How to get values from workflow parallel code block?

Question

I'm trying to run two Invoke-Sqlcmd in parallel and then wait all the results.

$server1 = '...'
$server2 = '...'

workflow work {
  parallel {
    $r1 = Invoke-Sqlcmd -ServerInstance $server1 'select 1 a'
    $r2 = Invoke-Sqlcmd -ServerInstance $server2 'select 2 a'
  }
}
work
# do something with $r1 and $r2. How to access the variables here?

How to pass $server1 and $server2 to the code block?
How to get $r1 and $r2 from the parallel block?

Given that workflows are obsolescent (they're no longer supported in PowerShell Core), I suggest looking into Start-ThreadJob - see this answer. — mklement0
– mklement0, Commented Oct 28, 2019 at 23:00
You can pass in servers with a param (). Not sure how to get the results except $result = work $server1 $server2. Maybe jobs is easier. — js2010
– js2010, Commented Oct 29, 2019 at 2:17
@mklement0, I tried ThreadJob. But it doesn't work with Invoke-SqlCmd stackoverflow.com/questions/58609740/… — ca9163d9
– ca9163d9, Commented Oct 29, 2019 at 14:47
Interesting, @ca9163d9: I think the problem is a bug in Invoke-SqlCmd, as detailed in my comment on your linked question. You can work around the problem with regular child-process-based background jobs (Start-Job), but note that they have a lot more overhead than thread jobs - for long-running SQL queries that won't matter, however. — mklement0
– mklement0, Commented Oct 29, 2019 at 19:48

js2010 · Accepted Answer · 2019-10-29 03:08:34Z

1

So pass in servers with param, and return a hashtable of both results.

$server1 = '...'
$server2 = '...'

workflow work {
  param ($server1, $server2)
  parallel {
    @{r1 = Invoke-Sqlcmd -ServerInstance $server1 'select 1 a'}
    @{r2 = Invoke-Sqlcmd -ServerInstance $server2 'select 2 a'}
  }
}
$r = work $server1 $server2
$r.r1
$r.r2

edited Oct 29, 2019 at 3:08

answered Oct 29, 2019 at 2:51

js2010

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2 Comments

ca9163d9 Over a year ago

It works. However, I will use Start-ThreadJob as @mklement0 mentioned that workflow is obsolescent in the comment.

js2010 Over a year ago

I'm not sure if it's still parallel.

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