diff --git a/src/main/asciidoc/_chapters/datamodel.adoc b/src/main/asciidoc/_chapters/datamodel.adoc index c8164e4696a8..2e6070dbc90b 100644 --- a/src/main/asciidoc/_chapters/datamodel.adoc +++ b/src/main/asciidoc/_chapters/datamodel.adoc @@ -238,6 +238,23 @@ create 'bar', 'fam' ---- ==== +[[namespace_table]] +=== About hbase:namespace table +We used to have a system table called `hbase:namespace` for storing the namespace information. + +It introduced some painful bugs in the past, especially that it may hang the master startup thus +hang the whole cluster. This is because meta table also has a namespace, so it depends on namespace +table. But namespace table also depends on meta table as meta table stores the location of all +regions. This is a cyclic dependency so sometimes namespace and meta table will wait for each other +to online and hang the master start up. + +It is not easy to fix so in 3.0.0, we decided to completely remove the `hbase:namespace` table and +fold its content into the `ns` family in `hbase:meta` table. When upgrading from 2.x to 3.x, the +migration will be done automatically and the `hbase:namespace` table will be disabled after the +migration is done. You are free to leave it there for sometime and finally drop it. + +For more tails, please see https://issues.apache.org/jira/browse/HBASE-21154[HBASE-21154]. + == Table Tables are declared up front at schema definition time. diff --git a/src/main/asciidoc/_chapters/upgrading.adoc b/src/main/asciidoc/_chapters/upgrading.adoc index 83030cc5038a..055acd968078 100644 --- a/src/main/asciidoc/_chapters/upgrading.adoc +++ b/src/main/asciidoc/_chapters/upgrading.adoc @@ -327,6 +327,9 @@ Quitting... The RegionServer Grouping feature has been reimplemented. See section <> in <> for more details. +The `hbase:namespace` table has been removed and fold into `hbase:meta`. See section +<> in <> for more details. + [[upgrade2.4]] There is no special consideration upgrading to hbase-2.4.x from 2.3.x. And for earlier versions, just follow the <> guide. In general, 2.2.x should be rolling upgradeable, for 2.1.x