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From Omri Cohen <Omri_co...@outlook.com>
Subject Re: Mob reference tags go missing
Date Sat, 17 Aug 2019 13:42:32 GMT
Sorry, accidentally pressed "send" before i finished the massage.

Hello,

We recently encountered a problem in our production hbase cluster (CDH deployment, version
5.13.1).

We have a cluster with a high mob percentage ( > 50% of objects are MOB, the threshold
is the default 102400 bytes). The cluster has been active for about a year. Recently, our
clients started to receive the mob reference instead of the mob data when trying to access
certain rows (in most tables about 10% of the rows are bad, in one table it is about 50% of
rows).

When we investigated the HFiles, we saw that the "bad" cells are missing two tags that exist
in the "good" rows, it looks something like that:

K: {rowkey of a "good" row} {Column family, column qualifier}... vlen=76/seqid=... V: \x00\x04\xFB.{MOB
file name} T[0]:  T[1]: {table name}
K: {rowkey of a "bad" row} {Column family, column qualifier}... vlen=76/seqid=... V: \x00\x13\x1A{MOB
file name}

The "good" row returns the expected data when queried, while the "bad" row returned the mob
file reference instead of the data. This happened when we queried from the REST server, the
native java client, and the hbase shell.

When we examined the mob files, we saw that all the data was there.

  *   Has anyone encountered a similar situation?
  *   Is it possible to manually add the missing mob reference tags to the "bad" rows?

No changes where made to the table in recently. We never encountered this issue before.

We would appreciate any help on this issue.
________________________________
From: Omri Cohen
Sent: Saturday, August 17, 2019 4:28 PM
To: hbase-user@hadoop.apache.org <hbase-user@hadoop.apache.org>
Subject: Mob reference tags go missing

Hello,

We recently encountered a problem in our production hbase cluster.
We have a cluster with a high mob percentage ( > 50% of objects are MOB, the threshold
is the default 102400 bytes). The cluster has been active for about a year. Recently, our
clients started to receive the mob reference instead of the mob data when trying to access
certain rows (in most tables about 10% of the rows are bad, in one table it is about 50% of
rows).

When we investigated the HFiles, we saw that the "bad" cells are missing two tags that exist
in the "good" rows, it looks something like that:

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