add array join caveat

README.md

@@ -3,7 +3,7 @@
 [![Hex Package](https://img.shields.io/hexpm/v/chto.svg)](https://hex.pm/packages/chto)
 [![Hex Docs](https://img.shields.io/badge/hex-docs-blue.svg)](https://hexdocs.pm/chto)
 
-Uses [`Ch`](https://github.com/plausible/ch) as driver.
+Uses [Ch](https://github.com/plausible/ch) as driver.
 
 ## Installation
 
@@ -87,6 +87,29 @@ MyApp.Repo.insert_all(MyApp.Example, rows, settings: [async_insert: 1])
 MyApp.Repo.delete_all("example", settings: [allow_experimental_lightweight_delete: 1])
 ```
 
+#### Array join
+
+Ecto query doesn't `:array_join` type, so as a workaround `:inner_lateral` and `:left_lateral` are used instead for [`ARRAY JOIN`](https://clickhouse.com/docs/en/sql-reference/statements/select/array-join) and `LEFT ARRAY JOIN`, respectively:
+
+```elixir
+query =
+  "arrays_test"
+  |> join(:inner_lateral, [a], r in "arr", on: true)
+  |> select([a, r], {a.s, r.arr})
+
+{sql, _params} = Repo.to_sql(:all, query)
+
+IO.puts(sql)
+```
+
+(Prettified) output:
+
+```sql
+SELECT a0."s", a1."arr"
+FROM "arrays_test" AS a0
+ARRAY JOIN "arr" AS a1
+```
+
 #### UNION and co
 
 As of version `22.8` ClickHouse [doesn't allow](https://clickhouse.com/docs/en/sql-reference/statements/select/union) ordering or limiting combined queries:
@@ -136,11 +159,15 @@ LIMIT 2
 
 #### NULL
 
-`DEFAULT` clauses on tables are ignored when inserting RowBinary. [Please see Ch for more details and an example.](https://github.com/plausible/ch#null-in-rowbinary)
+`DEFAULT` clauses on tables are ignored when inserting RowBinary.
+
+[Ch has more details and an example.](https://github.com/plausible/ch#null-in-rowbinary)
 
 #### UTF-8
 
-Both `:binary` and `:string` Ecto schema fields are decoded as UTF-8 since Ecto doesn't allow overriding `:binary` and `:string` loaders. If that causes problems (e.g. you want to have access to the raw binary stored in `String` column), please open an issue. [See Ch for more details and an example.](https://github.com/plausible/ch#utf-8-in-rowbinary)
+Both `:binary` and `:string` Ecto schema fields are decoded as UTF-8 since Ecto doesn't allow overriding `:binary` and `:string` loaders. If that causes problems (e.g. you want to have access to the raw binary stored in `String` column), please open an issue.
+
+[See Ch for more details and an example.](https://github.com/plausible/ch#utf-8-in-rowbinary)
 
 ## Benchmarks