Question

I have following data

| From | To |
+------+----+
|    1 |  2 |
|    2 |  3 |
|    2 |  4 |
|    5 |  1 |
|    6 |  5 |
|    5 |  7 |
+------+----+

Now I would like to query my data with CTE enhanced select, like

DECLARE @start INT;
SET @start = 1;
DECLARE @depth INT;
SET @depth = 1;

WITH
[Recursive] AS
(
    SELECT
        1 as [level],
        *
    FROM    [dbo].[myTable]
    WHERE   @start IN ([From], [To])
    UNION ALL
    SELECT
        t1.[level] + 1,
        t2.*
    FROM    [Recursive] t1
    JOIN    [dbo].[myTable] t2
        ON    t1.[level] < @depth
        AND
        (
            t1.[From] IN (t2.[From], t2.[To])
            OR t1.[To] IN (t2.[From], t2.[To])
        )
)
SELECT DISTINCT
    [From],
    [To]
FROM    [Recursive]

With this small test-data the performance is quite ok – but when increasing the data and depth the execution gets really bad (caused by multiple-column join).

What is the correct statement for such a task?

Answer 1

As I use C# on my client-side, I ended up pulling all the data to the client and to the graph-calculation-stuff in C#. It’s way more performant and as memory-footprint is not the problem, I am happy with that 🙂