IDS Forum

Re: undocumented parameters

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----- Original Message -----
From: Ricardo Manzo <Ricardo.Manzo@cosan.com.br>
At: 3/12 16:20

> Hi all ,
>
> Does anybody know the meaning about the parameters below and how does it
affect
> performance ?

Yes...

> DD_HASHSIZE
Not to forget: DD_HASHMAX

The above control the size of the in-memory Data Dictionary cache, the current
settings and contents are reported by onstat -g dic. DD_HASHSIZE is the number
of hash buckets in the cache and MUST be a prime number, it is reported as
'Number of lists'. IB the default is 127. DD_HASHMAX is the number of slots in
each hash bucket and should be a small integer (default 31), it is reported as
'Maximum list size'. If you have close to or more than DD_HASHMAX * DD_HASHSIZE
active tables in your instance, or access large numbers of remote tables that
will swell the local cache, you should increase these values, at least
DD_HASHSIZE. If you access many tables with similar names you should increase
DD_HASHMAX to widen the buckets.

> DS_HASHSIZE
> DS_POOLSIZE

The above control the size of the in-memory Data Distribution cache, the current
settings are reported by onstat -g dsc. The rules are similar as for the DD_
parameters. DS_HASHSIZE MUST be a prime number (default 31) and is called
'Number of lists' in onstat, this is the number of hash buckets in the
distribution cache. DS_POOLSIZE is the number of number of entries total in the
distribution cache integer (default 127) and is reported by name in the onstat
output.

> PC_POOLSIZE
> PC_HASHSIZE


The above control the size of the in-memory Stored Procedure cache, the current
settings are reported by onstat -g prc. The rules are similar as for the DD_
parameters. PC_HASHSIZE MUST be a prime number (default 31) and is called
'Number of lists' in onstat, this is the number of hash buckets in the procedure
cache. PC_POOLSIZE is the number of number of entries total in the procedure
cache integer (default 127) and is reported by name in the onstat output.

This is documented in the Administrator's Guide and in the Performance Guide.

Art S. Kagel


> Thanks
>
>
> Ricardo

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