docs: subqueries, derived tables, CTEs and set operators ship in 0.24.0 — correct the pages that deny it

README.md

@@ -149,7 +149,30 @@ ORDER BY sales DESC
 LIMIT 100;
 ```
 
-**Supported features:** cross-index `JOIN`s, `JOIN UNNEST`, window functions, aggregations, nested fields, geospatial queries, and more.
+Subqueries and derived tables are part of DQL too — **since engine `0.24.0`**:
+
+```sql
+-- Subquery in WHERE — IN / NOT IN, EXISTS / NOT EXISTS, a scalar comparison,
+-- or a quantified one (= ANY | SOME, <> ALL, > ALL, >= ANY, …)
+SELECT name FROM employees
+WHERE department_id IN (SELECT id FROM departments WHERE region = 'EU');
+
+-- Derived table in FROM (also valid in JOIN, nested to any depth)
+SELECT d.category, d.n
+FROM (SELECT category, COUNT(*) AS n FROM bi_events GROUP BY category) d
+WHERE d.n > 10;
+
+-- Correlated subquery — the body reads the outer row
+SELECT c.name FROM customers c
+WHERE NOT EXISTS (SELECT 1 FROM orders o WHERE o.customer_id = c.id);
+```
+
+- **Uncorrelated `WHERE` subqueries run on Elasticsearch itself**, so they work on every surface — including a plain REPL with no extensions.
+- **Derived tables and correlated subqueries run on the relational engine** — since engine `0.24.0` with arrow-extensions `0.3.4` (`softclient4es-arrow-extensions`), the same engine that executes cross-index JOINs: the REPL's default install, the JDBC driver, the ADBC driver, the Arrow Flight SQL server and Federation all carry it. A venue without it refuses the statement with a clear error instead of executing it against the first index named.
+- **Non-recursive CTEs run on that same relational engine** — a CTE reference *is* a derived table, so it carries the same venue requirement. A `WITH` clause is accepted at the top of a `SELECT` only; `WITH RECURSIVE` and CTE column lists (`WITH a (x, y) AS …`) are refused by name.
+- **Set operators run on that engine too** — `UNION` / `UNION DISTINCT`, `INTERSECT` / `INTERSECT ALL`, `EXCEPT` / `EXCEPT ALL`. `UNION ALL` is the exception: Elasticsearch answers it directly with one `_msearch`, at every venue. Branches are matched by column **position**, and the result takes the first branch's names.
+
+**Supported features:** cross-index `JOIN`s, `JOIN UNNEST`, subqueries, derived tables, CTEs, set operators, window functions, aggregations, nested fields, geospatial queries, and more.
 
 📖 **[DQL Documentation](documentation/sql/dql_statements.md)**
 
@@ -509,6 +532,9 @@ Materialized views with JOINs rely on **Elasticsearch Watcher** to automatically
 - [x] Arrow Flight SQL server (gRPC, Docker)
 - [x] ADBC driver (in-process, columnar)
 - [x] Cross-index JOINs
+- [x] Subqueries (`IN` / `EXISTS` / scalar / quantified, correlated or not) and derived tables — `0.24.0`
+- [x] Non-recursive CTEs (`WITH name AS (SELECT …)`) — `0.24.0`
+- [x] Set operators (`UNION` / `UNION DISTINCT`, `INTERSECT` / `INTERSECT ALL`, `EXCEPT` / `EXCEPT ALL`) — `0.24.0`
 - [ ] Advanced monitoring dashboard
 - [ ] Additional SQL functions
 - [ ] ES|QL bridge

documentation/client/adbc_driver.md

@@ -194,7 +194,7 @@ Multi-cluster **federation** — joining across *separate* ES clusters — is **
 
 ## What does NOT work yet
 
-Subqueries (`IN (SELECT …)`, `EXISTS`, scalar, derived tables) and CTEs (`WITH`) are not supported in the current release — they arrive in a later release. Write the JOIN explicitly instead. See the Known Limitations & Roadmap (`../sql/known_limitations.md`) for the full list.
