DB2 FOR LUW / DB2FORLUW / B50 - DB2

Auto REORG..RECOMPRESS and online backup cannot be run
concurrently.
Thus, if online backup is running, auto REORG..RECOMPRESS will
be interrupted.
However, there is currently an issue if auto REORG..RECOMPRESS
is interrupted by online backup, most commonly found in the case
where online backup is already running and auto
REORG..RECOMPRESS is attempted on the table.
If this occurs, it is possible that auto REORG..RECOMPRESS will
not run again on this table, even if it still has data that
requires recompression.
Additionally, this prevents reclaim from releasing pages that
were deleted by processes such as logical truncate.
These problems will persist until the database is restarted.
This can cause frequently truncated tables to grow in size
because their deleted pages are not reclaimed.

db2level:
Informational tokens are "DB2 v11.5.4.0"

example issue:
----
A sign that this issue may be occurring can be if RECLAIMABLE
SPACE is 0 after LOGICAL TRUNCATE and RUNSTATS on a table:
SELECT SUM(RECLAIMABLE_SPACE) as RECLAIMABLE_SPACE FROM
TABLE(SYSPROC.ADMIN_GET_TAB_INFO('SCHEMA', 'TABLENAME'))

        RECLAIMABLE_SPACE
        --------------------
                       0

          1 record(s) selected.
Additional signs that this issue may be happening is if messages
similar to the following are found in the db2diag.log for the
same table:
============
2021-03-18-15.57.02.504505-420 I200238E752           LEVEL: Info
PID     : 30481                TID : 139990201788160 PROC :
db2sysc
INSTANCE: xxxx             NODE : 000            DB   : USID
APPHDL  : 0-73                 APPID: *LOCAL.DB2.210318225654
AUTHID  : aaaa             HOSTNAME: db2i-xxxx-ss9r6-x86
EDUID   : 217                  EDUNAME: db2taskp (USID)
FUNCTION: DB2 UDB, CDE Data, TableAction::recompress, probe:2009
MESSAGE : ZRC=0x870F0035=-2029060043=SQLO_NOTAVAIL
          "Cannot honor the conditional request"
          DIA8531C A memory access error has occurred.
DATA #1 : String, 122 bytes
REORG TABLE "SCHEMA.TABLENAME" RECOMPRESS did not get OLB latch.
OLB is in progress. Daemon will relaunch recompress.

2021-03-18-15.57.04.877573-420 I201664E668           LEVEL:
Event
PID     : 30481                TID : 140011164919552 PROC :
db2sysc
INSTANCE: xxxx             NODE : 000            DB   : USID
APPHDL  : 0-38                 APPID: *LOCAL.xxxx.210318225313
UOWID   : 4                    ACTID: 1
AUTHID  : aaaa             HOSTNAME: db2i-xxxx-ss9r6-x86
EDUID   : 146                  EDUNAME: db2agent (USID)
FUNCTION: DB2 UDB, CDE Data,
TableTruncater::TruncateData::getOLBLock, probe:100
DATA #1 : String, 53 bytes
Backup is running. Downgrading to logical truncation.
DATA #2 : Table name with schema, 21 bytes
SCHEMA.TABLENAME
=============

****************************************************************
* USERS AFFECTED:                                              *
* all                                                          *
****************************************************************
* PROBLEM DESCRIPTION:                                         *
* See Error Description                                        *
****************************************************************
* RECOMMENDATION:                                              *
* Upgrade to 11.5.6                                            *
****************************************************************

A workaround to reclaim the space from any frequently truncated
tables that are exhibiting increases in size
would be to run "TRUNCATE TABLE DROP STORAGE IMMEDIATE"
when online backup is not running to release those pages back
into the tablespace.

A sign that this issue may be occurring can be if RECLAIMABLE
SPACE is 0 after LOGICAL TRUNCATE and RUNSTATS on a table.
Also fixed permanently in DB2 v11.5.6

****************************************************************
* USERS AFFECTED:                                              *
* all                                                          *
****************************************************************
* PROBLEM DESCRIPTION:                                         *
* See Error Description                                        *
****************************************************************
* RECOMMENDATION:                                              *
* Upgrade to 11.5.6                                            *
****************************************************************

Upgrade to 11.5.6

Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :

23.03.2021
10.06.2021
10.06.2021