need some help making the Elixir redisgraph client work with falkorDB

[georgfaust]

There is a redisgraph client for Elixir here: https://github.com/crflynn/redisgraph-ex

It generally works, though it is old (4 years) and some things have changed, I'm about to fix that.

One thing I try to figure out is the format of the result-records.
The parsing works up to point in the code block below, but fails on a wrong assumption about what the int in the header means.
I need some kind of reference for this, the code refers to this dead link:

https://oss.redislabs.com/redisgraph/client_spec/

I write behind <-- what I understand, behind <~~ whats unclear.

# QUERY: "MATCH (p:person)-[v:visited]->(c:country) RETURN c.name, p, v"
raw_result_set: [
    [                                    <-- this is the header
      [
         1,                              <~~ what does this number indicate?
         "c.name"
      ], 
      [1, "p"], [1, "v"]], 
    [                                    <-- this is the list of solutions
      [                                  <-- this is the first solution
        [                                <-- cell in colum-0, refers to "c.name" 
          2,                             <~~ this number seems to indicate the datatype, here str
          "Japan"                        <~~ the value. as this has only two elems and is not type 7 or 8 its a scalar!?
        ],                    
        [
          8,                             <~~ this number seems to indicate a node
          [
            1,                           <-- internal node-id
            [1],                         <-- label indices, here: "person"
            [
              [
                 0,                      <-- prop-key index, here: "name"
                 2,                      <~~ data-type, here str
                 "John Doe"], 
              [1, 2, "single"], [2, 3, 33], [3, 2, "male"]
            ]
          ]
        ],
        [7, [0, 0, 1, 0, []]]            <~~ 7 seems to indicate a relation, array-field unclear
      ]
    ],
    ["Cached execution: 0", ...]
  ],
  labels: ["country", "person"],
  property_keys: ["name", "status", "age", "gender"],
  relationship_types: ["visited"]

So I think I understand everything but

• what the int in the header means
• what datatypes there are besides int, float, str
• what "cell-types" there are besides scalar, rel, node
• how the relation record is built

[gkorland]

The protocol has two modes: detailed & compact

You can read more about here: https://docs.falkordb.com/design/client_spec.html

[georgfaust]

thanks this answers all my questions, could have found that myself I think, sorry.

One thing though: Here

https://docs.falkordb.com/design/client_spec.html#reading-the-header-row

it is stated that first elem of a header elem is of ColumnType enum but it is always 1 (COLUMN_SCALAR), though the columns in the example are COLUMN_NODE, COLUMN_RELATION, COLUMN_SCALAR.

This is what broke the elixir-client. It parsed everything as scalar.

[AviAvni]

you are right see

FalkorDB/src/resultset/formatters/resultset_replycompact.c

Line 298 in ce6f659

/* Because the types found in the first Record do not necessarily inform the types

[georgfaust]

OK, but still, the docs are misleading here as you can't rely on this "backward compatibility".

Anyway, I got it working now.
I'll put some more effort in the client if we decide to use falkor in production and make a PR then.

Thanks for all the help!

[AviAvni]

the document say:

The first element is the ColumnType enum, which as of RedisGraph v2.1.0 will always be COLUMN_SCALAR. This element is retained for backwards compatibility, and may be ignored by the client unless RedisGraph versions older than v2.1.0 must be supported.

what do you want to change?

[georgfaust]

no idea, I was just confused to see the backwards compatibility advertised there and also see the code crash relying exactly on that.