@spec alter_indexes_cql(module(), module()) :: {[String.t()], [String.t()]}

Generates ALTER TABLE ... ADD INDEX IF NOT EXISTS statements for indexes configured on the resource but not yet present in ClickHouse, and detects configured indexes whose definition differs from what's actually stored.

Returns {statements, warnings}:

• statements — safe, additive ADD INDEX IF NOT EXISTS statements for indexes that don't exist yet.
• warnings — human-readable strings for indexes that exist under the same name but with a different type or expression than configured. These are not auto-corrected: ClickHouse requires DROP INDEX + ADD INDEX to change a data-skipping index in place, and doing that automatically risks silently discarding a built index on a large table without the operator's knowledge. The warning tells you what to run manually.

Comparison of expression is best-effort: ClickHouse normalizes stored expressions (whitespace, sometimes backtick quoting, occasionally constant folding) so it may not match your DSL string byte-for-byte even when they're semantically identical. When in doubt, treat a type mismatch as authoritative and double-check expression mismatches by hand before acting on them.

@spec alter_table_cql(module(), module()) :: [String.t()]

Generates ALTER TABLE ... ADD COLUMN IF NOT EXISTS statements for attributes that exist on the resource but not yet in the table. This is a minimal schema evolution pass: it adds new columns but does not drop or alter existing ones.

Returns an empty list when the table does not exist yet (the CREATE TABLE statement handles initial creation) or when there are no new columns.

@spec create_table_cql(module()) :: String.t()

Generates the CREATE TABLE SQL for a resource.

@spec generate_resource_cql(module()) :: [String.t()]

Generates all migration statements (table creation) for a list of resources.

@spec reverse_statement(String.t()) :: String.t() | nil

Returns the inverse of a generated migration statement, or nil when it cannot be reversed.

Used as a fallback for rolling back migration files that predate down/0 support. Handles the statements this library generates:

• CREATE TABLE IF NOT EXISTS <t> (...) → DROP TABLE IF EXISTS <t>
• ALTER TABLE <t> ADD COLUMN IF NOT EXISTS <c> <type> → ALTER TABLE <t> DROP COLUMN IF NOT EXISTS <c>
• ALTER TABLE <t> ADD INDEX IF NOT EXISTS <n> (...) → ALTER TABLE <t> DROP INDEX IF NOT EXISTS <n>

Any other statement returns nil — callers must warn rather than guess.

@spec table_exists?(module(), module()) :: boolean()

Returns whether the resource table exists in ClickHouse.