bug(duckdb): duckdb backend should add in CAST for some bind parameters

[gforsyth]

DuckDB casts bind parameters ? to strings which leads to binder errors with some queries

If we have a small tpch dataset:

import duckdb
con = duckdb.connect("tpch.ddb")
con.execute("CALL dbgen(sf=0.1)")

import ibis
con = ibis.duckdb.connect("tpch.ddb")

t = con.table('orders')
expr = t.aggregate(high_line_count=(t.o_orderpriority.case().when('1-URGENT', 1).else_(0).end().sum()

expr.execute()

raises

RuntimeError: Binder Error: No function matches the given name and argument types 'sum(VARCHAR)'. You might need to add explicit type casts.
	Candidate functions:
	sum(DECIMAL) -> DECIMAL
	sum(SMALLINT) -> HUGEINT
	sum(INTEGER) -> HUGEINT
	sum(BIGINT) -> HUGEINT
	sum(HUGEINT) -> HUGEINT
	sum(DOUBLE) -> DOUBLE

LINE 1: SELECT sum(CASE WHEN (t0.o_orderpriority = ?) ...

because our generated SQL doesn't have explicit casts:

print(expr.compile())
SELECT sum(CASE WHEN (t0.o_orderpriority = ?) THEN ? ELSE ? END) AS high_line_count 
FROM orders AS t0

we want to generate

SELECT sum(CASE WHEN (t0.o_orderpriority = ?) THEN cast(? as INTEGER) ELSE cast(? as INTEGER) END) AS high_line_count FROM orders as t0

[cpcloud]

Interestingly enough, postgres doesn't seem to have a problem with a similar query:

def test_case_agg(alltypes):
    expr = alltypes.aggregate(
        high_line_count=(
            alltypes.string_col.case().when("1", 1).else_(0).end().sum()
        )
    )
    expr.execute()

[cpcloud]

Ah that's probably because of duckdb/duckdb#2972 (comment)