GitHub user merrimanr opened a pull request:
https://github.com/apache/metron/pull/702
METRON-1114: Add group by capabilities to search REST endpoint
## Contributor Comments
This PR adds a group by feature to the search REST endpoint. This PR is
fairly complex so I don't think it should be merged before a thorough
discussion and review.
The following is an intentionally simple example of how group by works.
Normally a search query would be issued and the results returned would be
similar to:
```
{
"total": 100,
"results": [
{ ... },
{ ... },
and so on
]
}
```
This PR allows a user to group results based on a field or list of fields.
For example, grouping results by a field called "fieldA" would be done by
including a "groupByFields" property:
```
{
"groupByFields":["fieldA"],
"from": 0,
"query": "*",
...
}
```
The results would then change to this form:
```
{
"total": 100,
"groupedBy": "fieldA",
"groups": [
{
"key": "value1",
"results": [
{ ... },
{ ... },
and so on
]
]
}
```
Grouping by multiple fields would just be a matter of adding a field to the
"groupByFields" list:
```
{
"groupByFields":["fieldA", "fieldB"],
"from": 0,
"query": "*",
...
}
```
The groups would then be nested based on the order they appear in the list:
```
{
"total": 100,
"groupedBy": "fieldA",
"groups": [
{
"key": "fieldA value1",
"groupedBy": "fieldB",
"groups": [
{
"key": "fieldB value1",
"results": [
{ ... },
{ ... },
and so on
]
},
{
"key": "fieldB value2",
"results": [
{ ... },
{ ... },
and so on
]
}
]
}
]
}
```
This has been verified and tested in full dev. For example, this search
query:
```
{
"groupByFields":["ip_src_addr","ip_dst_port"],
"from": 0,
"indices": [
"bro"
],
"query": "*",
"size": 5
}
```
should return search results properly grouped by those fields. The "size"
and "sort" parameters also apply to groups of search results, however the
"from" parameter does not because it doesn't make sense for that type of query
(and ES doesn't support it from what I can tell).
There are a couple of outstanding issues that we need to work through
before this gets merged:
- The group by feature is included as part of the general search feature
but having worked through the implementation, I'm not sure this is still the
best approach. There is non-trivial conditional logic that I think makes this
class harder to understand and it might make sense to move this group by query
to a separate endpoint. Interested to hear others' perspective on this since I
am so close to it.
- I also did a fair amount of refactoring in an attempt to make this class
easier to read. If that is not the case and the refactoring made it worse, let
me know.
- And finally (it has been requested in the past), I think we definitely
need more detailed documentation around this particular endpoint. I am
planning on adding some extensive documentation to this PR once we settle on an
API design approach. The alerts UI isn't quite ready for this feature so
there's no rush in getting this merged.
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You can merge this pull request into a Git repository by running:
$ git pull https://github.com/merrimanr/incubator-metron METRON-1114
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/metron/pull/702.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #702
----
commit 3650ef9aeea49d8238bf2e409ec0885120722b59
Author: merrimanr <[email protected]>
Date: 2017-08-17T14:36:05Z
initial commit
commit a4f0ba9008f2d0ee48b8bcd639558ac955249490
Author: merrimanr <[email protected]>
Date: 2017-08-17T14:40:51Z
moved group by test cases to the end
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