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]
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]
RUNSTATS has an option UTIL_IMPACT_PRIORITY which as its name suggests, specifies the priority of RUNSTATS utility. However, be aware of the following implications Option Specified RUNSTATS Priority Option UTIL_IMPACT_PRIORITY not specified Unthrottled Option UTIL_IMPACT_PRIORITY used, no value specified Throttled, Priority is 50 (Default) Option UTIL_IMPACT_PRIORITY used, value 1 to 100 specified Throttled, Priority is 1 to 100 as specified : When RUNSTATS is throttled, the overall performance impact is controlled by... [More]
db2_install / installfixpack fails with "DBI1058E gunzip command not found" error. # ./db2_install -b /opt/tivoli/tsm/db2 DBI1324W Support of the db2_install command is deprecated. DBI1058E gunzip command not... [More]
Why "db2prereqcheck -l" does not return any output? -l option checks the prerequisites related to pureScale and unrelated to DB2 pureScale environments for the latest DB2 version that is defined in the XML resource file.
If -l option is specified, there won't be any screen output if all prerequisites are met - this is expected behavior. Otherwise, a summary list of error will be shown on screen and in report file. For example: Summary of prerequisites not meeting minimum requirement... [More]
When federated query performance is slow due to the slow response time of query processing in remote data source side, you may want to tune the query processing in DB2 remote data source side. Let's assume following situation. - You have encountered a slow query in a SQL procedure in federation database. - A part of the slow query shipped to remote DRDA data source by federation was actually slow. Note, SQL compiler decides the query text to ship to remote data source. The query text being shipped can be found in RMTQTXT argument in... [More]
Enabling Workload Balancing (WLB) for a DB2 pureScale instance is very easy. There are two methods of WLB available for use: connection-level balancing and transaction-level balancing. The WLB feature is automatically on at the DB2 member server. The client configuration is where WLB features are enabled. With a quick modification of the db2dsdriver.cfg file or the java connection properties the WLB features can be exploited so that as members are added to the instance performance can almost scale linearly. To find out if your... [More]
The art of being a DBA includes being able to tune the database to the needs of the client applications accessing it. One of the many avenues of this art is the ability to tune the logging parameters such they are not constraining performance. The log file size along with the number of primary and secondary logs in the DB2 configuration are the principle means to accomplish this. The ideal number of logs a DB2 database requires starts with good understanding of the clients using the it. There... [More]
We will provide non-defect support for business continuity(including access to existing fixes) for DB2 v9.7 and v10.1 beyond their End of Service(EOS) date(Sep.2017). This exciting offering allows you to enjoy many of the S&S benefits . It is : Enhancement to existing Subscription & Support Extends time allowed for client upgrades How-To and workaround assistance Provides pre-existing fixes It is not : Replacement for Subscription & Support Replacement for Service Extension. Defect fixes. Support for custom special builds or code... [More]
Data Science Experience is an extremely powerful and flexible platform for exploring a wide variety of tools and capabilities related to data science. For example, DSX brings together all the assets you need (including working code, sample data sets, and in-depth tutorials) to explore the power of machine learning. With the introduction of DSX Local , you now have many possible combinations of platform and data source to explore, including: All public cloud: DSX Public Cloud with data source in public cloud (e.g. dashDB) Private... [More]
Question: Why does "prune history and delete" retain history entries and LOG files on V10.5 FP8? Cause: It is an known expected behavior. Answer: Here is a sample test scenario. ---------- #!/bin/ksh db2 drop db db1 export ARCHMETH=/tmp/archmeth rm -rf $ARCHMETH mkdir $ARCHMETH db2 create db db1 db2 connect to db1 db2 "create table t1(c1 int)" db2 update db cfg for db1 using LOGFILSIZ 10 LOGPRIMARY 6 LOGSECOND 2 db2 update db cfg for db1 using LOGARCHMETH1 DISK:$ARCHMETH db2 backup db db1 to /dev/null db2 connect to... [More]
DB2 v9.7 and v10.1 will be EOS(end of support) on Sep. 30, 2017. Customers can upgrade their DB2 v9.7 or v10.1 systems to DB2 v11.1 FP1 directly to skip 11.1 GA version. The first fix pack delivered for DB2 V11.1 changes the modification level of the product to 1 and has the product signature of DB2 126.96.36.199. Subsequent fix packs for the DB2 V11.1 product will be based on this modification level (e.g. the next fix pack will have the signature DB2 188.8.131.52).