index rebuild can screw app??

[farrokhp]

Is it possible the alter index rebuild make the application too slow? After this command do we need to do analyze index? I guess
all stat for CBO will gone after this command? what's happened?

[mallard]

Rebuild index should make app run better, if anything. This would be because the rebuild re-organizes the index....removed deleted leafs, etc. It probably wouldn't hurt to analyze after a rebuild, but I don't think it's a must.

[mrvajrala]

Analyzing index will infact improve the performance and I do analyze of some of the schemas in my database every day .

My options are :
estimate , 15%

I use DBMS_UTILITY.ANALYZE_SCHEME

rebuilding indexes is not a daily activity , but analyzing should be a daily one in order to provide a right feed to CBO to improve performance.

Thanks,
Madhu

[marist89]

Originally posted by mrvajrala
but analyzing should be a daily one in order to provide a right feed to CBO to improve performance.

Depends on how often the characteristics of your data changes.

I was once at a site where they had about 3 years of historical data. They loaded several million rows a day, but that didn't change the characteristics of the data. They computed statistics once every 6 months.

[farrokhp]

Guys, what's happened in my case was after I rebuild the index the application get slow significantly ( from other floors folks called me immediately and I paniced !! ) then I search google and find out someboy said do analyze tabel ... for all indexes and I did that and BOOM ... application get back to normal speed , no more complains I recieved. NOWHERE in Oracle Doc this is mention. Do you know why?? i really paniced!