Use the query lock hint when joining tables

[aidanharan]

When you perform a query using locking and a left-join, the lock is used in both the FROM and LEFT OUTER JOIN portions of the query:

ActiveRecord: Person.lock(true).left_joins(:readers).load
SQL: SELECT [people].* FROM [people] WITH(UPDLOCK) LEFT OUTER JOIN [readers] WITH(UPDLOCK) ON [readers].[person_id] = [people].[id]

However, when you use the same query with a inner-join, the lock is not used in the INNER JOIN portion of the query:

ActiveRecord: Person.lock(true).joins(:readers).load
SQL: SELECT [people].* FROM [people] WITH(UPDLOCK) INNER JOIN [readers] ON [readers].[person_id] = [people].[id]

This change will apply the lock hint to the inner-joins.

I came across this issue as we are trying to use NOLOCK hints on queries containing joins.

ActiveRecord: Person.lock('WITH(NOLOCK)').joins(:readers).load
Before change SQL: SELECT [people].* FROM [people] WITH(NOLOCK) INNER JOIN [readers] ON [readers].[person_id] = [people].[id]
After change SQL: SELECT [people].* FROM [people] WITH(NOLOCK) INNER JOIN [readers] WITH(NOLOCK) ON [readers].[person_id] = [people].[id]

[metaskills]

Love the work here, thanks!

[metaskills]

Just pushed v5.1.6 to rubygems. Again, thanks!!!