We should store table metadata in a single location, for HDFS table recovery,
not on every region
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Key: HBASE-2366
URL: https://issues.apache.org/jira/browse/HBASE-2366
Project: Hadoop HBase
Issue Type: Bug
Components: regionserver
Environment: CentOS 5.4, x86_64
Reporter: Cristian Ivascu
Fix For: 0.21.0
Right now, every region has a .regioninfo file that describes what the region
contains. This is used by the add_table tool to recover a table from HDFS, when
there are problems with the .META. table. Right now the .regioninfo file stores
both region-specific as well as table-specific metadata (the columns), which
can cause problems.
One such problem appears when some of the .regioninfo files are not updates.
Workflow to reproduce this is:
1. Create a new table with a list of columns.
2. Push some data into the table, so at least one region exists.
3. Do an ALTER on the table and add some new columns.
3.1 Look at one of the .regioninfo files. They still contain the old list of
columns.
4. Push some more data into the table, containing values for the new columns.
5. Run add_table.rb on this table.
6. Try to push the data at point 4 again. You will get errors -
NoSuchColumnFamilyExists exception.
in our specific case, 10 out of the 140 regions of a table had the initial list
of columns, and the others were updated (as part of splits, as we deduced). We
had to run add_table, which replaced the .META. entries with the ones on disk,
and as a result we couldn't get to our data anymore. Re-writing the .regioninfo
with the correct column list (as done in HRegion.java) and re-adding the table
fixed it for us,.
It should be possible to store the table information in a single location (e.g.
/hbase/table_name/.tableinfo maybe?) and work on it on table create / alter
which would prevent this case from happening again.
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