fix: support column list before ENGINE in CREATE MATERIALIZED VIEW

[sharadgaur]

Problem

The parser fails on CREATE MATERIALIZED VIEW statements where a column list appears between the REFRESH clause and ENGINE. This is valid ClickHouse syntax produced by SHOW CREATE TABLE for refreshable materialized views (RMVs) that use an engine like Memory instead of a TO destination table.

Before (fails)

CREATE MATERIALIZED VIEW db1.config_cache_v0
REFRESH EVERY 1 SECOND
(
    `id` String,
    `name` String,
    `value` Float64
)
ENGINE = Memory
SETTINGS min_rows_to_keep = 250000, max_rows_to_keep = 500000
AS SELECT id, name, value FROM db1.config_v0

Error:

line 2:0 unexpected token: "(", expected TO or ENGINE

The parser expected either TO <table> or ENGINE = <engine> immediately after the REFRESH/SETTINGS/APPEND clauses, but ClickHouse places the column list (...) before ENGINE in its SHOW CREATE TABLE output.

After (works)

The same SQL parses correctly. The column list is stored in the new TableSchema field on CreateMaterializedView and preserved through format roundtrips.

ClickHouse syntax reference

From the ClickHouse docs:

CREATE MATERIALIZED VIEW [IF NOT EXISTS] [db.]name
  [REFRESH ...] [APPEND]
  [TO [db.]name] [(columns)] [ENGINE = engine]
  [AS SELECT ...]

When no TO clause is used (ENGINE-based MVs), ClickHouse's SHOW CREATE TABLE outputs the column definitions between REFRESH and ENGINE.

Changes

• parser/parser_view.go — Added a case p.matchTokenKind(TokenKindLParen) branch in the TO/ENGINE switch to parse the column list, then expect ENGINE after it
• parser/ast.go — Added TableSchema *TableSchemaClause field to CreateMaterializedView for column lists on ENGINE-based MVs (distinct from Destination.TableSchema which is for TO-based MVs)
• parser/format.go — Emit TableSchema before ENGINE in FormatSQL

Test

Added create_materialized_view_rmv_engine_with_columns.sql covering the full syntax: REFRESH + column list + ENGINE + SETTINGS + DEFINER + COMMENT + subquery with window function. All existing tests pass.