How to find out default values of Clickhouse server (no matter if they are in config.xml or not)?

[kriticar]

Hi,

some of the values do not exist in config.xml

For example replicated_deduplication_window_seconds.

How to see all clickhouse-server configuration options with its values, no matter if they are defined in config.xml or not?

Regards.

[Alex Zatelepin]

Specifically replicated_deduplication_window_seconds is a setting for MergeTree engines. Currently there is no easy way to query default values for this kind of settings, but you can look default values up in the source code: https://github.com/yandex/ClickHouse/blob/master/dbms/src/Storages/MergeTree/MergeTreeSettings.h#L64

[kriticar]

Thanks!

[Jack Gao]

Maybe you can use the foloowing SQL:

```

SELECT *

FROM settings

LIMIT 10

┌─name────────────────────────┬─value─────┬─changed─┬─description───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐

│ min_compress_block_size     │ 65536     │       0 │ The actual size of the block to compress, if the uncompressed data less than max_compress_block_size is no less than this value and no less than the volume of data for one mark. │

│ max_compress_block_size     │ 1048576   │       0 │ The maximum size of blocks of uncompressed data before compressing for writing to a table.                                                                                        │

│ max_block_size              │ 65536     │       0 │ Maximum block size for reading                                                                                                                                                    │

│ max_insert_block_size       │ 1048576   │       0 │ The maximum block size for insertion, if we control the creation of blocks for insertion.                                                                                         │

│ min_insert_block_size_rows  │ 1048576   │       0 │ Squash blocks passed to INSERT query to specified size in rows, if blocks are not big enough.                                                                                     │

│ min_insert_block_size_bytes │ 268435456 │       0 │ Squash blocks passed to INSERT query to specified size in bytes, if blocks are not big enough.                                                                                    │

│ max_threads                 │ 48        │       1 │ The maximum number of threads to execute the request. By default, it is determined automatically.                                                                                 │

│ max_read_buffer_size        │ 1048576   │       0 │ The maximum size of the buffer to read from the filesystem.                                                                                                                       │

│ max_distributed_connections │ 1024      │       0 │ The maximum number of connections for distributed processing of one query (should be greater than max_threads).                                                                   │

│ max_query_size              │ 262144    │       0 │ Which part of the query can be read into RAM for parsing (the remaining data for INSERT, if any, is read later)                                                                   │

└─────────────────────────────┴───────────┴─────────┴───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

```

if the changed column is 0, it means this parameter value is default.

在 2018年7月23日星期一 UTC+8下午7:51:46，kriticar写道：

[kriticar]

Thanks.