Hello,

after updating clickhouse from 21.2.3.15-2 to 21.3.2.5-2 I see those warnings :

 `<Warning> default.osb4_reverse.DirectoryMonitor: Structure does not match (remote: Path LowCardinality(String) ColumnLowCardinality(size = 0, UInt8(size = 0), ColumnUnique(size = 1, String(size = 1))), Value Float64 Float64(size = 0), Time UInt32 UInt32(size = 0), Date Date UInt16(size = 0), Timestamp UInt32 UInt32(size = 0), local: Path LowCardinality(String) ColumnLowCardinality(size = 0, UInt16(size = 0), ColumnUnique(size = 1, String(size = 1))), Value Float64 Float64(size = 0), Time UInt32 UInt32(size = 0), Date Date UInt16(size = 0), Timestamp UInt32 UInt32(size = 0)), implicit conversion will be done`

I think this is related to https://github.com/ClickHouse/ClickHouse/pull/19947

The only difference between remote and local I found inside this log is :

ColumnLowCardinality(size = 0, UInt8(size = 0) to
ColumnLowCardinality(size = 0, UInt16(size = 0)

But I don't see the difference between the tables.

```
SHOW CREATE TABLE default.osb4_reverse

CREATE TABLE default.osb4_reverse
(
    `Path` LowCardinality(String) CODEC(ZSTD(15)),
    `Value` Float64 CODEC(Gorilla, ZSTD(22)),
    `Time` UInt32 CODEC(DoubleDelta, ZSTD(15)),
    `Date` Date CODEC(Delta(2), ZSTD(22)),
    `Timestamp` UInt32 CODEC(ZSTD(15))
)
ENGINE = Distributed('osb4_hpc_metrics', '', 'osb4_reverse', rand())


CREATE TABLE osb4_metrics_r0.osb4_reverse
(
    `Path` LowCardinality(String) CODEC(ZSTD(15)),
    `Value` Float64 CODEC(Gorilla, ZSTD(22)),
    `Time` UInt32 CODEC(DoubleDelta, ZSTD(15)),
    `Date` Date CODEC(Delta(2), ZSTD(22)),
    `Timestamp` UInt32 CODEC(ZSTD(15))
)
ENGINE = ReplicatedReplacingMergeTree('/clickhouse/clusters/osb4_hpc_metrics/tables/{table4}/data', '{host2}')
PARTITION BY toYYYYMM(Date)
ORDER BY (Path, Time)
TTL Date + toIntervalMonth(6)
SETTINGS index_granularity = 8192
```

Any hints ?

Ralph
WriteBufferFromFile out{first_file_tmp_path};
            CompressedWriteBuffer compress{out, compression_codec};
            NativeBlockOutputStream stream{compress, DBMS_TCP_PROTOCOL_VERSION, block.cloneEmpty()};
            
            
            
            
            
            WriteBufferFromOwnString header_buf;
            writeVarUInt(DBMS_TCP_PROTOCOL_VERSION, header_buf);
            writeStringBinary(query_string, header_buf);
            context.getSettingsRef().write(header_buf);
            context.getClientInfo().write(header_buf, DBMS_TCP_PROTOCOL_VERSION);
            writeVarUInt(block.rows(), header_buf);
            writeVarUInt(block.bytes(), header_buf);
            writeStringBinary(block.cloneEmpty().dumpStructure(), header_buf);
            
            
            
            
            const StringRef header = header_buf.stringRef();
            writeVarUInt(DBMS_DISTRIBUTED_SIGNATURE_HEADER, out);
            writeStringBinary(header, out);
            writePODBinary(CityHash_v1_0_2::CityHash128(header.data, header.size), out);
            stream.writePrefix();
            stream.write(block);
            stream.writeSuffix();
            out.finalize();
            if (fsync)
                out.sync();