flightsql/driver: tx.QueryContext with no args appears to ignore active transaction handle

[wjywbs]

Describe the bug, including details regarding any error messages, version, and platform.

I was using GPT-5.3-Codex to generate code for querying db using Arrow Flight SQL, and it found a possible bug in the arrow-go client. All the text below and the title is generated by Codex.

Description
I’m seeing inconsistent transaction behavior in github.com/apache/arrow-go/v18/arrow/flight/flightsql/driver (v18.5.1) when using database/sql.

In a transaction, queries with parameters behave correctly, but zero-argument tx.QueryRowContext(...) appears to execute outside the transaction.

This is easy to reproduce with tx-local DDL:

1. BEGIN
2. CREATE TABLE tx_tmp (id BIGINT, v BIGINT)
3. INSERT INTO tx_tmp VALUES (1, 10)
4. tx.QueryRowContext(ctx, "SELECT COUNT(*) FROM tx_tmp") -> fails (table does not exist)
5. tx.QueryRowContext(ctx, "SELECT COUNT(*) FROM tx_tmp WHERE id >= ?", 1) -> works (returns 1)

Expected:

• Both queries run in the same active transaction and return 1.

Actual:

• Zero-arg query can behave as if it is outside the tx (cannot see uncommitted DDL/data).

From code inspection, this may be because Connection.QueryContext uses c.client.Execute(...) directly and does not branch on c.txn, while prepared-statement paths do use txn.Prepare(...).

Likely affected code:

• arrow/flight/flightsql/driver/driver.go
  • Connection.QueryContext(...)
  • compare with Connection.PrepareContext(...) transaction handling

Suggested fix:

• In Connection.QueryContext, when c.txn != nil && c.txn.ID().IsValid(), execute through transaction handle (or force transaction-bound prepared execution path), so no-arg tx queries stay transaction-scoped.

Suggested tests:

• Add regression test for tx-local DDL visibility with:
  • zero-arg tx.QueryRowContext(...)
  • parameterized tx.QueryRowContext(..., arg)
• Both should see uncommitted tx-local table/data consistently.

Component(s)

Integration, Other