[quinnj-bot]

What

Postgres.Cursor (what Postgres.cursor returns) now subtypes DBInterface.Cursor.

Why

Code that dispatches on the abstract cursor type skipped streaming Postgres cursors. The motivating case is JuliaServices/StructUtils.jl#95, which reads and writes any DBInterface.Cursor as an array of its rows. With both changes, query results stream straight into JSON:

Postgres.transaction(conn) do tx
    JSON.json(io, Postgres.cursor(tx, "SELECT id, name FROM users"; fetchsize=1000); jsonlines=true)
end

Today JSON.json on a cursor writes the cursor's fields, starting with its whole Connection. Postgres.Result (from DBInterface.execute) is an AbstractVector of rows and already writes as an array of row objects, so it is unaffected. DBInterface defines no methods on DBInterface.Cursor that change this package's behavior.

Verification

• New assertion in the "Cursor Streaming" testset: cur isa DBInterface.Cursor.
• Full suite with the Docker integration tests (POSTGRES_REQUIRE_INTEGRATION=true, postgres:16) on Julia 1.12.6: 9242/9242.
• End to end with StructUtils#95 and JSON 1.13 against PostgreSQL 16.

🤖 Generated with Claude Code