Stop sorting keys.

[betawaffle]

I don't know why this was done originally, but sorting the keys breaks most multi-dimensional metrics. The test cases seem to have been very lucky.

[jaqx0r]

The sorting was to make the tests stable :) I can improve the comparison
in the tests only to avoid the sort.

Can you show me an example that is breaking so I can test correctness?

On 10 June 2015 at 01:30, Andrew Hodges notifications@github.com wrote:

I don't know why this was done originally, but sorting the keys breaks

most multi-dimensional metrics. The test cases seem to have been very lucky.

You can view, comment on, or merge this pull request online at:

#4
Commit Summary

• Stop sorting keys.

File Changes

• M testdata/rsyncd.json
  https://github.com/google/mtail/pull/4/files#diff-0 (12)
• M vm/parser.y https://github.com/google/mtail/pull/4/files#diff-1
  (2)
• M vm/vm.go https://github.com/google/mtail/pull/4/files#diff-2
  (2)

Patch Links:

• https://github.com/google/mtail/pull/4.patch
• https://github.com/google/mtail/pull/4.diff

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#4.

[betawaffle]

Sure.

• Define a metric with two (or more) dimensions, in my case, the keys were page and edge.
• Use values that sort differently the keys, in my case, page was a number like 1234567 and edge was a word like comments.

Both the keys and the values were being sorted before being zipped together, causing edge to be matched with 1234567 and page to be matched with comments.

counter my_multidimensional_metric by page, edge

/some pattern with an (?P<edge>\w+) and a (?P<page>\d+)/ {
  my_multidimensional_metric[$page][$edge]++
}

The above code results in a metric that looks like this:

# TYPE my_multidimensional_metric counter
my_multidimensional_metric{edge="1234567",page="comments",prog="example.mtail",instance="example.com"} 1 1433934627

[jaqx0r]

Ohhh that is a total facepalm. Thanks!

On 10 June 2015 at 21:12, Andrew Hodges notifications@github.com wrote:

Sure.

• Define a metric with two (or more) dimensions, in my case, the keys
  were page and edge.
• Use values that sort differently the keys, in my case, page was a
  number like 1234567 and edge was a word like comments.

Both the keys and the values were being sorted before being zipped
together, causing edge to be matched with 1234567 and page to be matched
with comments.

counter my_multidimensional_metric by page, edge

/some pattern with an (?P\w+) and a (?P\d+)/ {
my_multidimensional_metric[$page][$edge]++
}

The above code results in a metric that looks like this:

TYPE my_multidimensional_metric counter

my_multidimensional_metric{edge="1234567",page="comments",prog="example.mtail",instance="example.com"} 1 1433934627

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#4 (comment).