0632 — The pool sets no search_path

Context. [0631] qualified every SQL literal but left search_path at "<schema>, public", keeping the leading entry as belt-and-braces and naming the one thing it could not cover: migrate.Migration’s step funcs take (ctx, q, topicId) and reach no datastore, so a post-v1 step could not name its schema and would have resolved through the path. Meanwhile the entry carries a cost [0630] recorded and accepted: InTransaction runs the caller’s own SQL on Vulkan’s pool, so CREATE TABLE orders inside that closure lands in Vulkan’s schema rather than the caller’s.

Decision. A step’s funcs take the schema beside the topic id — func(ctx, q, schema string, topicId int64) error — and the migrate datastore passes d.Datastore.Schema at each of the four call sites. Free now: both registries are empty, and once a step ships it is immutable. With that closed, NewPostgresDatastore sets no search_path at all; the connection keeps its own default. Every Vulkan statement names its schema, so nothing of Vulkan’s depends on the path, and the caller’s statements inside InTransaction resolve the way they would on any other connection.

Consequences. [0631]‘s clause giving search_path the InTransaction job is superseded; the rest of it stands. The wart [0630] accepted is gone, and the schema lab asserts it: a caller’s CREATE TABLE inside InTransaction lands in public, and restoring the path makes that assertion fail with the table in Vulkan’s schema. Absence semantics are unchanged — a read through a missing schema is still 42P01, which the catalog reads already map, and only a write raises 3F000, which CREATE SCHEMA IF NOT EXISTS precedes. tools/compat’s guard read migration_log unqualified and now names ds.Schema; the pin flow loses its --schema public step for any two builds that both name their own schema, keeping it only for a build old enough to predate the field. The labs that assemble a table name from a variable root, and destroysystemlab’s control-plane list, had to be qualified — the path had been resolving them. Rejected: setting search_path to public alone, which is the connection default in every deployment this targets and states as configuration something Postgres already does.