了解 CockroachDB 副本
Understanding CockroachDB Replicas
我很难理解为什么我的单节点设置中的 CockroachDB 管理控制台有 37 个副本。根据我读到的内容
CockroachDB replicates each range (3 times by default) and stores each replica on a different node.
这直接来自文档 https://www.cockroachlabs.com/docs/v20.2/architecture/overview#glossary
运行命令\l我明白了
database_name
-----------------
defaultdb
postgres
system
test2
(4 rows)
运行命令SHOW ALL ZONE CONFIGURATIONS;我得到
target | raw_config_sql
---------------------------------------------------+------------------------------------------------------------------------------
RANGE default | ALTER RANGE default CONFIGURE ZONE USING
| range_min_bytes = 134217728,
| range_max_bytes = 536870912,
| gc.ttlseconds = 90000,
| num_replicas = 3,
| constraints = '[]',
| lease_preferences = '[]'
DATABASE system | ALTER DATABASE system CONFIGURE ZONE USING
| range_min_bytes = 134217728,
| range_max_bytes = 536870912,
| gc.ttlseconds = 90000,
| num_replicas = 5,
| constraints = '[]',
| lease_preferences = '[]'
RANGE meta | ALTER RANGE meta CONFIGURE ZONE USING
| range_min_bytes = 134217728,
| range_max_bytes = 536870912,
| gc.ttlseconds = 3600,
| num_replicas = 5,
| constraints = '[]',
| lease_preferences = '[]'
RANGE system | ALTER RANGE system CONFIGURE ZONE USING
| range_min_bytes = 134217728,
| range_max_bytes = 536870912,
| gc.ttlseconds = 90000,
| num_replicas = 5,
| constraints = '[]',
| lease_preferences = '[]'
RANGE liveness | ALTER RANGE liveness CONFIGURE ZONE USING
| range_min_bytes = 134217728,
| range_max_bytes = 536870912,
| gc.ttlseconds = 600,
| num_replicas = 5,
| constraints = '[]',
| lease_preferences = '[]'
TABLE system.public.replication_constraint_stats | ALTER TABLE system.public.replication_constraint_stats CONFIGURE ZONE USING
| gc.ttlseconds = 600,
| constraints = '[]',
| lease_preferences = '[]'
TABLE system.public.replication_stats | ALTER TABLE system.public.replication_stats CONFIGURE ZONE USING
| gc.ttlseconds = 600,
| constraints = '[]',
| lease_preferences = '[]'
(7 rows)
我不确定37是从哪里来的，因为我只创建了数据库test2，它不应该只是3吗？或者如果它甚至复制默认数据库，它仍然只有 3*4 = 12？ None 我的数据库超过 512M，因此每个数据库最多只需要 1 个范围。我一定是误会了什么，有人可以帮我吗？谢谢。
Cockroach 内部系统范围比较多。它维护内部系统 tables 以及其他引导元数据。 Cockroach 在 table 边界以及其他一些硬编码分割点上分割范围。您可以通过 运行 查询来发现范围集，例如：
> SELECT start_pretty, end_pretty, database_name, table_name, replicas FROM crdb_internal.ranges_no_leases;
start_pretty | end_pretty | database_name | table_name | replicas
--------------------------------+-------------------------------+---------------+---------------------------------+-----------
/Min | /System/NodeLiveness | | | {1,2,3}
/System/NodeLiveness | /System/NodeLivenessMax | | | {1,2,3}
/System/NodeLivenessMax | /System/tsd | | | {1,2,3}
/System/tsd | /System/"tse" | | | {1,2,3}
/System/"tse" | /Table/SystemConfigSpan/Start | | | {1,2,3}
/Table/SystemConfigSpan/Start | /Table/11 | | | {1,2,3}
/Table/11 | /Table/12 | system | lease | {1,2,3}
/Table/12 | /Table/13 | system | eventlog | {1,2,3}
