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## Summary A REQ with several `#d` values for a NIP-33 kind runs as a named, cached statement. A client resolving channel metadata for up to 128 channels sends this kind of REQ. After a few runs on a connection, Postgres can switch the statement to a generic plan, which ignores the bound values: - The `d` match stops being an index condition on `idx_events_parameterized`. - The generic plan instead walks the author's rows in `created_at` order and filters `d_tag` row by row. - The `LIMIT` is one row per requested value, so the walk never stops early. It reads every stored version of the kind, not one probe per value. This change makes three fixes: - Multi-value `#d` reads now run as unnamed statements, as tag-value matches already do (`plans_with_bound_values`), so Postgres plans every call with its values. This covers both the page `SELECT` and the `COUNT`. - The values are bound as one array (`d_tag = ANY($n)`) instead of one bind per value. The SQL text no longer changes with the number of values, which matches how channel scope is bound. - The page `SELECT` and the `COUNT` now share one `push_d_tag_filter` helper instead of two copies of the `d` predicate. **What got simpler:** - One helper replaces the duplicated `d` predicate blocks. - A `#d` read no longer produces a different statement for every value count. ### Related issue N/A. None found. ### Testing - New unit test `d_tag_sql_does_not_depend_on_value_count`: the SQL text is identical for 2 and 128 values, for both the page query and the count query. - Postgres test `value_matched_queries_are_not_cached_as_prepared_statements`, extended from the tag-value test. It runs each `#d` page and count query 6 times and asserts no `d_tag = ANY(` statement is left in `pg_prepared_statements`. It also checks the page and count results. - Mutants, each caught by the matching test: - dropping `d_tags` from `plans_with_bound_values` fails the Postgres test; - going back to a per-value `IN (...)` list fails the unit test. - Gates run at 5f71e7143b8bc4cfbecb6b4cf886be3827d54943: - `cargo fmt --check` - `cargo clippy -p buzz-db -p buzz-relay --all-targets -D warnings` - `buzz-db` unit tests: 215 passed - `scripts/postgres-test-run.sh -p buzz-relay -p buzz-db --lib --tests`: 1291 passed - `scripts/test-postgres-test-discovery.sh` - Local `EXPLAIN ANALYZE` on synthetic data (50k versions of one author's kind 39000 rows, 128 `#d` values): - With `force_custom_plan`, `d_tag = ANY(...)` is in the Index Cond on every partition. - With `force_generic_plan`, the partition holding the rows drops `d_tag` to a row filter. - On larger data the generic plan can switch to an ordered `created_at` walk. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Signed-off-by: Luke Tornquist <tornquist@squareup.com> Co-authored-by: Elrond <28d6302a099e5225b02c4155ac4236e4912603df2ab08dbfc2f4fef08ce598c8@buzz.block.builderlab.xyz> Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>