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Exadata

What’s new with Oracle database 19.7 versus 19.6

This blogpost takes a look at the technical differences between Oracle database 19 PSU 6 (january 2020) and 7 (april 2020). This gives technical specialists an idea of the differences, and gives them the ability to assess if the PSU impacts anything.

Functions

What’s new with Oracle database 18.9 versus 18.10

This blogpost takes a look at the technical differences between Oracle database 18 PSU 9 (january 2020) and 10 (april 2020). This gives technical specialists an idea of the differences, and gives them the ability to assess if the PSU impacts anything.

Functions

What’s new with Oracle database 12.1.0.2.200114 versus 12.1.0.2.200414

This blogpost takes a look at the technical differences between Oracle database 12.1.0.2 PSU 200114 (january 2020) and 200414 (april 2020). This gives technical specialists an idea of the differences, and gives them the ability to assess if the PSU impacts anything.

Parameters
The list of parameters removed (first) and parameters added (second) is remarkable long.
It’s striking that a lot of solutions for bugs made configurable (_bug[0-9]*_.*) have been removed, and probably returned back as ‘spare parameters’.
Also some in memory (_inmemory.*) parameters have been removed.
Also some documented parameters; exafusion_enabled and optimizer_adaptive_plans and optimizer_adaptive_statistics, plus some standby parameters I wasn’t aware of existing.

What’s new with Oracle database 11.2.0.4.200114 versus 11.2.0.4.200414

This blogpost takes a look at the technical differences between Oracle database 11.2.0.4 PSU 200114 (january 2020) and 200414 (april 2020). This gives technical specialists an idea of the differences, and gives them the ability to assess if the PSU impacts anything.

Functions

Oracle library cache cursor child generation

This post is about library cache SQL cursors, and how these are managed by the database instance.

Oracle multi-tenant and library cache isolation

This post is the result of a question that I got after presenting a session about Oracle database mutexes organised by ITOUG, as a response to the conference cancellations because of COVID-19. Thank Gianni Ceresa for asking me!

The library cache provides shared cursors and execution plans. Because they are shared, sessions can take advantage of the work of previous sessions of creating these. However, by having these shared, access needs to be regulated not to have sessions overwrite each other’s work. This is done by mutexes.

The question I got was (this is a paraphrased from my memory): ‘when using pluggable databases, could a session in one pluggable database influence performance of a session in another pluggable database’?

Oracle rowcache fastgets

This blogpost is about the Oracle database row or dictionary cache. This is a separate cache that caches database metadata, like database object properties or user properties.

There is surprising little in-depth technical detail about the row cache. To some degree I understand: issues with the row cache are rare.

I noticed a column in V$ROWCACHE called ‘FASTGETS’. Whatever FASTGETS means, in my database it is being used:

Exadata Workloads to Azure, Part II

In my last post, I discussed some of the unique challenges migrating Oracle workloads from Exadata to Azure posed.  Engineered systems are not your everyday lift and shift and are rarely simple.

Although I covered some focus areas for success, I’d like to get into the migration philosophical questions around cell offloading and IO.  cell information is referred to in the average Oracle 12c AWR report almost 350 times.  That’s a LOT of data to consider when migrating a workload to a server that won’t have cell nodes to OFFLOAD TO.

If cell nodes are creating a ton of different IO in Exadata and don’t exist in Azure, will it require IO in Azure?

Migrating Oracle Exadata Workloads to Azure

I know, I know-  there’s a number of you out there thinking-

I’m being brought in on more and more of these projects due to a recent change for some Exadata backup components many companies kept onsite, (parts that wear out more often, like PDUs and cell disks) which are no longer an option and that moving to Azure is a viable option for these workloads if you know what to identify and address before the move to the cloud.

What’s new with Oracle database 12.2.0.1.191015 versus 12.2.0.1.200114

For the difference between Oracle database versions 12.2.0.1.191015 and 12.2.0.1.200114 this too follows the line of a low amount of differences.

There have been two spare parameters that have been changed to named undocumented parameters, and no data dictionary changes.

parameters unique in version 12.2.0.1.191015 versus 12.2.0.1.200114

NAME
--------------------------------------------------
_fifth_spare_parameter
_one-hundred-and-forty-eighth_spare_parameter

parameters unique in version 12.2.0.1.200114 versus 12.2.0.1.191015

NAME
--------------------------------------------------
_bug29825525_bct_public_dba_buffer_dynresize_delay
_enable_ptime_update_for_sys

On the C function side, there have been a group of AWR functions that have been removed and a group of SGA management functions, among other functions. There functions that have been added are random and diverse.