Dec-14

30-Dec

 

Index Full Scan:

  • Returns Data in sorted order
  • Scan will not use multiblock reads
  • At least one column in the index is not NULL

Index Fast Full Scan

  • Use multiblock reads
  • Use parallelism
  • Rows returned NOT sorted order
  • Use only if all required columns are in the index
  • Do not return ROWIDs for subsequent table access

05-Dec

Parallel_force_local =  TRUE – parameter restricts the PX servers local to the parent process node and not distributed across the RAC nodes

Oracle 12c – password file can be created in ASM as follows.  Make sure the selected FORMAT is 12

orapwd  file=’+DATA/orcl/orapworcl’ ENTRIES=10 FORMAT=12 DBUNIQUENAME=’ORCL’

Linux Parameter – swappiness  holds value between 0 – 100 which will decide the aggressiveness swapping the physical memory when the pages are idle and the default value is 60.   For database servers it is not recommend to keep the default value 60 as it can aggressively flush physical memory pages to the VM.  The Red hat recommended value is 10.

You may set the parameter vm.swappiness=10 in /etc/sysctl.conf to set the values permanently.  Or to set the value temporary set as follows

$ echo 10 > /proc/sys/vm/swappiness

PGA_AGGREGATE_LIMT : PGA memory is defined by pga_aggregate_target in database level and is not a har5d limit.  Oracle 12c introduces a new parameter pga_aggregate_limit which will restrict the growth of the PGA.  By default it will be maximum of 2GB or 200% of the pga_aggregate_target.  In databases with large PGA target configurations, it is necessary to set the PGA limit rather leaving to the default value of 200% of PGA target.

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