Enable and disable the examplers storage with flag

[hiteshwani29]

PR closes #5789

• I added CHANGELOG entry for this change.
• Change is not relevant to the end user.

Changes

Added --tsdb.enable-exemplar-storage flag to enable examples storage. For enabling examples storage we should enable this tsdb.enable-exemplar-storage flag and set value of tsdb.enable-exemplar-storage > 0. To disable examples storage set value of tsdb.enable-exemplar-storage <=0 and disable tsdb.enable-exemplar-storage flag.

Verification

Tested locally

[matej-g]

Thanks for this @hiteshwani29, but wonder in line with comment #5789 (comment), do we necessarily need a new flag?

[hiteshwani29]

Yes @matej-g even if we pass --tsdb.max-exemplars=0 it will still enables exempler storage because we are hardcoding this EnableExemplarStorage to true.

If we check this tsdb code https://github.com/prometheus/prometheus/blob/main/tsdb/head_append.go#L56
and https://github.com/prometheus/prometheus/blob/main/tsdb/head_append.go#L144

we can figure out that it enables exempler storage if max-exemplers is <= 0 or EnableExemplarStorage is true
Right now this EnableExemplarStorage is always true so it enables exempler storage even if we pass max-exempler value <=0

[GiedriusS]

Yes @matej-g even if we pass --tsdb.max-exemplars=0 it will still enables exempler storage because we are hardcoding this EnableExemplarStorage to true.

If we check this tsdb code https://github.com/prometheus/prometheus/blob/main/tsdb/head_append.go#L56 and https://github.com/prometheus/prometheus/blob/main/tsdb/head_append.go#L144

we can figure out that it enables exempler storage if max-exemplers is <= 0 or EnableExemplarStorage is true Right now this EnableExemplarStorage is always true so it enables exempler storage even if we pass max-exempler value <=0

I concur with @matej-g. It looks like setting EnableExemplarStorage: maxExemplars > 0 should do the job, no? 🤔

[hiteshwani29]

Workaround you suggested will not work. With EnableExemplarStorage: false will always disable exemplar storage. we can't able to enable or disable it by only passing the values to the max-exemplars. We need this flag set to enable or disable exemplar storage.

…

On Thu, 16 Mar 2023 at 16:02, Giedrius Statkevičius < ***@***.***> wrote: Yes @matej-g <https://github.com/matej-g> even if we pass --tsdb.max-exemplars=0 it will still enables exempler storage because we are hardcoding this EnableExemplarStorage to true. If we check this tsdb code https://github.com/prometheus/prometheus/blob/main/tsdb/head_append.go#L56 and https://github.com/prometheus/prometheus/blob/main/tsdb/head_append.go#L144 we can figure out that it enables exempler storage if max-exemplers is <= 0 or EnableExemplarStorage is true Right now this EnableExemplarStorage is always true so it enables exempler storage even if we pass max-exempler value <=0 I concur with @matej-g <https://github.com/matej-g>. That sounds like a bug in Prometheus logic. Either way, then we could workaround this by setting EnableExemplarStorage: false and that's it? Then we won't need another flag? — Reply to this email directly, view it on GitHub <#6216 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ALGGVYQFE574OZKIPKEUL43W4LT25ANCNFSM6AAAAAAV3USYFQ> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[GiedriusS]

See my edited message 😄 @hiteshwani29

[hiteshwani29]

Yeah 😄 @GiedriusS
Agreed to enable exemplar storage EnableExemplarStorage: true maxExemplars > 0 will do the job
But to disable storage we need to set EnableExemplarStorage: false. We will not able to disable exemplars storage with EnableExemplarStorage: true maxExemplars < 0 with current changes. We should toggle this value as per need. We should not hardcode it to true.

[hiteshwani29]

@GiedriusS @matej-g @yeya24 Any update on this PR?

[hiteshwani29]

Did the suggested changes @GiedriusS

[GiedriusS]

🎖️

[fpetkovski]

Thanks 👍