Add vector join table macros

[Maxxen]

Now that https://github.com/duckdb/duckdb/pull/12834 and https://github.com/duckdb/duckdb/pull/13342 have landed in core DuckDB we can make vector search a bit easier. This PR adds two table functions, implemented as table macros, to enable easy fuzzy joining of two vector datasets:

• vss_join(left_table, right_table, left_col, right_col, k, metric := 'l2sq)

  Joins the left_table and right_table by matching up to k vectors in right_col for each vector in left_col, using the metric metric (by default l2sq)

• vss_match(right_table, left_col, right_col, k, metric := 'l2sq')

  Returns up to k rows matching right_col in right_table for each input vector in left_col. Since you don't pass in a left_table to this function, you can pass in any scalar argument as left_col which allows you to use this function both in a lateral join or with a constant.

Examples:

CREATE TABLE source (name VARCHAR, s_vec FLOAT[3]);
INSERT INTO source VALUES ('alice', [5,5,5]::FLOAT[3]), ('bob', [100,120,90]::FLOAT[3]);

CREATE TABLE dest (id INTEGER, d_vec FLOAT[3]);
INSERT INTO dest SELECT row_number() over (), array_value(a,b,c) FROM range(1,10) ra(a), range(1,10) rb(b), range(1,10) rc(c);

-- Join the two tables
SELECT * FROM vss_join(source, dest, s_vec, d_vec, 3);
----
┌───────────┬──────────────────────────────────────────────┬───────────────────────────────────────┐
│   score   │                   left_tbl                   │               right_tbl               │
│   float   │    struct("name" varchar, s_vec float[3])    │  struct(id integer, d_vec float[3])   │
├───────────┼──────────────────────────────────────────────┼───────────────────────────────────────┤
│ 164.81201 │ {'name': bob, 's_vec': [100.0, 120.0, 90.0]} │ {'id': 729, 'd_vec': [9.0, 9.0, 9.0]} │
│ 165.30577 │ {'name': bob, 's_vec': [100.0, 120.0, 90.0]} │ {'id': 648, 'd_vec': [9.0, 9.0, 8.0]} │
│ 165.36626 │ {'name': bob, 's_vec': [100.0, 120.0, 90.0]} │ {'id': 720, 'd_vec': [8.0, 9.0, 9.0]} │
│       0.0 │ {'name': alice, 's_vec': [5.0, 5.0, 5.0]}    │ {'id': 365, 'd_vec': [5.0, 5.0, 5.0]} │
│       1.0 │ {'name': alice, 's_vec': [5.0, 5.0, 5.0]}    │ {'id': 364, 'd_vec': [5.0, 4.0, 5.0]} │
│       1.0 │ {'name': alice, 's_vec': [5.0, 5.0, 5.0]}    │ {'id': 356, 'd_vec': [4.0, 5.0, 5.0]} │
└───────────┴──────────────────────────────────────────────┴───────────────────────────────────────┘

-- Rank the source table rows against a constant vector
SELECT * FROM vss_match(source, [10, 10, 10]::FLOAT[3], s_vec, 5);
----
┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                                                       matches                                                                       │
│                                         struct(score float, "row" struct("name" varchar, s_vec float[3]))[]                                         │
├─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ [{'score': 8.6602545, 'row': {'name': alice, 's_vec': [5.0, 5.0, 5.0]}}, {'score': 163.09506, 'row': {'name': bob, 's_vec': [100.0, 120.0, 90.0]}}] │
└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

-- Perform a lateral join
SELECT * FROM source, vss_match(dest, s_vec, d_vec, 2);
----
┌─────────┬──────────────────────┬──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│  name   │        s_vec         │                                                                 matches                                                                  │
│ varchar │       float[3]       │                                     struct(score float, "row" struct(id integer, d_vec float[3]))[]                                      │
├─────────┼──────────────────────┼──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ bob     │ [100.0, 120.0, 90.0] │ [{'score': 164.81201, 'row': {'id': 729, 'd_vec': [9.0, 9.0, 9.0]}}, {'score': 165.30577, 'row': {'id': 648, 'd_vec': [9.0, 9.0, 8.0]}}] │
│ alice   │ [5.0, 5.0, 5.0]      │ [{'score': 0.0, 'row': {'id': 365, 'd_vec': [5.0, 5.0, 5.0]}}, {'score': 1.0, 'row': {'id': 356, 'd_vec': [4.0, 5.0, 5.0]}}]             │
└─────────┴──────────────────────┴──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