docs: add Redis ADBC integration guide

README.md

@@ -22,6 +22,9 @@ Full documentation, including installation, driver setup, the `ATTACH` storage l
 
 **[https://query.farm/products/extensions/adbc_scanner](https://query.farm/products/extensions/adbc_scanner)**
 
+For Redis driver installation, reads, local joins, and autocommit writes, see
+the [Redis ADBC integration guide](docs/redis.md).
+
 ## Installation
 
 ```sql

docs/redis.md

@@ -0,0 +1,88 @@
+# Redis through ADBC
+
+The [Redis ADBC driver](https://github.com/alberttwong/redis-adbc-driver)
+provides SQL queries and Arrow ingestion over Redis HASHes and Redis Search.
+It works with `adbc_scanner` through the normal `TYPE adbc` attachment.
+
+## Install the driver
+
+Download and unpack the native driver archive for your platform from the
+[driver releases](https://github.com/alberttwong/redis-adbc-driver/releases).
+Install its manifest with `./install.sh --user`, keeping the unpacked library
+in place. Alternatively, use the absolute library path in the `driver` option
+below (`.so` on Linux, `.dylib` on macOS).
+
+A Python release wheel also bundles the native driver. Installing the wheel
+alone does not install a manifest for DuckDB; run
+`python -m adbc_driver_redis install-manifest --user` afterward. See the
+[driver installation guide](https://github.com/alberttwong/redis-adbc-driver/blob/main/docs/python-integrations.md#install-and-discover-the-driver).
+
+The server must provide Redis Search (the Query Engine). Redis Cloud, Redis
+Software, and Redis 8.x with Search are supported by the driver. Redis Flex,
+Valkey, and Redis 7.2 derivatives are unsupported. Use `rediss://` for TLS and
+give the Redis user the permissions described in the
+[driver's ACL guide](https://github.com/alberttwong/redis-adbc-driver#acl-users).
+
+## Read and join
+
+```sql
+INSTALL adbc_scanner FROM community;
+LOAD adbc_scanner;
+
+ATTACH 'redis://localhost:6379/0' AS r
+    (TYPE adbc, driver 'redis', READ_ONLY);
+
+-- public is the driver's default schema.
+SELECT * FROM r.public.orders LIMIT 10;
+
+-- Send SQL explicitly to the Redis driver's query engine.
+SELECT * FROM adbc_scan('r',
+    'SELECT country, COUNT(*) AS n FROM public.orders GROUP BY country');
+
+-- DuckDB plans the local join.
+SELECT o.id, o.country, c.label
+FROM r.public.orders AS o
+JOIN (VALUES ('US', 'United States'), ('CA', 'Canada')) AS c(code, label)
+    ON o.country = c.code;
+
+DETACH r;
+```
+
+These queries assume an existing driver-managed `public.orders` table with
+`id` and `country` columns. Arbitrary existing HASHes need to be copied or
+adopted with the driver's `redis-adbc` utility before they appear as tables.
+The driver can configure a different default schema; use its actual schema.
+`READ_ONLY` rejects writes through the attachment; Redis ACLs control server
+permissions independently.
+
+## Write in autocommit
+
+Use a dedicated database for this example. Run without a surrounding `BEGIN`.
+
+```sql
+ATTACH 'redis://localhost:6379/0' AS r (TYPE adbc, driver 'redis');
+
+CALL adbc_execute('r',
+    'CREATE TABLE public.duckdb_adbc_example (id integer, country text)');
+SELECT * FROM adbc_insert(
+    'r', 'duckdb_adbc_example',
+    (SELECT * FROM (VALUES (1, 'US'), (2, 'CA')) AS source(id, country)),
+    mode := 'append'
+);
+SELECT * FROM r.public.duckdb_adbc_example ORDER BY id;
+
+CALL adbc_execute('r', 'DROP TABLE public.duckdb_adbc_example');
+DETACH r;
+```
+
+The Redis driver does not implement multi-statement transactions. Writes inside
+`BEGIN` fail; `ROLLBACK` cannot undo autocommit writes. A failing autocommit
+statement can leave partial changes. Current `adbc_scanner` builds also support
+`INSERT INTO r.public.t` and `CREATE TABLE r.public.t AS SELECT ...` outside
+explicit transactions; older builds require `adbc_insert` / `adbc_execute`.
+
+SQL passed to `adbc_scan` executes in the Redis driver, which can push supported
+predicates and aggregates to Search. SQL over an attached table is planned by
+DuckDB; inspect `EXPLAIN` and measure your query before assuming full remote
+execution. For driver capabilities and limitations, see its
+[DuckDB integration guide](https://github.com/alberttwong/redis-adbc-driver/blob/main/docs/duckdb.md).