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system.settings

Contains information about databend system settings.

compression​

Format compression. Commonly used in stream load scenarios, default values is None. Now support:

None
Auto
Gzip
Bz2
Brotli
Zstd
Deflate
RawDeflate
Lzo
Snappy
Xz

Examples:

set compression = 'Gzip';

empty_as_default​

Format empty_as_default. Commonly used in stream load scenarios. It indicates whether the imported text is allowed to have empty values, default value is 1.

Examples：

set empty_as_default = 1;

field_delimiter​

Format field delimiter. Commonly used in stream load scenarios, default value:, .

Examples：

set field_delimiter = ',';
set field_delimiter = '|';

flight_client_timeout​

Max duration the flight client request is allowed to take in seconds. By default, it is 60 seconds.

Examples：

set flight_client_timeout = 30;

group_by_two_level_threshold​

The threshold of keys to open two-level aggregation, default value: 20000.

Examples：

set group_by_two_level_threshold = 20000;

max_block_size​

Maximum block size for reading, default value: 65536.

Examples:

set max_block_size = 65536;

max_threads​

The maximum number of threads to execute the request. By default the value is determined automatically. The value usually the same as the number of logical cpus.

Examples:

set max_threads = 8;

quoted_ident_case_sensitive​

Case sensitivity of quoted identifiers. This is related to sql_dialect default value: 1 (aka case-sensitive).

Examples:

-- set to 0

databend :) set quoted_ident_case_sensitive = 0;

databend :) create table "T"("A" int);

databend :) insert into "t"("a") values(1);

databend :) select t.a from "T";
+------+
| a    |
+------+
|    1 |
+------+

databend :) select t."a" from "T";
+------+
| a    |
+------+
|    1 |
+------+

databend :) select t.A from "T";
+------+
| A    |
+------+
|    1 |
+------+

-- set to 1

databend :) set quoted_ident_case_sensitive = 1; 
Query OK, 0 rows affected (0.03 sec)

databend :) set sql_dialect = 'MySQL';

databend :) create table t(a string);

databend :) insert into t values("a");

databend :) set sql_dialect = 'postgresql';

databend :) insert into t values("a");
ERROR 1105 (HY000): Code: 1065, displayText = error: 
  --> SQL:1:2
  |
1 | ("a")
  |  ^^^ column doesn't exist

record_delimiter​

Format record_delimiter. Commonly used in stream load scenarios, default value: "\n"

Examples:

set record_delimiter='\n';

skip_header​

Whether to skip the input header. Commonly used in stream load scenarios, default value: 0

If value greater than 0, that means the number of lines at the start of the file to skip.

Examples:

set skip_header=3;

sql_dialect​

SQL dialect, support "PostgreSQL" "MySQL" and "Hive", default value: "PostgreSQL".

set sql_dialect='PostgreSQL';

storage_read_buffer_size​

The size of buffer in bytes for buffered reader of dal. By default, it is 1MB.

Examples:

set storage_read_buffer_size = 1048576;

timezone​

The server timezone, default value: "UTC".

Examples:

set timezone = 'Asia/Shanghai';

unquoted_ident_case_sensitive​

Case sensitivity of unquoted identifiers, default value: 0 (aka case-insensitive).

Examples:

databend :) create table t(a string);

databend :) set unquoted_ident_case_sensitive=0;

databend :) create table T(a string);
ERROR 1105 (HY000): Code: 2302, displayText = Table 't' already exists.

databend :) set unquoted_ident_case_sensitive=1;

databend :) create table T(a string);

databend :) insert into t values(1);

databend :) insert into T values(2);

databend :) select * from t;
+------+
| a    |
+------+
| 1    |
+------+

databend :) select * from T;
+------+
| a    |
+------+
| 2    |
+------+