Support explain plan for the TDS adapter

[leandrocp]

That's still a draft but it's working so you can test it locally. I'm not a SQL Server expert but looks like the result set has all the information we would need for a v1 (like the screenshot on the link below), so no need to parse XML.

I believe it's good enough for review, see #273 (comment).

Also see #231 (comment) for reference.

Wdyt?

[leandrocp]

Not sure if the order is deterministic, but looks like it's (still need to confirm on TDS code).

/edit After digging and testing, looks like that's safe.

[leandrocp]

Those function are exactly the same as used on myxql adapter, should I move those to Ecto.Adapters.SQL and put a @doc false?

[josevalim]

I think we can introduce a function called format_table in there and make it generally available. :)

[josevalim]

Looks great, awesome job! ❤️

[leandrocp]

@josevalim that's how a TDS explain looks like:

+------+----------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------+--------+--------+----------------------+----------------------+------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------+-----------------------+-----------------------+------------+-----------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+----------+----------+--------------------+
| Rows | Executes | StmtText                                                                                                                                                                                                                                                                                                                   | StmtId | NodeId | Parent | PhysicalOp           | LogicalOp            | Argument                                                                                                                           | DefinedValues                                                                                                                                                                                                                                                                            | EstimateRows | EstimateIO            | EstimateCPU           | AvgRowSize | TotalSubtreeCost      | OutputList                                                                                                                                                                                                                                                                               | Warnings | Type     | Parallel | EstimateExecutions |
+------+----------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------+--------+--------+----------------------+----------------------+------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------+-----------------------+-----------------------+------------+-----------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+----------+----------+--------------------+
|    0 |        1 | SELECT TOP(1) p0.[id], p0.[counter], p0.[title], p0.[blob], p0.[public], p0.[cost], p0.[visits], p0.[wrapped_visits], p0.[intensity], p0.[bid], p0.[uuid], p0.[meta], p0.[links], p0.[intensities], p0.[posted], p0.[author_id], p0.[inserted_at], p0.[updated_at] FROM [posts] AS p0 WHERE (p0.[title] = N'explain_test') |      1 |      1 |      0 | NULL                 | NULL                 | NULL                                                                                                                               | NULL                                                                                                                                                                                                                                                                                     |          1.0 | NULL                  | NULL                  | NULL       |  0.003283380065113306 | NULL                                                                                                                                                                                                                                                                                     | NULL     | SELECT   | false    | NULL               |
|    0 |        1 |   |--Top(TOP EXPRESSION:((1)))                                                                                                                                                                                                                                                                                             |      1 |      2 |      1 | Top                  | Top                  | TOP EXPRESSION:((1))                                                                                                               | NULL                                                                                                                                                                                                                                                                                     |          1.0 |                   0.0 | 1.0000000116860974e-7 |      16306 |  0.003283380065113306 | [p0].[id], [p0].[title], [p0].[counter], [p0].[blob], [p0].[bid], [p0].[uuid], [p0].[meta], [p0].[links], [p0].[intensities], [p0].[public], [p0].[cost], [p0].[visits], [p0].[wrapped_visits], [p0].[intensity], [p0].[author_id], [p0].[posted], [p0].[inserted_at], [p0].[updated_at] | NULL     | PLAN_ROW | false    |                1.0 |
|    0 |        1 |        |--Clustered Index Scan(OBJECT:([ecto_test].[dbo].[posts].[posts_pkey] AS [p0]), WHERE:([ecto_test].[dbo].[posts].[title] as [p0].[title]=N'explain_test'))                                                                                                                                                         |      1 |      3 |      2 | Clustered Index Scan | Clustered Index Scan | OBJECT:([ecto_test].[dbo].[posts].[posts_pkey] AS [p0]), WHERE:([ecto_test].[dbo].[posts].[title] as [p0].[title]=N'explain_test') | [p0].[id], [p0].[title], [p0].[counter], [p0].[blob], [p0].[bid], [p0].[uuid], [p0].[meta], [p0].[links], [p0].[intensities], [p0].[public], [p0].[cost], [p0].[visits], [p0].[wrapped_visits], [p0].[intensity], [p0].[author_id], [p0].[posted], [p0].[inserted_at], [p0].[updated_at] |          1.0 | 0.0031250000465661287 | 1.5809999604243785e-4 |      16306 | 0.0032830999698489904 | [p0].[id], [p0].[title], [p0].[counter], [p0].[blob], [p0].[bid], [p0].[uuid], [p0].[meta], [p0].[links], [p0].[intensities], [p0].[public], [p0].[cost], [p0].[visits], [p0].[wrapped_visits], [p0].[intensity], [p0].[author_id], [p0].[posted], [p0].[inserted_at], [p0].[updated_at] | NULL     | PLAN_ROW | false    |                1.0 |
+------+----------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------+--------+--------+----------------------+----------------------+------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------+-----------------------+-----------------------+------------+-----------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+----------+----------+--------------------+

That will look ugly when printed to a console that wraps the lines, but you can copy&paste to an editor, save to a file, or configure the console if that's possible. Anyway, I suppose that's good enough for the first version. Wdyt?

[josevalim]

Awesome job! ❤️