GBase 8a数据库集群支持global Hash索引，用于精确查询。为了方便释放空间，提供了key_dc_size参数，如果该参数和每次加载的数据量出现匹配，将会很容易出现抖动。
目录导航
环境
三个节点的集群
[gbase@localhost ~]$ gcadmin
CLUSTER STATE: ACTIVE
VIRTUAL CLUSTER MODE: NORMAL
=============================================================
| GBASE COORDINATOR CLUSTER INFORMATION |
=============================================================
| NodeName | IpAddress | gcware | gcluster | DataState |
-------------------------------------------------------------
| coordinator1 | 10.0.2.102 | OPEN | OPEN | 0 |
-------------------------------------------------------------
| coordinator2 | 10.0.2.202 | OPEN | OPEN | 0 |
-------------------------------------------------------------
| coordinator3 | 10.0.2.203 | OPEN | OPEN | 0 |
-------------------------------------------------------------
=========================================================================================================
| GBASE DATA CLUSTER INFORMATION |
=========================================================================================================
| NodeName | IpAddress | DistributionId | gnode | syncserver | DataState |
---------------------------------------------------------------------------------------------------------
| node1 | 10.0.2.102 | 3 | OPEN | OPEN | 0 |
---------------------------------------------------------------------------------------------------------
| node2 | 10.0.2.202 | 3 | OPEN | OPEN | 0 |
---------------------------------------------------------------------------------------------------------
| node3 | 10.0.2.203 | 3 | OPEN | OPEN | 0 |
-----测试数据
100万行数据
表结构
CREATE TABLE "t2" (
"id" int(11) DEFAULT NULL,
"name" varchar(20) DEFAULT NULL,
KEY "idx_name" ("name") KEY_BLOCK_SIZE=4096 KEY_DC_SIZE=10 USING HASH GLOBAL
)key_dc_size参数
key_dc_size=10, 每个DC是66636行， 10个是65万行。 3个节点接近200万行。预计每次加载100万，大约2-3次会出现一次抖动。
运行效果
和预期相符，一次快，一次慢，很有规律。速度快的24-26秒，慢的30-39秒。
gbase> truncate table t2;
Query OK, 10000041 rows affected (Elapsed: 00:00:00.50)
gbase> load data infile 'ftp://gbase:gbase1234@10.0.2.202//home/gbase/data/ran.txt' into table t2 fields terminated by ',';
Query OK, 1000000 rows affected (Elapsed: 00:00:22.68)
Task 13378 finished, Loaded 1000000 records, Skipped 0 records
gbase> load data infile 'ftp://gbase:gbase1234@10.0.2.202//home/gbase/data/ran.txt' into table t2 fields terminated by ',';
Query OK, 1000000 rows affected (Elapsed: 00:00:25.56)
Task 13379 finished, Loaded 1000000 records, Skipped 0 records
gbase> load data infile 'ftp://gbase:gbase1234@10.0.2.202//home/gbase/data/ran.txt' into table t2 fields terminated by ',';
Query OK, 1000000 rows affected (Elapsed: 00:00:22.09)
Task 13380 finished, Loaded 1000000 records, Skipped 0 records
gbase> load data infile 'ftp://gbase:gbase1234@10.0.2.202//home/gbase/data/ran.txt' into table t2 fields terminated by ',';
Query OK, 1000000 rows affected (Elapsed: 00:00:29.59)
Task 13381 finished, Loaded 1000000 records, Skipped 0 records
gbase> load data infile 'ftp://gbase:gbase1234@10.0.2.202//home/gbase/data/ran.txt' into table t2 fields terminated by ',';
Query OK, 1000000 rows affected (Elapsed: 00:00:22.81)
Task 13382 finished, Loaded 1000000 records, Skipped 0 records
gbase> load data infile 'ftp://gbase:gbase1234@10.0.2.202//home/gbase/data/ran.txt' into table t2 fields terminated by ',';
Query OK, 1000000 rows affected (Elapsed: 00:00:30.04)
Task 13383 finished, Loaded 1000000 records, Skipped 0 records
gbase> load data infile 'ftp://gbase:gbase1234@10.0.2.202//home/gbase/data/ran.txt' into table t2 fields terminated by ',';
Query OK, 1000000 rows affected (Elapsed: 00:00:26.06)
Task 13384 finished, Loaded 1000000 records, Skipped 0 records
gbase> load data infile 'ftp://gbase:gbase1234@10.0.2.202//home/gbase/data/ran.txt' into table t2 fields terminated by ',';
Query OK, 1000000 rows affected (Elapsed: 00:00:34.11)
Task 13385 finished, Loaded 1000000 records, Skipped 0 records
gbase> load data infile 'ftp://gbase:gbase1234@10.0.2.202//home/gbase/data/ran.txt' into table t2 fields terminated by ',';
Query OK, 1000000 rows affected (Elapsed: 00:00:24.57)
Task 13386 finished, Loaded 1000000 records, Skipped 0 records
gbase> load data infile 'ftp://gbase:gbase1234@10.0.2.202//home/gbase/data/ran.txt' into table t2 fields terminated by ',';
Query OK, 1000000 rows affected (Elapsed: 00:00:39.45)
Task 13387 finished, Loaded 1000000 records, Skipped 0 records建议
key_dc_size参数，建议设置为每天或每半天数据量的计算值。简单公式
每天行数/节点数/65536, 然后取整即可。
如果是天表，那就不用了。