Re: SQL PLan Cache

PMR Time? That is a very good question to ask Rochester. I also understand
the iASP as an entirely separate DB2 instance so the query engine should do
the same it does when IPLing...

On Tue, Dec 18, 2018 at 2:28 PM DrFranken <midrange@xxxxxxxxxxxx> wrote:

Just the iASP would be flashed. Vary off, End flash copy, Restart flash
copy, Vary on.

Because the iASP is a separate database it makes me think the system may
clear all the entries for that iASP in this sequence.

You are correct that an IPL would clear it but we would not be doing an
IPL. However if I understand everything correctly we are 'sorta' doing
an IPL of the database on the iASP.

- Larry "DrFranken" Bolhuis

www.Frankeni.com
www.iDevCloud.com - Personal Development IBM i timeshare service.
www.iInTheCloud.com - Commercial IBM i Cloud Hosting.

On 12/18/2018 12:23 PM, Roberto José Etcheverry Romero wrote:

Dr, when you say "re flash" do you mean an iASP or an entire "I flash the
LPAR complete, load source and all" Flashcopy?. If iASP I have NO idea
where the plan cache lives and worse, what would happen if the underlying
data changes and the plan cache isn't aware of it (maybe invalidate the
cache when doing a varyoff?), I assume that an entire Flashcopy would

bring

the plan cache from the LPAR but, doesn't the plan cache expire on IPL?

Roberto


On Tue, Dec 18, 2018 at 2:15 PM DrFranken <midrange@xxxxxxxxxxxx> wrote:

Suppose I have a Storwize full of SSDs. I have all my data in iASP
because I use PowerHA. I already do flash copies for other reasons such
as Backup and training. However there are a group of folks that do
ad-hoc queries all day from windows servers and they often submit a half
a kabilion of these things all at once. THEN they have the nerve to
complain that they get different totals when they compare. Well querying
the data at different points in the day will do that on live data, DUH!

Flash copy to the rescue I believe. Now they can query last night's
data. Also it nicely boxes them into x CPU and y Memory. And while the
I/O itself is the same physical disks that's not been a problem for
performance.

QUESTION though is what happens to the plan cache for all their queries
when I re-flash the disk. Does it get flushed in a flash? That would
sorta suck.

--

- Larry "DrFranken" Bolhuis

www.Frankeni.com
www.iDevCloud.com - Personal Development IBM i timeshare service.
www.iInTheCloud.com - Commercial IBM i Cloud Hosting.
--
This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing

list

To post a message email: MIDRANGE-L@xxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
visit: https://lists.midrange.com/mailman/listinfo/midrange-l
or email: MIDRANGE-L-request@xxxxxxxxxxxx
Before posting, please take a moment to review the archives
at https://archive.midrange.com/midrange-l.

Please contact support@xxxxxxxxxxxx for any subscription related
questions.

Help support midrange.com by shopping at amazon.com with our affiliate
link: https://amazon.midrange.com

--
This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing list
To post a message email: MIDRANGE-L@xxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
visit: https://lists.midrange.com/mailman/listinfo/midrange-l
or email: MIDRANGE-L-request@xxxxxxxxxxxx
Before posting, please take a moment to review the archives
at https://archive.midrange.com/midrange-l.

Please contact support@xxxxxxxxxxxx for any subscription related
questions.

Help support midrange.com by shopping at amazon.com with our affiliate
link: https://amazon.midrange.com