Thanks you Mark! I appreciate your thoughts and insight. Going to
incorporate this as much as possible to see what it buys me.
On Fri, Jul 27, 2018 at 1:04 PM Mark W. Farnham <mwf@xxxxxxxx> wrote:
You are probably correct. An insert dop of 1 might even be best so there
is a single insert point for each table and thus no contention for above
the high water mark blocks (which is presumably the beginning since you’re
using a new table for each insert target.
Unlike online move, in this model your original data source still exists,
so you may persuade your administrators to give you new time period based
tablespaces that are initially NOT force logged and back them and ship them
well before the source goes away. Remember, since exchange doesn’t move the
data, these new tablespaces are where the data will remain. If you’re
appending to only one table per tablespace at a time, then dbwr is going to
have contiguous blocks or compression units to write. I don’t know how much
that might speed things up on an Exadata. On older disk tech it can be a
lot.
If there is a known best order for both compression and query block
clustering (or even one or the other), this is the time to do it. With the
way HCC works this can save a lot of space if commonly duplicated column
values gain a high fan-in per compression unit. With zone maps this can
dramatically reduce the compression units needed to be unpacked and
delivered at query time. You get that forever for any partitions that have
become quiescent with age.
Good luck!
mwf
*From:* oracle-l-bounce@xxxxxxxxxxxxx [mailto:
oracle-l-bounce@xxxxxxxxxxxxx] *On Behalf Of *Woody McKay
*Sent:* Thursday, July 26, 2018 7:58 PM
*To:* keyantech@xxxxxxxxx
*Cc:* ORACLE-L
*Subject:* Re: Huge Table Insert - take long time?
Ya got me thinking about the "load data by partition" idea...
I wonder if instead of insert dop 16 from select dop 16, what if I have
say 50 nonpartitioned tables (one for every partition) and dop4 insert into
the from *_old partition () all at the same time. Then do a partition
exchange from the 50 nonpartitioned tables to the main fully partitioned
table? The exchange is quick since it is just a data dictionary change.
This may be faster because the amount of DOP is higher. Maybe less
exchange waits? I'm assuming that the DOP 16 can't work on all 50
partitions all together as efficiently as loading all 50 nonpartitioned
tables?
Got me thinking...
On Mon, Jul 23, 2018 at 8:15 PM Karthikeyan Panchanathan <
keyantech@xxxxxxxxx> wrote:
What is the partition type involved here?
One option you can load data by partition into intermediary table(with new
columns) and exchange. This way you can run parallel sessions for each
partition and before exchange new table you can build at partition level.
You mentioned other db, have you thought about moving data from other db
to prod using data-pump?
Karth
Sent from my IPhone
On Jul 23, 2018, at 7:52 PM, Woody McKay <woody.mckay@xxxxxxxxx> wrote:
Hi gurus, I'm fishing for creative thoughts here...
12.1.0.2 RAC on Exadata with forced logging for standby
There's a refactoring process: (subpartitioned tables with millions to a
few billions of rows)
1. rename the main table to main_old
2. create the new_main table (no indexes or constraints at this point)
3. set table prefs for concurrent incremental stats
4. enable parallel dml
5. insert into new_main from main_old using APPEND PARALLEL 16 (note: most
tables are compressed)
6. create a PK or an index (as needed) on new_main
7. gather table stats on new_main
The insert in Step 5 took 9.5 hours... Total refactor process time was
about 13 hours.
Is there anything you can think of to make this process any faster?
I assume the APPEND hint isn't doing much because the DB has FORCE
LOGGING. Guessing alter table nologging wouldn't do much either. Can't
exchange from old to new since new mostly likely had columns added.
I've mentioned using alter table if we are only adding a few columns, but
the production DBA's are worried about chained-rows, fragmentation,
possible explain plan changes, etc. I'm not sure if they are justified in
their thoughts.
I've thought of doing the refactor in a diff DB (where I can truly have
nologging) and use transportable tablespace, but don't think that would be
any better.
Any Thoughts or ideas to try?
Thanks, as always - Woody
--
Sincerely,
WoodyMcKay
