Re: Db2 and clob columns

[Jay Vaughn <jeffersonvaughn@xxxxxxxxx>]

So Charles,

We have a table developed to hold a request clob (5mb) and a response clob
(5mb) ONLY for storage and auditing purposes.
Not to run queries against.

We have been finding out that some off platform load tests are being
performed and even though the api calls to put rows in this table should
have 1mb or less requests/responses, we are maxing out the DASD on that
test box and this table ends up with 821G of data.

Again our requests/responses should be well under 1mb each.

So is this table just a bad idea or are we simply over dominating the box
with our load test volume?

Next time this happens I really want to look at the rows and see what these
columns have in them.

thanks

Jay








On Mon, Apr 15, 2024 at 6:51 PM Jay Vaughn <jeffersonvaughn@xxxxxxxxx>
wrote:

> Thanks Charles.
>
> I’lllook into the allocate but big relief on the storage concern.
>
> Jay
>
> > On Apr 15, 2024, at 5:44 PM, Charles Wilt <charles.wilt@xxxxxxxxx>
> wrote:
> > Nope...
> >
> > variable length data is stored in the overflow section of the table...
> >
> > Downside of that is that when you read the row, it takes 2 I/Os.  One for
> > the row space and one for the overflow.
> >
> > If you were mostly writing less that 32k, I'd tell you to take a look at
> > the ALLOCATE clause.  That does cause space to be reserved in the
> standard
> > table space.  Which wastes space, but then the data only needs 1 I/O to
> be
> > read.
> >
> > Charles
> >
> >
> > > On Mon, Apr 15, 2024 at 2:20 PM Jay Vaughn <jeffersonvaughn@xxxxxxxxx>
> > > wrote:
> > >
> > > Let’s say I have a table with a 5mb clob column.
> > >
> > > Most of my transactions that write to the table mostly consist of 64k
> and
> > > less chars written to the clob but we want to reserve the much higher
> > > storage allocation for when we need it
> > >
> > > When the 64k chars are written to that clob on the row, the entire 5mb
> of
> > > storage is not written to disk is it??
> > >
> > > Tia
> > >
> > > Jay
> > >
> > > Sent from my iPhone
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