IDS Forum

Re: Problem with extents on big table

Posted By: Art S. Kagel (Oninit)
Date: Thursday, 6 March 2008, at 12:25 p.m.

In Response To: RE: Problem with extents on big table (Lapeire, Jacques)

Lapeire, Jacques wrote:
> Thanks for the replies,
>
> In fact this dbspace consist of only 1 chunk and is meant only for this
> table.
>

Yes, if this table is the only one in the dbspace, then you can drop the
table (presumably you can recreate the data or you will export it
first), recreate the space by braking the disk into multiple chunks
(either by partitioning it or using offsets - separate partitions are
VERY MUCH preferred for maintenance reasons that will bite you one day
if you use offsets) and creating several dbspaces using those chunks.
Once that's done you can:

CREATE TABLE my_huge_table (
...
) FRAGMENT IN

<fragmentation expression>
...;

Fragmentation expressions are explained in the Guide to SQL Syntax. You
have two basic choices:

ROUND ROBIN fragmentation where the data is distributed roughly evenly
across <N> dbspaces/fragments or a calculated fragmentation expression.
The calculation can be as simple as:
all values of column colA < value1 in dbspace1, values between value1+1
and value2 in dbspace2 etc.
or complex like a hash:
all values of column colB where colB/7 = 1 in dbspace1, colB/7 = 2 in
dbspace2, ... colB/7 = 0 in dbspace7
or using a function:
all values of datecol where MONTH(datecol) = 1 in dbspace1, ...

Art S. Kagel
Oninit

> So I suppose I don't have to drop the complete database ? But only this
> dbspace ??
>
> Furtheron , I've never used fragmentation, can anyone explain in short
> the necessary steps ?
>
> Jacques
>
> -----Original Message-----
> From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On Behalf Of
> Art S. Kagel (Oninit)
> Sent: donderdag 6 maart 2008 17:29
> To: ids@iiug.org
> Subject: Re: Problem with extents on big table [11521]
>
> JACQUES LAPEIRE wrote:
>
>> Hi guys,
>>
>> anyone can help me on this ?
>>
>> Platform : Solaris 9 with IDS 9.40 FC7
>>
>> A dbspace "bdoc" has been created.
>> Onstat -d indicates a size of 400 000 000 2K pages,
>> of which still 382 122 223 2K pages free.
>>
>> A table document has been created
>> "in bdoc extent size 32000000 next size 32000000 lock mode page ;"
>> create unique index document1 on document (numdoc) using btree ;
>>
>> In sysextents we see a first size of 16000000 and the next is only
>>
> 777215
>
>
> Jacques,
>
> The largest single partition (or fragment) permitted in an IDS table is
> 16,777,215 pages! You cannot get more than that in a single partition.
> You will have to fragment your table into multiple fragments in order to
>
> have a table larger than 16,777,215 pages. In IDS 9.40 each of those
> fragments will need to be created in a different dbspace (in IDS 10.00
> and later you can create multiple fragments in a single dbspace). If
> you've created your one huge dbspace with all of your assigned disk
> space, you will have to drop the database and the dbspace and reorganize
>
> the space into several dbspaces then recreate this huge table fragmented
>
> across several of those dbspaces.
>
> Art S. Kagel
> Oninit
>
>
>> Millions of records have been inserted but now the application gets
>> an error : no more extents.
>>
>> I thought the limit was 4Tb in 9.40 ??
>>
>> What am I missing here ?
>>
>> Thanks for any reply
>>
>> Jacques Lapeire
>>
>>

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Messages In This Thread

• Problem with extents on big table
  JACQUES LAPEIRE -- Thursday, 6 March 2008, at 11:07 a.m.
  • Re: Problem with extents on big table
    DAVE GRIFFEN -- Thursday, 6 March 2008, at 11:24 a.m.
    • RE: Problem with extents on big table
      Robert Roussey(IT) -- Thursday, 6 March 2008, at 11:39 a.m.
      • Re: Problem with extents on big table
        Art S. Kagel (Oninit) -- Thursday, 6 March 2008, at 11:56 a.m.
  • Re: Problem with extents on big table
    Art S. Kagel (Oninit) -- Thursday, 6 March 2008, at 11:29 a.m.
    • RE: Problem with extents on big table
      Lapeire, Jacques -- Thursday, 6 March 2008, at 11:38 a.m.
      • Re: Problem with extents on big table
        Art S. Kagel (Oninit) -- Thursday, 6 March 2008, at 12:25 p.m.
        • RE: Problem with extents on big table
          Clifton Bean -- Thursday, 6 March 2008, at 12:43 p.m.

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