+**Since engine `0.24.0`**, subqueries (`IN (SELECT …)` / `NOT IN`, `EXISTS` / `NOT EXISTS`, scalar and quantified comparisons) and derived tables (`FROM (SELECT …)`, `JOIN (SELECT …)`) are supported, correlated or not. **Non-recursive CTEs** (`WITH name AS (SELECT …)`) are supported too, at the top of a `SELECT`; `WITH RECURSIVE` and CTE column lists are refused by name. **Set operators** — `UNION ALL`, `UNION` / `UNION DISTINCT`, `INTERSECT` / `INTERSECT ALL`, `EXCEPT` / `EXCEPT ALL` — are supported as well; everything but `UNION ALL` runs on the relational engine this driver ships. See the Known Limitations & Roadmap (`../sql/known_limitations.md#subqueries-and-derived-tables`) for the forms that are still refused.
 
 ---
 

documentation/client/arrow_flight_sql.md

@@ -197,7 +197,7 @@ The single-cluster sidecar on this page is the free shape. Multi-cluster **feder
 
 ## What does NOT work yet
 
-Subqueries (`IN (SELECT …)`, `EXISTS`, scalar, derived tables) and CTEs (`WITH`) are not supported in the current release — they arrive in a later release. Write the JOIN explicitly instead. See the Known Limitations & Roadmap (`../sql/known_limitations.md`) for the full list.
+**Since engine `0.24.0`**, subqueries (`IN (SELECT …)` / `NOT IN`, `EXISTS` / `NOT EXISTS`, scalar and quantified comparisons) and derived tables (`FROM (SELECT …)`, `JOIN (SELECT …)`) are supported, correlated or not. **Non-recursive CTEs** (`WITH name AS (SELECT …)`) are supported too, at the top of a `SELECT`; `WITH RECURSIVE` and CTE column lists are refused by name. **Set operators** — `UNION ALL`, `UNION` / `UNION DISTINCT`, `INTERSECT` / `INTERSECT ALL`, `EXCEPT` / `EXCEPT ALL` — are supported as well; everything but `UNION ALL` runs on the relational engine this driver ships. See the Known Limitations & Roadmap (`../sql/known_limitations.md#subqueries-and-derived-tables`) for the forms that are still refused.
 
 ---
 
@@ -218,7 +218,7 @@ The Arrow Flight SQL sidecar sends one anonymous usage ping per day (no IP, no S
 
 ## Known limitations
 
-Subqueries, CTEs (`WITH`), and set operators beyond `UNION ALL` are not in R1 — and some BI tools auto-generate them. See [Known Limitations & Roadmap](../sql/known_limitations.md) for exactly what works today, what's coming in R2a, and the per-tool workaround.
+Subqueries, derived tables, non-recursive CTEs — which some BI tools auto-generate — and the `UNION` / `INTERSECT` / `EXCEPT` set operators all work since engine `0.24.0`. See [Known Limitations & Roadmap](../sql/known_limitations.md#subqueries-and-derived-tables) for exactly what works today and what is still refused.
 
 ---
 

documentation/client/bi_tools.md

@@ -37,11 +37,14 @@ Tableau's own connector documentation says that when the temp-table capabilities
 *"Tableau will attempt to generate an alternative query to retrieve the necessary results."*
 
 The probe therefore costs one failed round trip per connection and is not itself a problem. What
-follows it can be: Tableau's alternative for a source without temporary tables uses **subqueries**,
-which this release does not accept, so some interactions fail — with the same kind of clear error
-naming the statement, never a hang and never a silently wrong answer. Tableau's own documentation
-also warns that the subquery path *"can be poor, particularly with large datasets."* See the
-Honest-gap note below for what lands when.
+follows it is Tableau's alternative for a source without temporary tables, which uses **subqueries** —
+and **since engine `0.24.0`** subqueries and derived tables are accepted. (The quoted,
+fully-qualified identifiers Tableau emits alongside them have parsed since `0.23.0`; what `0.24.0`
+added is executing the derived-table wrapper.) Tableau's own documentation warns
+that the subquery path *"can be poor, particularly with large datasets"*, so it is a performance
+characteristic to watch rather than a refusal. Note that a derived table runs on the relational engine —
+since engine `0.24.0` with arrow-extensions `0.3.4` — and the JDBC driver ships it, so a Tableau
+connection has it.
