Make DROP/CREATE DATABASE pluggable by systay · Pull Request #7381 · vitessio/vitess

systay · 2021-01-26T06:55:57Z

Allows CREATE and DROP database to have behaviour controlled by a plugin.

Fixes #7525

Signed-off-by: Andres Taylor <andres@planetscale.com>

GuptaManan100

👍

go/vt/vtgate/engine/create_database.go

go/vt/vtgate/planbuilder/create_database_pluggable.go

go/vt/vtgate/engine/create_database.go

Signed-off-by: Andres Taylor <andres@planetscale.com>

go/vt/vtgate/engine/create_database.go

Signed-off-by: Andres Taylor <andres@planetscale.com>

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

Signed-off-by: Andres Taylor <andres@planetscale.com>

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

enisoc

This looks great! I just had one question about adding a wait step for DROP DATABASE as well.

enisoc · 2021-03-05T19:48:11Z

go/vt/vtgate/engine/dbddl.go

+		return &sqltypes.Result{RowsAffected: 1}, nil
+	}
+
+	err := plugin.DropDatabase(ctx, c.name)


We had discussed that after the plugin says it's done, we should wait until vtgate observes that the keyspace is gone. The idea is to mimic the semantic in MySQL, which is that it's safe to re-create a database immediately after DROP DATABASE returns. So we should probably check whatever signal we check when handling CREATE DATABASE here and wait for that signal to say the keyspace doesn't exist. WDYT?

We had discussed that after the plugin says it's done, we should wait until vtgate observes that the keyspace is gone. The idea is to mimic the semantic in MySQL, which is that it's safe to re-create a database immediately after DROP DATABASE returns. So we should probably check whatever signal we check when handling CREATE DATABASE here and wait for that signal to say the keyspace doesn't exist. WDYT?

Just want to call it out that the current implementation depends on the plugin to take care of changing topo server metadata to tell us that keyspace is created or deleted.
I have added the necessary checks to ensure that.

Also you can change the query timeout with query like create database /*vt+ QUERY_TIMEOUT_MS=30000 */ <database_name>

Just want to call it out that the current implementation depends on the plugin to take care of changing topo server metadata to tell us that keyspace is created or deleted.

That works for me. I just wanted vtgate to take care of the question, "Can this vtgate instance see the keyspace yet/still?" since the plugin can't determine that from topo alone.

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

enisoc · 2021-03-09T17:07:18Z

go/vt/vtgate/engine/dbddl.go

+		return &sqltypes.Result{RowsAffected: 1}, nil
+	}
+
+	err := plugin.DropDatabase(ctx, c.name)


Just want to call it out that the current implementation depends on the plugin to take care of changing topo server metadata to tell us that keyspace is created or deleted.

That works for me. I just wanted vtgate to take care of the question, "Can this vtgate instance see the keyspace yet/still?" since the plugin can't determine that from topo alone.

enisoc · 2021-03-09T17:19:11Z

go/vt/vtgate/engine/dbddl.go

+	if err != nil {
+		return nil, err
+	}
+	for vcursor.FindKeyspace(c.name) {


It looks like vcursor.FindKeyspace() does a direct topo call, which checks the source of truth, but it doesn't check whether this particular vtgate instance has observed the change yet.

My goal was to guarantee that an immediate CREATE DATABASE x after DROP DATABASE x on the same vtgate session will succeed. It looks like CREATE DATABASE checks vschema.KeyspaceExists(ksName) to determine whether the keyspace exists. Wouldn't we want to check the same thing to guarantee that vtgate will allow it?

I changed it to use vschema.

enisoc · 2021-03-09T17:22:14Z

go/vt/vtgate/vcursor_impl.go

+
+func (vc *vcursorImpl) FindKeyspace(ks string) bool {
+	_, err := vc.topoServer.GetKeyspace(vc.ctx, ks)
+	return err == nil


Won't this mean that a transient error communicating with topo will make us assume the keyspace doesn't exist? It seems like anything that makes a remote call should return error as well to be honest about the possibility that it might fail to get an answer at all. We would only translate the NotFound/NoNode error to false, nil.

now this is not an issue.

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

enisoc · 2021-03-09T20:29:21Z

go/vt/vtgate/vcursor_impl.go

+}
+
+func (vc *vcursorImpl) FindKeyspace(ks string) bool {
+	return vc.KeyspaceExists(ks)


It looks like KeyspaceExists() reads from the vschema.Keyspaces map without a mutex, which implies that the map is never updated by another goroutine. Doesn't that mean the result of this call will never change, even if vtgate has refreshed vschema in the background?

I changed that to see the executor view of VSchema.
The e2e test confirms that you can do create/drop multiple times in order.

RebuildVSchemaGraph is necessary to update the executor's view.

