Fix should allow column list before ENGINE in CREATE MATERIALIZED VIEW

[sharadgaur]

Problem

Two issues with CREATE MATERIALIZED VIEW parsing:

1. Column list before ENGINE fails (new syntax support)

ClickHouse SHOW CREATE TABLE for refreshable materialized views with ENGINE (e.g. Memory) outputs the column list between REFRESH and ENGINE:

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

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

After: Parses correctly. Column list stored in CreateMaterializedView.TableSchema.

2. DEPENDS ON with multiple tables fails (bug fix)

CREATE MATERIALIZED VIEW db1.mv
REFRESH EVERY 5 MINUTE
DEPENDS ON db1.mv_a, db1.mv_b
ENGINE = Memory
AS SELECT 1

Before: expected <ident> or <string>, but got ","

After: Parses correctly. Both tables captured in DependsOn slice.

Root cause: The comma token was not consumed before parsing the next table identifier in the DEPENDS ON loop. The query parser (parser_query.go) has the correct pattern (consumeToken() after matching comma), but the view parser was missing it.

ClickHouse syntax reference

CREATE MATERIALIZED VIEW [IF NOT EXISTS] [db.]name [ON CLUSTER cluster]
  [REFRESH EVERY|AFTER interval [OFFSET interval]]
  [RANDOMIZE FOR interval]
  [DEPENDS ON [db.]name [, [db.]name [, ...]]]
  [SETTINGS name = value [, ...]]
  [APPEND]
  [TO [db.]name] [(columns)] [ENGINE = engine]
  [EMPTY]
  [DEFINER = { user | CURRENT_USER }] [SQL SECURITY { DEFINER | NONE }]
  AS SELECT ...
  [COMMENT 'comment']

Changes

File	Change
parser/parser_view.go	Handle ( as column list before ENGINE; add consumeToken() for comma in DEPENDS ON
parser/ast.go	Add TableSchema *TableSchemaClause to CreateMaterializedView
parser/format.go	Emit TableSchema before ENGINE
parser/walk.go	Traverse TableSchema in Walk

Tests

Added 2 test fixtures:

• create_materialized_view_rmv_engine_with_columns.sql — REFRESH + column list + ENGINE + SETTINGS + DEFINER + COMMENT + subquery
• create_materialized_view_rmv_depends_on_multi.sql — REFRESH + multi-table DEPENDS ON + ENGINE

Validated 21 MV syntax variants covering all combinations. All existing tests pass.

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Reviewed commit: 41671648a4

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