数据部分何时合并
When Data part will be merge
我正在使用 CollapsingMergeTree 引擎按照文档更新数据 (https://clickhouse.yandex/docs/en/operations/table_engines/collapsingmergetree/#collapsing)
基于文档：
CollapsingMergeTree asynchronously deletes (collapses) pairs of rows if all of the fields in a row are equivalent excepting the particular field Sign which can have 1 and -1 values
和
As we need only the last state of user activity, the rows [....]
can be deleted collapsing the invalid (old) state of an object. CollapsingMergeTree does this while merging of the data parts.
我能知道什么时候合并数据部分吗？是否有命令强制 Clickhouse 合并数据部分？
谢谢。
Can I know when Data parts will be merge ?
ClickHouse 以不确定的方式安排异步作业。参见 https://github.com/yandex/ClickHouse/blob/master/dbms/src/Storages/MergeTree/BackgroundProcessingPool.cpp#L29
这些工作包括 data parts clean up、data parts merge 和 data parts mutation。
And is there command to force Clickhouse to merge data part ?
是的，https://clickhouse.yandex/docs/en/query_language/misc/#optimize
我正在使用 CollapsingMergeTree 引擎按照文档更新数据 (https://clickhouse.yandex/docs/en/operations/table_engines/collapsingmergetree/#collapsing)
基于文档：
CollapsingMergeTree asynchronously deletes (collapses) pairs of rows if all of the fields in a row are equivalent excepting the particular field Sign which can have 1 and -1 values
和
As we need only the last state of user activity, the rows [....] can be deleted collapsing the invalid (old) state of an object. CollapsingMergeTree does this while merging of the data parts.
我能知道什么时候合并数据部分吗？是否有命令强制 Clickhouse 合并数据部分？
谢谢。
Can I know when Data parts will be merge ?
ClickHouse 以不确定的方式安排异步作业。参见 https://github.com/yandex/ClickHouse/blob/master/dbms/src/Storages/MergeTree/BackgroundProcessingPool.cpp#L29
这些工作包括 data parts clean up、data parts merge 和 data parts mutation。
And is there command to force Clickhouse to merge data part ?
是的，https://clickhouse.yandex/docs/en/query_language/misc/#optimize