitessALTERmigrations will indicate1when row-copy is complete and vplayer's lag is generally good. this value can drop back to0when the migration is postponed and vplayer happens to accumulate lag. Once vplayer is caught up again, it will flip back to1.REVERTof any of the above behaves similarly: aCREATEREVERTimmediately exhibits the value of1; anALTER'sREVERTexhibits1when vplayer's lag is good and0when vplayer accumulates laggh-ostALTERmigrations indicate1when entering postponed state, and does not have lag indication. It is only applicable topostponed-completionmigrations.Note that all changes to
onSchemaMigrationStatusare for supportinggh-ostby adding a hint column togh-ostcallback API; it's not the important part of this PR.Related Issue(s)
Tracking: #6926
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