/Table/13 | /Table/14 | system | rangelog | {1,2,3}
/Table/14 | /Table/15 | system | ui | {1,2,3}
/Table/15 | /Table/16 | system | jobs | {1,2,3}
/Table/16 | /Table/17 | | | {1,2,3}
/Table/17 | /Table/18 | | | {1,2,3}
/Table/18 | /Table/19 | | | {1}
/Table/19 | /Table/20 | system | web_sessions | {1,2,3}
/Table/20 | /Table/21 | system | table_statistics | {1,2,3}
/Table/21 | /Table/22 | system | locations | {1,2,3}
/Table/22 | /Table/23 | | | {1,2,3}
/Table/23 | /Table/24 | system | role_members | {1,2,3}
/Table/24 | /Table/25 | system | comments | {1,2,3}
/Table/25 | /Table/26 | system | replication_constraint_stats | {1,2,3}
/Table/26 | /Table/27 | system | replication_critical_localities | {1,2,3}
/Table/27 | /Table/28 | system | replication_stats | {1,2,3}
/Table/28 | /Table/29 | system | reports_meta | {1}
/Table/29 | /NamespaceTable/30 | | | {1,2,3}
/NamespaceTable/30 | /NamespaceTable/Max | system | namespace2 | {1,2,3}
/NamespaceTable/Max | /Table/32 | system | protected_ts_meta | {1,2,3}
/Table/32 | /Table/33 | system | protected_ts_records | {1,2,3}
/Table/33 | /Table/34 | system | role_options | {1,2,3}
/Table/34 | /Table/35 | system | statement_bundle_chunks | {1,2,3}
/Table/35 | /Table/36 | system | statement_diagnostics_requests | {1,2,3}
/Table/36 | /Table/37 | system | statement_diagnostics | {1}
/Table/37 | /Table/38 | system | scheduled_jobs | {1,2,3}
/Table/38 | /Table/39 | | | {1,2,3}
/Table/39 | /Max | system | sqlliveness | {1,2,3}
(35 rows)
replicas 字段中的每个条目代表一个副本。希望这能让您深入了解存在的范围。
我很难理解为什么我的单节点设置中的 CockroachDB 管理控制台有 37 个副本。根据我读到的内容
CockroachDB replicates each range (3 times by default) and stores each replica on a different node.
这直接来自文档 https://www.cockroachlabs.com/docs/v20.2/architecture/overview#glossary
运行命令\l我明白了
database_name
-----------------
defaultdb
postgres
system
test2
(4 rows)
运行命令SHOW ALL ZONE CONFIGURATIONS;我得到
target | raw_config_sql
---------------------------------------------------+------------------------------------------------------------------------------
RANGE default | ALTER RANGE default CONFIGURE ZONE USING
| range_min_bytes = 134217728,
| range_max_bytes = 536870912,
| gc.ttlseconds = 90000,
| num_replicas = 3,
| constraints = '[]',
| lease_preferences = '[]'
DATABASE system | ALTER DATABASE system CONFIGURE ZONE USING
| range_min_bytes = 134217728,
| range_max_bytes = 536870912,
| gc.ttlseconds = 90000,
| num_replicas = 5,
| constraints = '[]',
| lease_preferences = '[]'
RANGE meta | ALTER RANGE meta CONFIGURE ZONE USING
| range_min_bytes = 134217728,
| range_max_bytes = 536870912,
| gc.ttlseconds = 3600,
| num_replicas = 5,
| constraints = '[]',
| lease_preferences = '[]'
RANGE system | ALTER RANGE system CONFIGURE ZONE USING
| range_min_bytes = 134217728,
| range_max_bytes = 536870912,
| gc.ttlseconds = 90000,
| num_replicas = 5,
| constraints = '[]',
| lease_preferences = '[]'
RANGE liveness | ALTER RANGE liveness CONFIGURE ZONE USING
| range_min_bytes = 134217728,
