Add support for command SUMVAL

[arpitbbhayani]

Is your feature request related to a problem? Please describe.
There are no KV databases that support values-based aggregations. Doing a summation of integer values in the KV store would help us address a bunch of real-world use-cases

• all expenses dumped as KV, summation will give net balance quickly

Describe the solution you'd like
Introduce a command SUMVAL that does a summation of all the values and returns the result.

[golu360]

Could we compute the summation at insert/ dumping time to ensure that results of this "SUMVAL" is quick to fetch?

[arpitbbhayani]

@golu360 Yes. That would be an enhancement. The reason I was thinking of having a SUMVAL command is for in-memory ETL utilities implemented like UNIX-like PIPEs.

[golu360]

@golu360 Yes. That would be an enhancement. The reason I was thinking of having a SUMVAL command is for in-memory ETL utilities implemented like UNIX-like PIPEs.

Then similar to summation, could we also similar stuff like "AVGVAL" for average of all integer values?
I'm willing to pick up the SUMVAL piece :D

[golu360]

To summarize my solution,

1. Calculate sum of integer values on "SET"
2. Decrement on either "DELETE" or expiration.
3. Retrieve the SUM on "SUMVAL" command.

[golu360]

@arpitbbhayani I would like to work on this! :D

[arpitbbhayani]

@golu360 Let's do it on runtime; instead of keeping it pre-computed. Also, check for the encoding because not all values will be integers. The reason we are doing this is to support runtime piped operations in the future.

If you are okay with this let me know, I will assign it to you.

[golu360]

@arpitbbhayani Sounds even simpler then. Will do it on run-time.

[golu360]

@arpitbbhayani do we also need to submit a design doc for this?

[golu360]

@arpitbbhayani is this issue still open?

[arpitbbhayani]

Yes. Are you interested in picking this up?

[golu360]

Yup. Up to pick it! @arpitbbhayani

[arpitbbhayani]

Assigned it to you. Thanks for picking it up.

[golu360]

@arpitbbhayani are we only expecting integers or are we also expecting floats here?

[arpitbbhayani]

Depends on the encoding. Right now we do not support float.

Go through the code and use types and encodings we explicitly maintain. Please understand the flow before you code.

[golu360]

@arpitbbhayani @JyotinderSingh Code base has change since this was assigned. I was also thinking if we could find the sum of all values given a string pattern as well.

SUMVAL transaction.*.amount

Which returns the sum of all transaction amounts.

If no key or pattern is passed, we return the sum of all the numeric values. What are your thoughts on this?

[arpitbbhayani]

@golu360 I think we should skip this one. SUMVAL is not in our roadmap any more. we are chasing reactivity and this command does not fit into the scheme. Apologies for this. I should have closed this issue long time back.

You can find other issue to pick. thank you so much :)