GBase 8a中一个字符占用几个字节？

GBase 8a支持GBK，UTF8，utf8mb4等字符集，所以一个字符，根据字符集不同，字符不同，占用1-4个字节。

普通字符占用1个字节

gbase> create table c1(name varchar(100));
Query OK, 0 rows affected (Elapsed: 00:00:00.11)

gbase> insert into c1 values('abcd');
Query OK, 1 row affected (Elapsed: 00:00:00.08)

gbase> select name,length(name) from c1;
+------+--------------+
| name | length(name) |
+------+--------------+
| abcd |            4 |
+------+--------------+
1 row in set (Elapsed: 00:00:00.01)

GBK字符集汉字占用2个字节

gbase> create table c2(name varchar(100)) charset=GBK;
Query OK, 0 rows affected (Elapsed: 00:00:00.10)

gbase> set names GBK;
Query OK, 0 rows affected (Elapsed: 00:00:00.00)

gbase> insert into c2 values('中国');
Query OK, 1 row affected (Elapsed: 00:00:00.07)

gbase> select * from c2;
+--------+
| name   |
+--------+
| 中国   |
+--------+
1 row in set (Elapsed: 00:00:00.01)

gbase> select name,length(name) from c2;
+--------+--------------+
| name   | length(name) |
+--------+--------------+
| 中国   |            4 |
+--------+--------------+
1 row in set (Elapsed: 00:00:00.00)

UTF8字符集普通汉字占用3个字节

gbase> set names UTF8;
Query OK, 0 rows affected (Elapsed: 00:00:00.00)

gbase> insert into c1 values('中国');
Query OK, 1 row affected (Elapsed: 00:00:00.08)

gbase> select name,length(name) from c1;
+--------+--------------+
| name   | length(name) |
+--------+--------------+
| abcd   |            4 |
| 中国   |            6 |
+--------+--------------+
2 rows in set (Elapsed: 00:00:00.01)

生僻汉字和Emoji占用4个字节

gbase> create table c3(name varchar(100)) charset=UTF8MB4;
Query OK, 0 rows affected (Elapsed: 00:00:00.11)

gbase> set names utf8mb4;
Query OK, 0 rows affected (Elapsed: 00:00:00.00)

gbase> insert into c3 values('😃');
Query OK, 1 row affected (Elapsed: 00:00:00.08)

gbase> select name,length(name) from c3;
+------+--------------+
| name | length(name) |
+------+--------------+
| 😃     |            4 |
+------+--------------+
1 row in set (Elapsed: 00:00:00.00)