 
 **A Tableau datasource customization file (`.tdc`) cannot suppress the probe.** The capability that
 would do it, `CAP_SUPPRESS_TEMP_TABLE_CHECKS`, is not among the capabilities Tableau documents for
@@ -53,10 +56,16 @@ dead end worth not walking down.
 
 ## Honest-gap note
 
-The superpower of this release is a **cross-index JOIN** that Elasticsearch can't do, and it runs best
-through explicit `JOIN … ON …` SQL — from any tool where you control the statement that is sent (Superset
-SQL Lab, DBeaver, Grafana). Some BI tools compose SQL for you: subqueries and CTEs are not in this release
-yet, and neither is the quoted, fully-qualified identifier form Tableau generates. Tableau's Custom SQL is
-not a way around that — Tableau wraps a custom query inside a `SELECT … FROM ( … )`, which is a derived
-table (Tableau's Custom SQL documentation, checked 2026-09-01). Full BI-tool subquery / CTE support is coming in the next release (Quarter 4 2026). See the
-website's Known Limitations page for the full picture.
+The superpower of this release is a **cross-index JOIN** that Elasticsearch can't do. It runs from explicit
+`JOIN … ON …` SQL and, **since engine `0.24.0`**, from the nested SQL a BI tool composes for you:
+**subqueries and derived tables are accepted**, and so is the quoted, fully-qualified identifier form
+Tableau generates.
+Tableau's Custom SQL wraps your query inside a `SELECT … FROM ( … )` (Tableau's Custom SQL documentation,
+checked 2026-09-01) — that wrapper is a derived table, which now runs on the relational engine the JDBC
+driver ships.
+
+Non-recursive **CTEs** (`WITH …`) and the **set operators** (`UNION`, `INTERSECT`, `EXCEPT`, with or
+without `ALL`) run on that same engine since `0.24.0` — a CTE reference is a derived table, and a set
+operation is its branches executed separately and combined. `UNION ALL` alone still runs on Elasticsearch,
+as it always has. See the website's Known Limitations page for the full picture, including the subquery
+and set-operator forms that are still refused by name.

documentation/client/jdbc.md

@@ -278,7 +278,7 @@ The JDBC driver supports the full SQL Gateway syntax:
 
 - **DDL** — CREATE/ALTER/DROP TABLE, pipelines, watchers, enrich policies
 - **DML** — INSERT, UPDATE, DELETE, COPY INTO
-- **DQL** — SELECT with WHERE, GROUP BY, HAVING, ORDER BY, LIMIT, UNION ALL, JOIN UNNEST, window functions
+- **DQL** — SELECT with WHERE, GROUP BY, HAVING, ORDER BY, LIMIT, set operators (`UNION [ALL]` / `INTERSECT` / `EXCEPT`), JOIN UNNEST, window functions
 - **SHOW/DESCRIBE** — Tables, pipelines, watchers, enrich policies
 
 ---
@@ -324,7 +324,7 @@ Multi-cluster **federation** — joining across *separate* ES clusters — is **
 
 ## What does NOT work yet
 
-Subqueries (`IN (SELECT …)`, `EXISTS`, scalar, derived tables) and CTEs (`WITH`) are not supported in the current release — they arrive in a later release. Write the JOIN explicitly instead. See the Known Limitations & Roadmap (`../sql/known_limitations.md`) for the full list.
+**Since engine `0.24.0`**, subqueries (`IN (SELECT …)` / `NOT IN`, `EXISTS` / `NOT EXISTS`, scalar and quantified comparisons) and derived tables (`FROM (SELECT …)`, `JOIN (SELECT …)`) are supported, correlated or not. **Non-recursive CTEs** (`WITH name AS (SELECT …)`) are supported too, at the top of a `SELECT`; `WITH RECURSIVE` and CTE column lists are refused by name. **Set operators** — `UNION ALL`, `UNION` / `UNION DISTINCT`, `INTERSECT` / `INTERSECT ALL`, `EXCEPT` / `EXCEPT ALL` — are supported as well; everything but `UNION ALL` runs on the relational engine this driver ships. See the Known Limitations & Roadmap (`../sql/known_limitations.md#subqueries-and-derived-tables`) for the forms that are still refused.
 
 ---