12c Database: New Features List 2

Few more collection of new features with in 12c database in continuation to my earlier post in this category

RMAN Enhancements:-

• Recover or copy files from Standby databases
• Table level restoration i.e object level
• Incremental recovery more faster, many of the tasks removed

RAC Enhancements:-

• TAF is extended to Transactions failover (insert/update/delete)

Dataguard Enhancements:-

• Global data services, transparent to failover / switchover no client reconfiguration required

Grid Infrastructure Enhancements:-

• Introduction of Flex Cluster , with light weight cluster stack, leaf node and traditional stack hub node, application layer is the typical example of leaf nodes where they dont require any network heartbeat
• Introduction of Flex ASM, ASM would run only on 3 instances on a cluster even if more than 3, the instances that not have an ASM would request remote ASM, typically like SCAN. In normal conditions in a node if ASM fails the entire node will be useless, where in 12c the ability to get the extent map from remote ASM instance makes the node useful.

DBConsole, introduction to EM Express:-

• End of DBConsole, introduction to EM Express interface similar like cloud
• Smaller disk usage less than 50MB compare to DBConsole
• Real Time ADDM, runs every 3 sec, collects all information and provide GUI interface as like Cloud
• Integrated and preconfigured
• Database performance hub, which shows all graphs similar like Cloud/DBConsole

ILM:-

• In database archive, Seperation of archived data with in the database, Marks rows invisible as archived
• Data optimization, Move data based on policies (move,compres,read only etc)
• Heat maps, how recently the data is accessed, Table level, row level, Partition level heat maps
• In memory scan without expanding/extracting the compressed data which allows the retrieval of data more faster

Performance Enhancements:-

• Adaptive statistics collection

Actual number of rows <> estimates
– Statistics marked as ‘incorrect’ / ‘unreliable’
– Next query will do ‘dynamic sampling’
• Results in much better estimates
• Better execution plans

• – E.g. 2 options in execution plan
  • Join using nested loops
     – Best when few rows need to be joined
  • Join using hash join
     – Best when a lot of rows need to be joined
     – “Inflection point”
  • Rows are buffered during execution of query
  • Inflection point reached or not?: take plan 1 or 2
  – Result: “deferred execution plan”

-Thanks

Geek DBA