Sunil Raja said:
> Hi,
>
> Got some input from your previous mail.
>
> Please provide me a clarification regarding UPDATE STATISTICS
>
> The database contains only 3 tables, each table having less than 4
columns
> and no indexes.
>
> I ran the following command at my INFORMIX 9.4 using HP-UX 5.3 ( is the
> below command right ? ) :
>
> $ echo "update statistics" | dbaccess <database_name>
> Database selected.
>
> 1. What will the above command do ( what kind of update statistics will
it
> perform - low or high or medium ... Please explain ) ?
Low. Given you don't have indexes, that's all you need.
> 2. why this command is taking more time ( its more than 30 minutes, the
> process is not over ), for just a database with 3 tables and no indexes
?
How many rows in the tables? Bigger tables take more time.
> 3. If this command takes this much time, how can i check whether the
> statistics is working and how can i check whether the statistics of the
> table or index or database have been updated ?
Well, I really, REALLY think you need to read the manual. You've been sent
the links.
However, I can't see the point in doing update stats often unless the
table is very dynamic (i.e., grows or shrinks quickly).
> 4. will running update statistics several times, will affect the
database
> performance ?
Only run it when you need it.
> 5. will running update statistics several times, in different modes (
low,
> hhigh, medium ) for a table or index, will affec the database
performance
> ?
Not if you don't have indexes. If you don't have indexes, medium and high
are pointless.
> Please Guide me to proceed further.
>
> If you have time, please give me explanation, to update statistics, for
a
> database and table and index, each separately,
> and tell me why and where should we use low, high and medium.
Use low weekly as a guideline. Only use high and medium if you have
indexes, and then weekly is probably also a guideline. Medium and high
build data distributions, but they only get built if there are indexes.
> hy there are these types of confusing types and not a single command ( i
> like to know the purpose ) ?
> ( I saw the do***ents, but still couldnt understand ).
> How or where can i find whether the database or table or index has the
> statistics updated already or not ?
If you had indexes, then you could check dates in sysdistrib after doing
an update stats medium or high. But since you don't, you can't.
--
Bye now,
Obnoxio
"There were a myriad of problems which conspired to corrupt your reason
and rob you of your common sense. Fear got the best of you, and in your
panic you turned to the Labour Party. They promised you order, they
promised you peace, and all they demanded in return was your silent,
obedient consent."
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