Support vtctl OnlineDDL <keyspace> show <context>

[shlomi-noach]

Backport

NO

Status

DRAFT

Description

This adds support for vtctl OnlineDDL <keyspace> show <context>, to show all migrations that share the same context. For example, someone runs vtctl ApplySchema -ddl_strategy "gh-ost" -sql "multiple; queries; here;"

Each DDL query in the above gets its own UUID, the migration ID used for tracking that migration. But also, all of the migrations in that command have the same migration context, some arbitrary string that identifies them.

BTW vtctl ApplySchema... does not actually return that migration context (yet?). It's known internally to whatever service issued the migration, and can be used to track status for those migrations as a whole. We may expose the migration context to the user in the future.

Related Issue(s)

#6926 (comment)
followup to #7082

Todos

• Tests
• Documentation

Impacted Areas in Vitess

List general components of the application that this PR will affect:

• Query Serving
• VReplication
• Cluster Management
• Build

[shlomi-noach]

Actually there's a SQL injection case here; I need to parse/bind the query first.

[shlomi-noach]

I added a new convenience function in sqlparser:

func ParseAndBind(in string, binds ...*querypb.BindVariable) (query string, err error) 

which allows for quickly creating a binded query, e.g.:

query, err := ParseAndBind("select * from tbl where name=%a", sqltypes.StringBindVariable("it's me"))

And with that I fixed SQL injection concerns in vtctl/vtctl.go.

[ajm188]

lgtm