IN-MEMORY population/[trickle] re-population : How much work ? Part 2

In one of my previous blog post i demonstrated that the amount of work needed for IN-MEMORY population/[trickle] re-population in oracle 12.1.0.2.6 is more than we may expect : IN-MEMORY population/[trickle] re-population : How much work ? You may be surprised !

Let’s do a very quick check  on how this is now handled in oracle 12.2.0.1/OEL 6/UEK4

As in my previous post i will trace the work done by the In-memory  background worker processes W0nn during population and  trickle re-population using a systemtap script. trace_oracle_logical_io_basic.stp

NOTE : If you receive “inode-offset registration error (rc 0)”  using systemtap then check   this post :  Workaround for systemtap issue : Oracle Tracing [registration error (rc 0) !]

Test of In-memory population :

Create a table and load it IN-MEMORY.

capture 01

Let’s check the systemtap trace file :

Capture 02

It’s seem that for some reason the IN-MEMORY population still need to reread the segment multiple times !

Test of In-memory re-population :

So here we gonna update a row which is located at block number “24491”.

capture 05

Let’s check the systemtap trace file

Capture 06

There is huge improvement here compared with the previous release ! Only the needed block “21491” is reread (block 21472 is the segment header)

That’s it 😀

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