Using FalkorDB as an application database (undo/redo)

[georgfaust]

Hello,

great to see that this fork exists!

I'm looking for a graph-database that I can use as an application database (create/update/query project data). One requirement I can't easily fulfill with "normal" graph databases is undo/redo.
For this I'd like to take a snapshot approach, as all other patterns are too complex.

Is it possible/feasible to just snapshot the complete redis-store on each change and restore the old state on "undo"? (I never used redis yet)

thanks for any input.

Sebastian

[gkorland]

Yes, this is a repeated request and on our priority to provide an MVCC support.
As for your question yes, Redis provides a Dump/Restore API that lets you dump a specific key and load it back. Also Redis provides a Copy and MOVE which you can use for temporary copy and then override the original key.

[georgfaust]

regarding MVCC. Do you propose an undo/redo implementation based on MVCC/timestamps rather than snapshots?

[georgfaust]

That's good to hear.
I think I'll go forward and build a POC then.
Do you know of any prior art (as this is a repeated request)?

[gkorland]

Do you know of any prior art (as this is a repeated request)?
For MVCC or Copy/Move?

[ahsf]

I meant usage of redisgraph/falkor as app-db with undo/redo.

So I just tried this out. If I understand correctly, as the graph is just one key, I just have to work on this key!? I can dump/restore the graph:

127.0.0.1:6379> GRAPH.QUERY g "CREATE (:L {foo: 1})"
...  

127.0.0.1:6379> GRAPH.QUERY g "MATCH (n:L) RETURN n"
...
  2) 1) 1) "foo"
        2) (integer) 1

127.0.0.1:6379> DUMP g
"\a\x81\x82...

127.0.0.1:6379> GRAPH.QUERY g "MATCH (n:L) SET n.foo=2 RETURN n"
...
  2) 1) 1) "foo"
        2) (integer) 2

127.0.0.1:6379> DEL g
(integer) 1

127.0.0.1:6379> RESTORE g 0 "\a\x81\x82...
OK

127.0.0.1:6379> GRAPH.QUERY g "MATCH (n:L) RETURN n"
...
  2) 1) 1) "foo"
        2) (integer) 1

COPY does not work, what am I doing wrong?

127.0.0.1:6379> COPY g save
(error) ERR not supported for this module key

There is also a "telemetry{}" key:

127.0.0.1:6379> KEYS *
1) "g"
2) "telemetry{g}"

do I have to worry about this when dumping/restoring?

[ahsf]

sorry, for the confusion. georgfaust is my private github account.

[gkorland]

#58

[georgfaust]

ok I'll go forward with using DUMP assuming I'll switch to COPY once its implemented.

[AviAvni]

can you describe more on your use case because I don't think that copying the database is a good solution

[georgfaust]

The Graph will hold application data (which is devices in rooms, connected by cables).
I need to implement undo/redo.
The easiest way to implement that is taking snapshots on each change.

gkorland mentioned that you'll implement MVCC which may offer another way to do that using timestamps. But I think it'll be way more complex.
And as the graph will not be really big, I don't think that any optimization is needed over snapshots.

[AviAvni]

Undo is just delete a node why snapshot?

[georgfaust]

one user action results in an arbitrary number of new / updated / deleted nodes and relations.

[howardshaw]

great to hear FalkorDB will provide an MVCC support.Is there any progress?Thanks.