RE: rule of thumb or words of wisdom for btree cleaners?
Forgot to mention, the the same settings can be done
with the following $ONCONFIG parameter:
BTSCANNER num=1,priority=low,threshold=50000,rangesize=10000
-Alexey
> -----Original Message-----
> From: owner-informix-list@iiug.org
[mailto:owner-informix-list@iiug.org] On
> Behalf Of Alexey Sonkin
> Sent: Friday, March 04, 2005 1:49 PM
> To: NormaJean; informix-list@iiug.org
> Subject: RE: rule of thumb or words of wisdom for btree cleaners?
>
> Norma,
>
> After a thorough investigation of how the BTSCANNER works,
> I can suggest a rule of a thumb:
>
> 1. ALWAYS change btscanner from the default 'leaf scan'
> to 'range scan' with a range scan threshold equal to
> 1-5 % of Informix cache, like:
>
> onmode -C rangesize 10000>
> 2. ALWAYS increase the 'number of dirty items' threshold
> to something MUCH higher then the default CRAZY value of 500:
>
> onmode -C threshold 50000>
> This threshold can be temporary changed to even higher value
> during massive data deletes
>
> 3. If (1) and (2) is set properly, don't care about allocating
> additional threads
>
> -Alexey
>
>
> > -----Original Message-----
> > From: owner-informix-list@iiug.org
> [mailto:owner-informix-list@iiug.org] On
> > Behalf Of NormaJean
> > Sent: Friday, March 04, 2005 10:26 AM
> > To: informix-list@iiug.org
> > Subject: rule of thumb or words of wisdom for btree cleaners?
> >
> > All,
> > Does anyone have a rule of thumb or words of wisdom regarding
> additonal
> > btree cleaners?
> > Looking at the output below it seems I could benefit from adding an
> > additional cleaner
> >
> > Stats reset at 8:30 AM
> > HPUX 11
> > $ onstat -C> >
> > IBM Informix Dynamic Server Version 9.40.FC2W4 -- On-Line -- Up 3> days
> > 14:50:17 -- 4460564 Kbytes
> >
> > Btree Cleaner Info
> > BT scanner profile Information
> > ==============================
> > Active Threads 1
> > Global Commands 0
> > Number of partition scans 23
> > Main Block 0xc0000000e0a97cc8
> > BTC Admin 0x0000000000000000
> >
> >
> > BTS info id Prio Partnum Key Cmd
> > 0xc0000000e0eb58b0 0 Low 0x055007F4 1 100000 Scan
index
> > Number of leaves pages scanned 10623920
> > Number of leaves with deleted items 122292
> > Time spent cleaning (sec) 22243
> > Number of index compresses 39214
> > Number of deleted items 4660843
> > Number of index range scans 0
> > Number of index leaf scans 259
> > Scan Type Leaf
> >
> >
> >
> > Darren Jacobs/Carmax
> >
>
>
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