OnlineDDL: reject duplicate UUID with different migration_context

[shlomi-noach]

Description

Followup to #9325. In this PR we reject a migration if submitted with same UUID and different migration_context.

As reminder, the user is allowed to supply their own migration UUIDs via vtctl ApplySchema -uuid_list='...'. This functionality is used to allow the user control and idempotency over their migrations.

UUID is a unique migration identifier. It is impossible to have any two migrations on same shard with same UUID. Hence, when one submits -uuid_list=... with an already existing UUID, their submission does not create a new migration. However, it is then also reasonable to expect that the user provides -migration_context. If the same migration is submitted twice or more, with same UUID and same migration_context, that is fine. The newer submissions are silently ignored, and this is a desired behavior that allows idempotency.

However, if the new submission uses a different migration_context (either because the user has specified one, that is different from the original one; or the user has specified none at all, in which case vtctl generates a random, unique value), then we consider this as an unintentional duplication, and as of this PR we return an error.

Here is a valid resubmission:

$ vtctlclient ApplySchema -skip_preflight -ddl_strategy='online' -migration_context="1222-2342342-423423-42" -uuid_list="4b25f49c_8709_11ec_9f54_0a43f95f28a5" -sql "alter table customer engine=innodb" commerce
4b25f49c_8709_11ec_9f54_0a43f95f28a5
$ vtctlclient ApplySchema -skip_preflight -ddl_strategy='online' -migration_context="1222-2342342-423423-42" -uuid_list="4b25f49c_8709_11ec_9f54_0a43f95f28a5" -sql "alter table customer engine=innodb" commerce
4b25f49c_8709_11ec_9f54_0a43f95f28a5

Here is an invalid one:

$ vtctlclient ApplySchema -skip_preflight -ddl_strategy='online' -uuid_list="4b25f49c_8709_11ec_9f54_0a43f95f28a6" -sql "alter table customer engine=innodb" commerce
4b25f49c_8709_11ec_9f54_0a43f95f28a6
$ vtctlclient ApplySchema -skip_preflight -ddl_strategy='online' -uuid_list="4b25f49c_8709_11ec_9f54_0a43f95f28a6" -sql "alter table customer engine=innodb" commerce
E0206 04:59:15.849989  800011 main.go:67] E0206 04:59:15.849210 vtctl.go:3282] schema change failed, ExecuteResult: {
  "FailedShards": [
    {
      "Shard": "0",
      "Err": "rpc error: code = Unknown desc = TabletManager.ExecuteQuery on zone1-0000000100 error: rpc error: code = FailedPrecondition desc = migration rejected: found migration 4b25f49c_8709_11ec_9f54_0a43f95f28a6 with different context: vtctl:84ee1103-8709-11ec-9f54-0a43f95f28a3 than submmitted migration's context: vtctl:88a0f8b4-8709-11ec-9f54-0a43f95f28a3: rpc error: code = FailedPrecondition desc = migration rejected: found migration 4b25f49c_8709_11ec_9f54_0a43f95f28a6 with different context: vtctl:84ee1103-8709-11ec-9f54-0a43f95f28a3 than submmitted migration's context: vtctl:88a0f8b4-8709-11ec-9f54-0a43f95f28a3"
    }
  ],
...

Related Issue(s)

• vtctl ApplySchema -uuid_list #9325
• Online DDL: tracking issue #6926

Checklist

• Should this PR be backported?
• Tests were added or are not required
• Documentation was added or is not required

cc @dbussink @fatih @mavenraven

[deepthi]

Wrong file? This is the 10.0.4 release notes.

[shlomi-noach]

wrong file indeed

[shlomi-noach]

The test Upgrade Downgrade Testing Query Serving / Get latest release (pull_request) keeps failing, this is unrelated to my PR.

Excerpt:

2022-02-08T09:59:09.6952407Z === RUN   TestNewUnshardedTable
2022-02-08T09:59:09.6973079Z     st_unsharded_test.go:103: 
2022-02-08T09:59:09.6974386Z         	Error Trace:	st_unsharded_test.go:103
2022-02-08T09:59:09.6975069Z         	Error:      	Not equal: 
2022-02-08T09:59:09.6985687Z         	            	expected: "[[VARCHAR(\"dual\")] [VARCHAR(\"main\")]]"
2022-02-08T09:59:09.6986286Z         	            	actual  : "[[VARCHAR(\"dual\")]]"
2022-02-08T09:59:09.6986575Z         	            	
2022-02-08T09:59:09.6987632Z         	            	Diff:
2022-02-08T09:59:09.6988374Z         	            	--- Expected
2022-02-08T09:59:09.6988897Z         	            	+++ Actual
2022-02-08T09:59:09.6990030Z         	            	@@ -1 +1 @@
2022-02-08T09:59:09.6991027Z         	            	-[[VARCHAR("dual")] [VARCHAR("main")]]
2022-02-08T09:59:09.6996097Z         	            	+[[VARCHAR("dual")]]
2022-02-08T09:59:09.6996482Z         	Test:       	TestNewUnshardedTable
2022-02-08T09:59:09.6996888Z --- FAIL: TestNewUnshardedTable (0.00s)
2022-02-08T09:59:09.6997116Z FAIL
2022-02-08T09:59:13.8529964Z FAIL	vitess.io/vitess/go/test/endtoend/vtgate/schematracker/unsharded	10.295s
2022-02-08T09:59:13.8584939Z FAIL
2022-02-08T09:59:13.8740160Z 2022/02/08 09:59:13 local.vtgate_schematracker_unsharded: saving test output to _test/20220208-095437.23387/local.vtgate_schematracker_unsharded-1.1.log
2022-02-08T09:59:13.8744938Z 2022/02/08 09:59:13 local.vtgate_schematracker_unsharded: FAILED (try 1/1) in 12s: exit status 1
2022-02-08T09:59:13.8748189Z 2022/02/08 09:59:13 local.vtgate_schematracker_unsharded: retry limit exceeded
2022-02-08T09:59:13.8749341Z 2022/02/08 09:59:13 local.vtgate_vschema: running (try 1/1)...