The theme of this edition is "DB2 recovery". Check out the link below to find more http://content.emm.ibmmail.com/frontend/dynamicAssets?e=t1265FF49FBF9450CDC8CB7BEFD638B2B44F8F925ECFB432943722976C87A34845591957300630E4900A467C15C2F9679F410CBA0C3A26F9522DCF20CA7FFC1344ADEA7E888AF3EF5DA087CC57C7087C5F4C13C563393ACD51AEFBFF9B0229DB3502FDA80BA565411

Tags:  db2， recovery newsletter

We are sometimes asked questions about plan stability. For example. -We can correct stats and check the access plan, but if we no longer correct stats, will the plan be stable ? -Does applying db2look -m output generates the same plan on another databases ?     The answers are no, not always. Even after collecting stats, DB2 may fabricate stats which may change the access plan if the data fits into initially allocated one page of the table and exceeded later on. Here's the outlined repro scenario of the symptom. Note, It can be... [More]

Tags:  db2luw optimizer

  We have a very good knowledge center document to follow when upgrading db2 servers in MSCS set-ups :       Upgrading DB2 servers in Microsoft Cluster Server environments                                                 ... [More]

Tags:  db2support db2luw

Being able to track the list and frequency of dynamic libraries or objects being loaded and unloaded might be handy sometimes.   Loading a library is somewhat 'time consuming' because the dynamic loader will have, at one point or another, to resolve symbols used in the newly loaded object. Also care must be taken when unloading a library that nothing else still references that library. Failure to do so would most often lead to a crash with SIGSEGV or SIGILL.   It is not uncommon for database engines or other applications to... [More]

Tags:  dynamic_library probevue

Recently we saw a problem where customer was having a delay in connection to the database through SAP (R3trans).   Sharing the list of steps we took to isolate(narrow down) the problem area, find the root cause and fix it. In a setup involving many products and locations, trying to isolate the area of the problem is the best approach to avoid spending time in checking unrelated components.   Some primary checks to help isolate this case : Got following information : 1> Problem was originally seen with the connection from the... [More]

Tags:  db2support db2luw

In HADR environment, after takeover on Standby, you may find some tablespaces in rollforward pending state. However, if you attempt to do rollforward on these tablespaces, SQL1744N may be returned. For example, $ db2 rollforward db sample to end of logs tablespace '(ts1)' online SQL1774N  Table space restore or rollforward cannot be issued on an HADR primary or HADR standby database. $ db2 rollforward db sample to end of logs SQL1774N  Table space restore or rollforward cannot be issued on an HADR primary or HADR standby... [More]

This small probevue script will let you know who killed your process. Sometimes you might see that a process gets killed for no obvious reason and you have no idea who killed it. Of course here we're not talking about process dying because of a SEGV or SIGBUS, due to programming errors, but a genuine kill.   In the script below you can of course alter the SIGKILL in the '/ ... /' filter by another signal. The script has to be run as root like this:     # /usr/sbin/dtrace -w -q -o sigkill1.out -s sigkill1.dt   The... [More]

Tags:  dtrace kill

Last month, a client told me that on his product server, importing into a table with schema specified took about 700 seconds, while importing into the same table without schema, it only took 100 seconds: db2 "import from date.ixf of ixf commitcount 10000 insert into tbl_cufms_cuslt_settle_rslt_mchnt"                    # this command took about 100 seconds   db2 "import from date.ixf of ixf commitcount 10000 insert into... [More]

Tags:  db2;import;performance

When using DELETE queries,  especially searched deletes which may delete many rows at a time,  there are index considerations which can be important to getting good performance,  if there are foreign key constraints present.  These are helpful to be aware of in advance,  since the absence of the right indexes may result in suboptimal delete performance,  and the cause may not be immediately evident from looking at the plan graph in a explain (db2exfmt output).     A typical scenario of this kind might... [More]

Tags:  db2 query key index delete foreign performance

There may be occasions that you want to change the tablespaces from the current pagesize to a different one, for instance from 4KB to 8KB. Please note tablespaces pagesize cannot be changed directly. However, you can use the following steps to move the tables to the new tablespaces with the pagesize you want and then drop the original tablespaces once you confirm the new tablespaces work(the following is an example to move to 8KB tablespaces): 1.Create a bufferpool with 8KB pagesize if you don't have one already db2 CREATE BUFFERPOOL... [More]

File locking is an essential concept for insuring data integrity. It is quite common for programs to 'lock' files to make sure that what they read is accurate or to prevent anyone from reading or writing the file that they are modifying.   Because of that it might happen that your program fails to acquire a lock on a file. While some programs will handle this silently by retrying to obtain the lock some might report an error, hang waiting to acquire the lock or simply terminate.   Most users know about the 'fuser'... [More]

Tags:  lock chklock fcntl

I have configured TSA+HDAR environment by db2haicu. To check if HADR is working I can use "db2pd -db <DBname> -hadr" command, but how can I check if TSAMP is working with no problem?   The most straightforward method is through "lssam" command. Here is an example of "lssam" output of a TSAMP managed HADR: [root@clnode1 ~]# lssam Online IBM.ResourceGroup:db2_db2inst1_clnode1_0-rg Nominal=Online         '- Online IBM.Application:db2_db2inst1_clnode1_0-rs... [More]

This small article tries to answer the following question that came via support channel:     "What does it mean really when send() fails with EAGAIN/EWOULDBLOCK?"   So... without going to much into details let's try to answer this. First let's walk over a few definitions, once again trying to keep a simple vocabulary here.   - socket - A socket is special file used in network transports. In a very simple way you could see a socket as a 'pipe' that can be used to send data over the network. So it has... [More]

Tags:  ewouldblock socket eagain

Occasionally, there are times when you need to define or change the starting point of replication for tools like IBM  Infosphere Data Replication or other 3rd party tools that use the Asynchronous Log Reader (ALR) code to parse the DB2 transaction logs.  That usually requires have the starting LSN (Log Sequence Number) or LRI (Log Record Identifier) value.  The LRI value is composed of the LFS (Log File Sequence) and the LSN values. There is a tool (db2logsForRfwd) in DB2 that uses the tablespace change history file... [More]

Tags:  db2 replication