Check table metadata in zookeeper

Check table metadata in zookeeper.

Compare table metadata of different replicas in zookeeper

Check if a table is consistent across all zookeeper replicas. From each replica, returns metdadata, columns, and is_active nodes. Checks whether each replica’s value matches the previous replica’s value, and flags any mismatches (looks_good = 0).

SELECT
    *,
    if(
        prev_name = name AND name != 'is_active',
        prev_value = value,
        1
    ) AS looks_good
FROM (
    SELECT
        name,
        path,
        ctime,
        mtime,
        value,
        lagInFrame(name)  OVER w AS prev_name,
        lagInFrame(value) OVER w AS prev_value
    FROM system.zookeeper
    WHERE (path IN (
        SELECT arrayJoin(groupUniqArray(if(path LIKE '%/replicas', concat(path, '/', name), path)))
        FROM system.zookeeper
        WHERE path IN (
            SELECT arrayJoin([zookeeper_path, concat(zookeeper_path, '/replicas')])
            FROM system.replicas
            WHERE table = 'test_repl'
        )
    )) AND (name IN ('metadata', 'columns', 'is_active'))
    WINDOW w AS (ORDER BY name = 'is_active', name ASC, path ASC
                 ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)
)

Returns a table’s create_table_query, and the last time the table’s metadata was modified

SELECT metadata_modification_time, create_table_query
FROM system.tables
WHERE name = 'test_repl'
Last modified 2026.02.25: Added explanations for multiple Useful Queries pages, fixed some non-functional queries (7840c77)