Implicit casting and resolving literal types for ARRAY when doing similarity search

[prrao87]

Consider this similarity search case where I want to return the node whose vector property is nearest to a given query vector provided by the user. I'll use the cosine similarity to demonstrate this.

import os
import shutil
import kuzu

if os.path.exists("./db"):
    shutil.rmtree("./db")

# Create database
db = kuzu.Database("./db")
conn = kuzu.Connection(db)

# Define schema
conn.execute("CREATE NODE TABLE Item(id UINT64, item STRING, price DOUBLE, vector DOUBLE[2], PRIMARY KEY (id))");

# Add data
conn.execute("MERGE (a:Item {id: 1, item: 'apple', price: 2.0, vector: cast([3.1, 4.1], 'DOUBLE[2]')})")
conn.execute("MERGE (b:Item {id: 2, item: 'banana', price: 1.0, vector: cast([5.9, 26.5], 'DOUBLE[2]')})");

# Run similarity search
res = conn.execute("MATCH (a:Item) RETURN a.item, a.price, array_cosine_similarity(a.vector, cast([6.0, 25.0], 'DOUBLE[2]')) AS sim ORDER BY sim DESC")
while res.has_next():
    row = res.get_next()
    print(row)

I want to return banana as the most similar node, based on the provided vector [6.0, 25.0], which should be the closest to the banana vector. I was able to get the above example code to work after some massaging, to return this:

['banana', 1.0, 0.9998642653091405]
['apple', 2.0, 0.9163829638139936]

Verbosity and scope for errors

The fixed-list/array type is currently a bit inconvenient and hard to use for similarity search.
It would be a lot easier if we could simply define this instead (without explicitly performing the cast)

# Add data
conn.execute("MERGE (a:Item {id: 1, item: 'apple', price: 2.0, vector: [3.1, 4.1]})")
conn.execute("MERGE (b:Item {id: 2, item: 'banana', price: 1.0, vector: [5.9, 26.5]})")

# Run similarity search
res = conn.execute("MATCH (a:Item) RETURN a.item, a.price, array_cosine_similarity(a.vector, [6.0, 25.0]) AS sim ORDER BY sim DESC")

Can this be incorporated without any breaking changes to other functionality?

[mxwli]

Probably the best way to incorporate this would be to resolve list literals to ARRAYS and allow implicit casting from ARRAYS to LISTS.

[andyfengHKU]

Probably the best way to incorporate this would be to resolve list literals to ARRAYS and allow implicit casting from ARRAYS to LISTS.

Yeah let's just implement this casting rule. Should be straight forward to do so.

[andyfengHKU]

Should be fixed in #3394