| range_max_bytes = 536870912,
| gc.ttlseconds = 600,
| num_replicas = 5,
| constraints = '[]',
| lease_preferences = '[]'
TABLE system.public.replication_constraint_stats | ALTER TABLE system.public.replication_constraint_stats CONFIGURE ZONE USING
| gc.ttlseconds = 600,
| constraints = '[]',
| lease_preferences = '[]'
TABLE system.public.replication_stats | ALTER TABLE system.public.replication_stats CONFIGURE ZONE USING
| gc.ttlseconds = 600,
| constraints = '[]',
| lease_preferences = '[]'
(7 rows)
我不确定37是从哪里来的，因为我只创建了数据库test2，它不应该只是3吗？或者如果它甚至复制默认数据库，它仍然只有 3*4 = 12？ None 我的数据库超过 512M，因此每个数据库最多只需要 1 个范围。我一定是误会了什么，有人可以帮我吗？谢谢。
Cockroach 内部系统范围比较多。它维护内部系统 tables 以及其他引导元数据。 Cockroach 在 table 边界以及其他一些硬编码分割点上分割范围。您可以通过 运行 查询来发现范围集，例如：
> SELECT start_pretty, end_pretty, database_name, table_name, replicas FROM crdb_internal.ranges_no_leases;
start_pretty | end_pretty | database_name | table_name | replicas
--------------------------------+-------------------------------+---------------+---------------------------------+-----------
/Min | /System/NodeLiveness | | | {1,2,3}
/System/NodeLiveness | /System/NodeLivenessMax | | | {1,2,3}
/System/NodeLivenessMax | /System/tsd | | | {1,2,3}
/System/tsd | /System/"tse" | | | {1,2,3}
/System/"tse" | /Table/SystemConfigSpan/Start | | | {1,2,3}
/Table/SystemConfigSpan/Start | /Table/11 | | | {1,2,3}
/Table/11 | /Table/12 | system | lease | {1,2,3}
/Table/12 | /Table/13 | system | eventlog | {1,2,3}
/Table/13 | /Table/14 | system | rangelog | {1,2,3}
/Table/14 | /Table/15 | system | ui | {1,2,3}
/Table/15 | /Table/16 | system | jobs | {1,2,3}
/Table/16 | /Table/17 | | | {1,2,3}
/Table/17 | /Table/18 | | | {1,2,3}
/Table/18 | /Table/19 | | | {1}
/Table/19 | /Table/20 | system | web_sessions | {1,2,3}
/Table/20 | /Table/21 | system | table_statistics | {1,2,3}
/Table/21 | /Table/22 | system | locations | {1,2,3}
/Table/22 | /Table/23 | | | {1,2,3}
/Table/23 | /Table/24 | system | role_members | {1,2,3}
/Table/24 | /Table/25 | system | comments | {1,2,3}
/Table/25 | /Table/26 | system | replication_constraint_stats | {1,2,3}
/Table/26 | /Table/27 | system | replication_critical_localities | {1,2,3}
/Table/27 | /Table/28 | system | replication_stats | {1,2,3}
/Table/28 | /Table/29 | system | reports_meta | {1}
/Table/29 | /NamespaceTable/30 | | | {1,2,3}
/NamespaceTable/30 | /NamespaceTable/Max | system | namespace2 | {1,2,3}
/NamespaceTable/Max | /Table/32 | system | protected_ts_meta | {1,2,3}
/Table/32 | /Table/33 | system | protected_ts_records | {1,2,3}
/Table/33 | /Table/34 | system | role_options | {1,2,3}
/Table/34 | /Table/35 | system | statement_bundle_chunks | {1,2,3}
/Table/35 | /Table/36 | system | statement_diagnostics_requests | {1,2,3}
/Table/36 | /Table/37 | system | statement_diagnostics | {1}
/Table/37 | /Table/38 | system | scheduled_jobs | {1,2,3}
/Table/38 | /Table/39 | | | {1,2,3}
/Table/39 | /Max | system | sqlliveness | {1,2,3}
(35 rows)
replicas 字段中的每个条目代表一个副本。希望这能让您深入了解存在的范围。