Why can't I use multisearch here?

[khevans]

I'm trying to use Multisearch to combine the results of two commands. My search is:

| multisearch 
    [ search index=... sourcetype=access_combined method != OPTIONS user=khevans host=... uri_path != "/" 
        earliest=1561994601 latest=1561994640 
    | join uri type=left 
        [ search index=... sourcetype=access_combined status = 200 method != OPTIONS user=khevans 
        | fields referer referer_domain 
        | dedup referer 
        | eval uri = ifnull(substr(referer, len(referer_domain) + 1), uri) 
        | eval is_nav_out = 1 ] 
    | where isnull(is_nav_out) 
    | eval ref_uri = ifnull(substr(referer, len(referer_domain) + 1), start_uri) 
    | where ref_uri="..." 
    | eval type = "Web"] 
    [ search eventtype=... host=... api_uri != ...
        earliest=1561994601 latest=1561994640 
    | where api_user == "khevans" OR isnull(api_user) 
    | eval uri_path = api_uri . IFNULL("?" . api_uri_query, ""),
        user = IFNULL(api_user, "?"),
        type = "API" ]

I am getting this error:

Error in 'multisearch' command: Multisearch subsearches may only contain purely streaming operations (subsearch 1 contains a non-streaming command.)

According to the list of streaming commands, all of these are streaming. Additionally, when I run each search query independently, and press inspect job, both eventIsStreaming = true and resultIsStreaming = true. Why can't I run this multisearch?

[khevans · Accepted solution]

I refactored it to not use a left or an outer join, by just using a NOT [...] subsearch in the search clause.

[khevans]

To add: it seems that the left join is causing the problem, so I guess I can refactor it to not use the join. But I'm still confused as to why the Job Inspector and documentation states that it is streaming.