Dennis Gove created SOLR-8185:
---------------------------------
Summary: Add operations support to streaming metrics
Key: SOLR-8185
URL: https://issues.apache.org/jira/browse/SOLR-8185
Project: Solr
Issue Type: Improvement
Components: SolrJ
Reporter: Dennis Gove
Priority: Minor
Adds support for operations on stream metrics.
With this feature one can modify tuple values before applying to the computed
metric. There are a lot of use-cases I can see with this - I'll describe one
here.
Imagine you have a RollupStream which is computing the average over some field
but you cannot be sure that all documents have a value for that field, ie the
value is null. When the value is null you want to treat it as a 0. With this
feature you can accomplish that like this
{code}
rollup(
search(collection1, q=*:*, fl=\"a_s,a_i,a_f\", sort=\"a_s asc\"),
over=\"a_s\",
avg(a_i, replace(null, withValue=0)),
count(*),
)
{code}
The operations are applied to the tuple for each metric in the stream which
means you perform different operations on different metrics without being
impacted by operations on other metrics.
Adding to our previous example, imagine you want to also get the min of a field
but do not consider null values.
{code}
rollup(
search(collection1, q=*:*, fl=\"a_s,a_i,a_f\", sort=\"a_s asc\"),
over=\"a_s\",
avg(a_i, replace(null, withValue=0)),
min(a_i),
count(*),
)
{code}
Also, the tuple is not modified for streams that might wrap this one. Ie, the
only thing that sees the applied operation is that particular metric. If you
want to apply operations for wrapping streams you can still achieve that with
the SelectStream (SOLR-7669).
One feature I'm investigating but this patch DOES NOT add is the ability to
assign names to the resulting metric value. For example, to allow for something
like this
{code}
rollup(
search(collection1, q=*:*, fl=\"a_s,a_i,a_f\", sort=\"a_s asc\"),
over=\"a_s\",
avg(a_i, replace(null, withValue=0), as="avg_a_i_null_as_0"),
avg(a_i),
count(*, as="totalCount"),
)
{code}
Right now that isn't possible because the identifier for each metric would be
the same "avg_a_i" and as such both couldn't be returned. It's relatively easy
to add but I have to investigate its impact on the SQL and FacetStream areas.
Depends on SOLR-7669 (SelectStream)
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
