Differences between ClickHouse and YQL dialects of SQL

Terminology

  • A ClickHouse ARRAY is called a List in YQL, with the same naming difference applying to most functions used to handle them.
  • The ClickHouse ARRAY JOIN operation is called FLATTEN BY in YQL.
  • From the YQL perspective, the data type of both physical and nested (Nested in ClickHouse) logical tables is List<Struct<...>>. In YQL, container data types can be combined in any way.

Syntax

  • In ClickHouse, you can assign an alias to almost any part of an expression using AS and then reference that alias in another part of the query. In contrast, YQL is very strict about the scope of columns in different parts of a SELECT statement.
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