Fail with a clear error when scanning a partitioned table

[simi]

Scanning a partitioned table caused an infinite hang because PostgreSQL sets relpages=-1 for relkind='p' tables. Cast to idx_t (uint64) gives pages_approx = 2^64-1, so the scanner loops over ~18 quintillion pages.

Now throws NotImplementedException at bind time with a message that includes the relation kind and table name.

---

Initial step to provide support (yes, by gracefully fail for now, better than hang IMHO) for partitioned tables, since those are broken as reported at #220.

I have plan to open set of smaller PRs to improve the situation ending with full support of partitioned tables. This is initial foundation - accepting the broken state, add friendly error and add testing infrastructure.

Example EXPLAIN (SELECT hangs):

lake D EXPLAIN (FORMAT JSON) SELECT * FROM pg.public.sales_revenues;

┌─────────────────────────────┐
│┌───────────────────────────┐│
││       Physical Plan       ││
│└───────────────────────────┘│
└─────────────────────────────┘
[
    {
        "name": "POSTGRES_SCAN",
        "children": [],
        "extra_info": {
            "Table": "sales_revenues",
            "Projections": [
                "id",
                "account_id",
                "sale_id",
                "report_id",
                "report_group_id",
                "organization_id",
                "contract_id",
                "configuration_id",
                "product_id",
                "product_asset_id",
                "asset_id",
                "base",
                "share",
                "royalty",
                "currency",
                "chain",
                "statement_id",
                "unit_amount"
            ],
            "Estimated Cardinality": "18446744073709551568"
        }
    }

pg_class returns

reporting_development=# SELECT relkind, relpages FROM pg_class WHERE relname = 'sales_revenues';
 relkind | relpages 
---------+----------
 p       |       -1

[simi]

Even patch is targeted to partitioned tables, same issue would be now for any relkind. This mapping in here is to provide nice error message only for user with safe fallback. It handles all relkinds loaded at

duckdb-postgres/src/storage/postgres_table_set.cpp

Line 32 in c89234f

WHERE attnum > 0 AND relkind IN ('r', 'v', 'm', 'f', 'p') ${CONDITION}

.

[simi]

GetScanRelpages is planned to be kept even once partitioned tables are fully supported as a guard for unexpected raw values.

[simi]

This and following GetInt64 missed the null check. Was it intended? I have added it in my change.

[simi]

I'll check on CI failures.

[staticlibs]

@simi

Just FYI, some details on local test runs: #431 (comment)