Fragmentation issues
Sergio Peres saw tables and indexes with many extents despite the auto_crsd task. Andreas Legner said auto_crsd capabilities are controlled by ph_threshold switches mostly off by default, and suggested raising the next extent size with ALTER TABLE for fast-growing tables. Art Kagel recommended oncheck -pT to see storage used. Sergio planned to check his settings.
Auto-generated by Claude from the posts below — may be imperfect; read the full thread.
Hi, I frequently see fragmentation in tables and indexes, even though I have activated the auto_crsd task there is still fragmentation. Are there any other tasks needed? How can I get the size of tables and indexes, including fragments? Thanks in advance for any help, SP ------------------------------ Sergio Peres AIRC Coimbra ------------------------------ #Informix
Hi Sergio, I guess you're talking about intra-partition fragmentation, so multiple / too many extents in partitions and the (auto-)defrag functionality? For the auto_crsd task, please be aware that its various capabilities can be turned on/off by specific switches in the ph_threshold table, and most are off by default (since the switches aren't even there in ph_threshold), if I'm right. Please refer to Scheduling data optimization for more details and/or ook at the related auto_crsd() SPL UDR definition in $INFORMIXDIR/etc/sysadmin/sch_tasks.sql for how exactly this works. Regarding size of partitions/tables/indices, I'm sure Art has this in one of his many scripts and utilities ;-) ... and it probably even will be in one of the discussions here. BR, Andreas ------------------------------ Andreas Legner ------------------------------
Thanks for Reply Andreas, I am afraid that I am not invoking the process in the correct way, however as I have tables that quickly get more than 30 extents I was convinced that these situations would be detected by auto_crsd... Thanks for the info, I'll check as I'm using the default values. Best regards, SP ------------------------------ Sergio Peres AIRC Coimbra ------------------------------
Sergio:
The best way to see how much storage your tables and indexes are taking up is to use oncheck -pT. That report will give you everything you need to know.
Art
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Art S. Kagel, President and Principal Consultant
ASK Database Management Corp.
www.askdbmgt.com
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So for "tables that quickly get more than 30 extents" you might want to (significantly) increase the "next size", by means of ALTER TABLE? ------------------------------ Andreas Legner ------------------------------