News from Db2 Development and Support: New Fix Packs, Recommendations for Intrapartition Parallelism
New Modification Packs Released by SAP
SAP has certified the following fix packs and modification packs for IBM Db2:
- IBM Db2 11.1 MP2 FP2SAP
- IBM Db2 10.5 FP8SAP3
- IBM Db2 10.1 FP6SAP
- IBM Db2 9.7 FP11SAP
If you are closely watching IBM’s security bulletins, you might be glad to hear that these SAP-certified Fix Packs contain the following APARs:
- Security Bulletin: IBM® DB2® LUW on AIX and Linux Affected by vulnerabilities in zlib (CVE-2016-9840, CVE-2016-9841)
- Security Bulletin: IBM® DB2® LUW’s Command Line Processor Contains Buffer Overflow Vulnerability (CVE-2017-1297)
- Security Bulletin: Buffer overflow vulnerability in IBM® DB2® LUW (CVE-2017-1105)
- APAR IT21242: SQL0901N when SAPTOOLS.MEMORY_TABLE joins with UNION DISTINCT having JOIN (10.5 only)
For more details about fix packs certified by SAP, read our SAP Note 101809.
New Recommendations for Intrapartition Parallelism
We have updated our recommendations for intrapartition parallelism.
Intrapartition parallelism allows you to make better use of large multi-core machines because it allows expensive statements to be executed with parallelism. We’ve already recommended intrapartition parallelism to customers for quite some time, but we decided to update the settings. You influence intrapartition parallelism with a few parameter and registry settings, among them INTRA_PARALLEL, DB2_RESOURCE_POLICY, DFT_DEGREE, and MAX_QUERYDEGREE.
Here is a short summary of the changes – but make sure you read SAP Note 2047006 for all the details:
We now recommend that you set DB2_RESOURCE_POLICY to AUTOMATIC if all of the following conditions apply:
- You use BLU Acceleration.
- Your database server has more than one socket.
- Your database server runs on AIX or Linux x86_64.
- You do not use DPF.
MAX_QUERYDEGREE should be set to a fixed value, depending on your database server hardware.
In the past, we allowed a value less than 48, but now we recommend much lower values:
<= 24 (for systems with BLU Acceleration)
<= 16 (for systems without BLU Acceleration)
Note that 24 and 16 are the maximum values, so don’t set them blindly: first have a closer look at our recommendations how to find an optimal value for MAX_QUERYDEGREE in SAP Note 2047006.
For SAP NetWeaver 7.5, in the past, we required that you set INTRA_PARALLEL to YES and DFT_DEGREE=ANY. That hasn’t changed. However, the requirement is now a bit more relaxed: If you prefer not to enable intrapartition parallelism for the entire system, you can also set DFT_DEGREE=1.
For a complete overview of all recommended settings for intrapartition parallelism, see SAP Note 2047006.