topic Re: Split is converting my empty strings back into null? in Splunk Search

Split is converting my empty strings back into null?

nick405060 — Tue, 28 Jan 2020 00:36:45 GMT

This query kills morejunk even though it should NOT be doing so:

| makeresults | eval a="1 2" | eval b="junk" | append [| makeresults | eval b="morejunk"] | fillnull value="" | eval a=split(a," ") | mvexpand a | table a b

It works if you move the fillnull after the split. I am very aware mvexpand removes null values.

This is a bug, right? There's no way that split is meant to return null for any STRING value it can't split, right? Because otherwise it would be effectively mean death to use split in conjunction with mvexpand without a fillnull directly in between them.

Re: Split is converting my empty strings back into null?

jbrocks — Sat, 01 Feb 2020 17:41:06 GMT

I think you need to rename the "a", because you define a new by eval and the refer to the old a. Did you try | eval c=split(a, " ")?

Re: Split is converting my empty strings back into null?

to4kawa — Sat, 01 Feb 2020 22:34:08 GMT

mvexpand OR stats count by multivalue remove null values.
They are useful. so, I think It' not a bug.

Conversely, do you have problems removing Null?
If it is a known problem, I think fillnull can be used.

Just as index=hoo your_field!= "" and index= foo NOT your_field="" are different, the treatment of NULL in Statistics and Events seems to be different.
In Events
Null means there are no fields.
In Statistics
Null means that the field has no value.
How do you think this?

| makeresults
| eval z=""
| fields z a b c
| fillnull a b c z

However, this result is...

Re: Split is converting my empty strings back into null?

nick405060 — Mon, 03 Feb 2020 20:54:23 GMT

I downvoted this post because I don't think you read the question. The entire point is that split is converting empty strings into null values even when you use fillnull beforehand...

Re: Split is converting my empty strings back into null?

nick405060 — Mon, 03 Feb 2020 20:57:14 GMT

You can eval a field back into itself. This should not be the problem here.

Also I tried evaling to a new field and then mvexpanding that new field per your suggestion, and it is still the same issue.

Re: Split is converting my empty strings back into null?

nick405060 — Thu, 19 Mar 2020 17:26:08 GMT

Hi Nick,

Another quick update:
Engineering confirmed and is now planning to have the fix for SPL-182511 in 8.0.4+ (this can still change).

Please let me know if there is any further questions.

Maarten Hoogcarspel
Splunk Technical Support