Re: Duplicates in systabnames?
Omar Muñoz wrote:
> Hi.
>
> I was using one of the IIUG scripts to calculate
> better sizes for extents (tabextplan) and I realized
> that one table gave me a different result in
> comparison to oncheck -pt. Researching, i found out
> that there are two record in sysmaster:systabnames
> with the same tabname and different partnum, and the
> table I'm talking about is not fragmented. Is that
> kind of duplicate something normal? should I be worry
> about corruption on database?
>
No. Not corruption but more likely one record is for the table and the
other for a semi-detached index. These were created by some IDS
versions (7.30 and 9.21 IB) when an index was created without an IN
clause. You can verify this by looking closer at the sysptnhdr records
for the two partnums. One will show that npused is approximately equal
to npdata while the other will show that npdata is zero. This latter is
the index partition. If you are running a later release of IDS this
just means that the index in question was created by an earlier version
and has never been rebuilt under the newer release.
Prior to these IDS versions indexes that were not explicitely detached
(ie had no IN clause) were fully attached to the table they index,
meaning that their pages were interleaved with data pages extent by
extent. In even earlier versions of Informix index and data pages were
interleaved within the same extents. Semi-detached indexes were an
initial attempt to gain some of the performance improvements of fully
detached indexes without requiring users to specify an IN clause. Later
releases behave as if a default IN clause specifying the table's home
dbspace had been supplied.
Art S. Kagel
Oninit
> Thanks in advance
>
> Omar Muñoz
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