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Support CREATE, DROP statements in ApplySchema and online DDL #7083

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merged 9 commits into from Dec 9, 2020
Merged

Support CREATE, DROP statements in ApplySchema and online DDL #7083

merged 9 commits into from Dec 9, 2020

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shlomi-noach
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@shlomi-noach shlomi-noach commented Nov 29, 2020 •
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With this PR, we support CREATE TABLE and DROP TABLE statements to run as Online DDL. Right now this new functionality is only supported by vtctl ApplySchema, and not yet by vtgate queries.

e.g. you may vtctl ApplySchema -ddl_strategy "gh-ost" -sql "create table t(id int primary key); drop table t2" commerce

CREATE and DROP statements submitted this way are not executed immediately. Instead, they are scheduled, and pushed to the tablets through the Online DDL mechanism; tablets will run those queries with their own schedule/queue flow.

Reasons for this PR:

  • Generalizing the online DDL statements to more than just ALTER
  • Be able to group together multiple schema changes under same context (see also OnlineDDL: request_context/migration_context #7082), and have them executed more-or-less together, regardless of DDL type
  • In next steps: implicitly converting DROP TABLE statements to RENAME, as per Tracking issue: safe, lazy, managed DROP TABLE #6689, making DROP TABLE truly online DDL.
    • Note: this is still TBD, and we should break multi-table DROP statements into distinct single-table statements.

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Support CREATE, DROP statements in ApplySchema and online DDL
d839167 
Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
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shlomi-noach commented Nov 29, 2020 •
edited

  • TODO: endtoend tests

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fixed unit test
90452df 
Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
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added CREATE/DROP online DDL endtoend tests
496f28c 
Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
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I'm considering how to set a more general ddl_strategy, since "gh-ost" and "pt-osc" obviously do not apply to CREATE and DROP statements.

Current line of thought:

  • if -ddl_strategy is set to pt-osc or gh-ost, then this is online DDL, and CREATE and DROP and statements should go online.
  • introduce -ddl_strategy "online". It's a more general purpose setting. For CREATE and DROP statements it makes sense.
    For ALTER statements it's a bit more vague and I'm thinking whenever we have online strategy then vitess should dynamically pick gh-ost or pt-osc. I'll keep thinking about this.

@shlomi-noach
trigger early next invocation of onMigrationCheckTick upon:
2f06eb6 
- migration completion
- migration failure
- new INSERT to schema_migrations
throttle invocation of onMigrationCheckTick() to at most 1/sec

Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
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triggering initial tick early on
a1ac2cf 
Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
@shlomi-noach
TODO comment
e167fa9 
Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
@shlomi-noach shlomi-noach marked this pull request as ready for review November 29, 2020 19:31
@shlomi-noach shlomi-noach requested a review from a team November 29, 2020 19:31
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Ready for review

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General context: #6926

This was referenced Dec 2, 2020
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merge upstream/master
d4fb510 
Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
@shlomi-noach shlomi-noach mentioned this pull request Dec 3, 2020
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Documentation PR: vitessio/website#623

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Merge branch 'master' into online-ddl-create-drop-online
93bc2ed
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goimports
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Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
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🙏 @vitessio/ps-vitess request for review

rohit-nayak-ps
rohit-nayak-ps approved these changes Dec 9, 2020
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lgtm

@shlomi-noach shlomi-noach merged commit 7703097 into vitessio:master Dec 9, 2020
@shlomi-noach shlomi-noach deleted the online-ddl-create-drop-online branch December 9, 2020 15:50
@askdba askdba added this to the v9.0 milestone Dec 10, 2020
@shlomi-noach shlomi-noach mentioned this pull request Dec 23, 2020
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@rafael rafael mentioned this pull request Mar 17, 2021
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@rohit-nayak-ps rohit-nayak-ps rohit-nayak-ps approved these changes

@sougou sougou Awaiting requested review from sougou

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