Syntax overview

BtrQL source is a file of headers, symbols definitions and top level queries and procedure calls.

Syntax failures and migration guidance are reported through Diagnostics and errors.

Grammar

This grammar map is compact, not the full formal grammar. The extension-column surface below is currently implemented by the PostgreSQL and ClickHouse C# prototypes.

file              ::= header* item*header            ::= using_header | schema_header | import_headerusing_header      ::= "using" schema_nameschema_header     ::= "schema" schema_nameimport_header     ::= "import" module_path [ "{" import_alias ("," import_alias)* "}" ]import_alias      ::= ident [ "->" ident ]​item              ::= query | dml | call_stmt | object_decl | reusable_decl | routine_decl | macro_declreusable_decl     ::= "val" ident "=" expr                   | "type" ident "=" type_expr                   | extension_declextension_decl    ::= "extension" table_type "{" extension_member* "}"extension_member  ::= method_decl | column_declmethod_decl       ::= "method" ident [ table_param_group ] [ scalar_param_group ] [ "=>" table_type ] "=" relationcolumn_decl       ::= "column" ident [ ":" scalar_type ] "=" exprtable_param_group ::= "(" ident ":" table_type ("," ident ":" table_type)* ")"scalar_param_group ::= "(" ident ":" scalar_type ("," ident ":" scalar_type)* ")"​object_decl       ::= "table" ident table_shape                   | "view" ident "=" relation                   | "materialized view" ident "=" relation                   | [ "unique" ] "index" ident "on" ident "(" expr_list ")" [ "where" expr ]​routine_decl      ::= "function" ident "(" param_list? ")" "=" expr                   | "table function" ident "(" param_list? ")" "=>" table_shape "=" relation                   | "procedure" ident "(" param_list? ")" "{" proc_stmt* "}"​query             ::= relationrelation          ::= relation_source relation_step*relation_source   ::= ident | qualified_ident | "(" relation ")" | row_literal | table_literalrelation_step     ::= ".as(" ident ")"                   | ".select(" projection_list ")"                   | ".where(" expr ")"                   | ".addColumn(" projection_list ")"                   | ".removeColumn(" column_list ")"                   | ".orderBy(" sort_list ")"                   | ".limit(" expr ")"                   | ".offset(" expr ")"                   | ".distinct"                   | ".distinctOn(" expr_list ")"                   | ".group { by(" expr_list ") aggregate(" projection_list ")" [ " having(" expr ")" ] " }"                   | join_step | apply_step | set_step | qualify_stepprojection_list   ::= projection ("," projection)*projection        ::= expr [ "->" ident ]join_step         ::= "." join_name "(" relation " on " expr ")"apply_step        ::= ".crossApply(" relation ")" | ".outerApply(" relation ")"set_step          ::= "." set_name "(" relation ")"qualify_step      ::= ".qualify(" expr ")"​dml               ::= relation ".insert(" ident ")"                   | relation ".update { into " ident " set(" assignment_list ") }"                   | relation ".delete"                   | relation ".mergeInto(" ident ") { ... }"                   | dml ".returning(" projection_list ")"​expr              ::= literal | ident | qualified_ident | function_call                   | unary_expr | binary_expr | case_expr | window_expr | "(" expr ")"​

column recipe and addColumn[Type] are removed from the C# prototype grammar and receive targeted migration diagnostics. A bare extension-column request is an ordinary scalar expression whose output alias is the extension member name. Earlier aliases in the same select or addColumn are visible only to later projections.