Re: Migrating 9i to 10g performance issues
- From: "Andrew Kerber" <andrew.kerber@xxxxxxxxx>
- To: "Howard Latham" <howard.latham@xxxxxxxxx>
- Date: Tue, 25 Mar 2008 09:19:50 -0500
I have found that large table exports are much easier than imports, set
direct=y, do the export on the local server, then copy the export to your
destination server to do the import. Also, if you build the indexes as a
separate import job it works better.
For best performance, here is what I found worked best, Do all of this with
multiple streams:
Export the tables, (rows=n) to get your table definitions.
export rows=y, direct=y to get the data
Import the table definitions (rows=n, constraints=n, indexes=n).
Import the tables, constraints=n and indexes=n, rows=y
Then import again, rows=n indexes=y constraints=y
On Tue, Mar 25, 2008 at 9:15 AM, Howard Latham <howard.latham@xxxxxxxxx>
wrote:
> I found that large tables and exp are difficult. also exp/imp means you
> have to rebuild the indexes -
> that aint arf slow - even for a small db!
>
>
> On 25/03/2008, Andrew Kerber <andrew.kerber@xxxxxxxxx> wrote:
> >
> > It can be done with export import. If you use export import, use
> > multiple streams, and disable all constraints before the import. Enable the
> > constraints when all imports are complete. That includes primary key
> > constraints. It takes planning and practice to use that method, but it will
> > work. The advantage is that most DBA's have a good understanding of
> > exp/imp.
> >
> > Datapump will also work. Datapump will run in parallel mode, but it has
> > some bugs in 10g.
> >
> > If you have blobs/clobs they will be your single largest time consumer.
> > If you use export/import do not commit until all the blobs/clobs are
> > imported. I have done this a few times, and at one point I wrote something
> > for a mass delete using an export (basically, export the rows to keep,
> > truncate the table, and import). It was nice since it rebuilt the table and
> > indexes at the same time it did the export/import.
> >
> > On Tue, Mar 25, 2008 at 6:56 AM, Sandra Becker <sbecker6925@xxxxxxxxx>
> > wrote:
> >
> > > Source DB: Dell server, RHEL4, 12G RAM, Oracle 64 bit 9.2.0.8 SE1,
> > > little endian
> > > Target DB: IBM VM on series z9, SLES10, 4G RAM, Oracle 10.2.0.3 EE,
> > > big endian
> > > Database is just shy of 1 terabyte in size--70 percent of data is in a
> > > single table; total of 212 tables.
> > > 12 very large tables, including the monster--most have no column, like
> > > a static date, that can be used to logically break the data into
> > > "partitions".
> > >
> > > I'm working on procedures to move our production database from the
> > > Dell to the IBM. My tests so far indicate that I'm going to need more
> > > than
> > > 24 hours. Management, in their infinite wisdom, is insisting that it be
> > > done in less than 8. It will take as long as it takes, but I'm wondering
> > > what I can do to speed things up. So far I've done the following:
> > >
> > > 1) exp/imp - too slow overall
> > > 2) plsql that commits at regular intervals, depending on the size of
> > > the table - works very well for all tables under 1M; can load 111 tables
> > > in
> > > under 2 hours using 2 concurrent sessions. Works for larger tables, but
> > > obviously takes much longer. I had 2 sessions doing tables under 1M and 2
> > > doing tables between 1M and 100M concurrently. Didn't try for the 12
> > > tables
> > > over 100M.
> > > 3) Direct-path insert - used on the table holding 70 percent of the
> > > data. Four months ago I insisted this table have a static date column
> > > added. I can logically break the data loads down by date--they want the
> > > most current data loaded first, the remainder can be done over a period of
> > > days. This is working reasonably well, but having done this same thing
> > > once
> > > before on this table, I know it will take about a month to get all the
> > > data
> > > moved based on the constraints I'm working under--can't be done during
> > > core
> > > business hours, etc.
> > > 4) I put the target database in noarchivelog mode for my testing. Is
> > > this a wise move for migrating production during the go live?
> > >
> > > Manage has suggested that I leave off old data and load it later.
> > > Doesn't work with 95 pecent of the tables because of their structure and
> > > foreign key constraints. They also suggested I use both the primary and
> > > the
> > > standby databases to read from. No way to test this until I go
> > > live--constraints again--although this actually was part of my plan from
> > > the
> > > beginning. Will too many concurrent sessions loading data slow things
> > > down
> > > too much? What would I look at to determine this? 10g is new to me so
> > > I'm
> > > not familiar with all the features yet and may be missing something
> > > significant.
> > >
> > > Any suggestions are appreciated, other than telling management what
> > > they can do with their time constraint. (Already did that.)
> > >
> > > Thanks.
> > >
> > > Sandy
> > >
> >
> >
> >
> > --
> > Andrew W. Kerber
> >
> > 'If at first you dont succeed, dont take up skydiving.'
>
>
>
>
> --
> Howard A. Latham
>
--
Andrew W. Kerber
'If at first you dont succeed, dont take up skydiving.'
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