Re: PCTFREE & PCTUSED

mike.borden_at_gmail.com (tilwenbr_at_netscape.net) wrote in message news:<2d4a7b11.0410050819.666c3e1c_at_posting.google.com>...
> Ok, I have a question about PCTFREE & PCTUSED.
>
> First we are on 8.1.7.4 on VMS.
>
> When these parameters are changed do they affect immediately?
> According to the concepts guide it states this:
> When altering the data block space usage parameters (PCTFREE and
> PCTUSED) of a table, note that new settings apply to all data blocks
> used by the table, including blocks already allocated and subsequently
> allocated for the table. However, the blocks already allocated for the
> table are not immediately reorganized when space usage parameters are
> altered, but as necessary after the change. The data block storage
> parameters are described in "Managing Space in Data Blocks".
>
> I interpret this as that we do not have to reorganize the table for
> these settings to take affect on the blocks already allocated;
> however, they do not take immediate affect until "later" or the block
> reaches the new "threshold" of these settings.
>
> Am I reading this correctly?

Yes. But note that if you unload and reload the table it will apply to everything.

So for example, if you have a lot of full blocks, and change these settings, nothing will happen until a given block is modified or inserted to. But if you export/import, the table will be much larger because of all the free space that must now be maintained. This and other strange effects can be surprising if you don't think it through.  You must be aware of how data is inserted and updated by the application.

>
>
> BTW, this is a vendor db, so we can not go to DM tablespaces yet. :(.

I hope you mean LMT, and why not?

>
> Mike

jg

--
@home.com is bogus.
"I still don't take showers ..." - Jeanette Helen Morrison, aka Janet
Leigh.
1927 - 2004 RIP