… available Signed-off-by: Harshit Gangal <harshit@planetscale.com>

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

Signed-off-by: Andres Taylor <andres@planetscale.com>

…ger available to be served Signed-off-by: Harshit Gangal <harshit@planetscale.com>

enisoc

LGTM. Thanks for doing the heavy lifting on waiting for vtgate to observe changes. This should make my job writing the plugin very easy! :)

Start of making CREATE DATABASE pluggable

b7400d4

Signed-off-by: Andres Taylor <andres@planetscale.com>

systay force-pushed the create-database branch from 46c2f01 to b7400d4 Compare January 26, 2021 06:57

systay added 2 commits January 26, 2021 08:14

use more restrictive type

f85d458

Signed-off-by: Andres Taylor <andres@planetscale.com>

use simpler API for the CREATE DB API

768719e

Signed-off-by: Andres Taylor <andres@planetscale.com>

systay closed this Feb 2, 2021

systay reopened this Feb 22, 2021

systay added 2 commits February 22, 2021 06:54

Merge remote-tracking branch 'upstream/master' into create-database

9d200e1

Signed-off-by: Andres Taylor <andres@planetscale.com>

make it possible to do both create and drop using a plugin

668b66f

Signed-off-by: Andres Taylor <andres@planetscale.com>

systay changed the title ~~Start of making CREATE DATABASE pluggable~~ Make DROP/CREATE DATABASE pluggable Feb 22, 2021

GuptaManan100 approved these changes Feb 23, 2021

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systay commented Feb 23, 2021

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go/vt/vtgate/engine/create_database.go Outdated Show resolved Hide resolved

enisoc reviewed Feb 25, 2021

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go/vt/vtgate/planbuilder/create_database_pluggable.go Outdated Show resolved Hide resolved

go/vt/vtgate/engine/create_database.go Outdated Show resolved Hide resolved

go/vt/vtgate/engine/create_database.go Outdated Show resolved Hide resolved

systay added 2 commits March 2, 2021 16:44

adressed PR review

80b184f

Signed-off-by: Andres Taylor <andres@planetscale.com>

Merge remote-tracking branch 'upstream/master' into create-database

b324b06

Signed-off-by: Andres Taylor <andres@planetscale.com>

systay force-pushed the create-database branch from d36e8fc to b324b06 Compare March 2, 2021 16:01

enisoc reviewed Mar 2, 2021

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go/vt/vtgate/engine/create_database.go Outdated Show resolved Hide resolved

systay and others added 12 commits March 3, 2021 08:43

[wip] refactored lots of things

7e776c8

Signed-off-by: Andres Taylor <andres@planetscale.com>

code refactor

cd26ee2

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

e2e test fir dbddl plugin

02e49ce

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

[wip] implement the dbddl primitive

a429c60

Signed-off-by: Andres Taylor <andres@planetscale.com>

implemented more of the primitive

90b697d

Signed-off-by: Andres Taylor <andres@planetscale.com>

Merge remote-tracking branch 'upstream/master' into create-database

a32812c

Signed-off-by: Andres Taylor <andres@planetscale.com>

fix the primitive on create db and implement drop db

6657063

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

e2e test for drop db

c77f7c5

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

fix dbdddl plugin unit test

73eb606

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

dbddl: code refactor

c8569f0

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

added comments to dbddl

295f848

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

added comments directive to set query timeout in db ddl primitive

10daa0e

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

harshit-gangal requested a review from enisoc March 4, 2021 15:48

added timeout test

131c5f9

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

harshit-gangal marked this pull request as ready for review March 5, 2021 11:53

harshit-gangal self-requested a review as a code owner March 5, 2021 11:53

enisoc reviewed Mar 5, 2021

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harshit-gangal added 2 commits March 9, 2021 00:02

drop database to wait for vschema to be updated

9a33429

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

fix plan test

afd6e57

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

enisoc reviewed Mar 9, 2021

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on drop database call, check if keyspace is removed from vschema

6a92f2d

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

deepthi mentioned this pull request Mar 9, 2021

Create db #7246

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7 tasks

enisoc reviewed Mar 9, 2021

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harshit-gangal and others added 4 commits March 11, 2021 01:07

check resolve destination for drop database to see if keyspace is not…

06da2d7

… available Signed-off-by: Harshit Gangal <harshit@planetscale.com>

Merge branch 'master' of github.com:vitessio/vitess into create-database

00bf410

Signed-off-by: Harshit Gangal <harshit@planetscale.com>

make sure to not return error when things worked

e762d58

Signed-off-by: Andres Taylor <andres@planetscale.com>

watch vschema in drop database to confirm that the keyspace is no lon…

6a7f295

…ger available to be served Signed-off-by: Harshit Gangal <harshit@planetscale.com>

harshit-gangal requested a review from enisoc March 11, 2021 12:59

harshit-gangal mentioned this pull request Mar 11, 2021

create and drop database plugin documentation vitessio/website#723

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enisoc approved these changes Mar 11, 2021

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harshit-gangal merged commit 8f7a239 into vitessio:master Mar 11, 2021

harshit-gangal deleted the create-database branch March 11, 2021 16:33

askdba added the Component: Query Serving label Mar 18, 2021

askdba added this to the v10.0 milestone Mar 18, 2021

deepthi mentioned this pull request Mar 31, 2021

vttestserver: "Test" plugins for CREATE/DROP database #7770

Closed

deepthi mentioned this pull request Apr 19, 2021

docker-compose: "Test" plugins for CREATE/DROP database #7893

Open

ajm188 mentioned this pull request Jul 15, 2021

slack vitess v10.pre tinyspeck/vitess#228

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systay commented Jan 26, 2021 •

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