Analyze_table Vs Analyze_Schema

[fugazi]

Hi,

I want to do a complete analyze of all tables and index in a schema. Do I use analyze_table on every table or do I use Analyze_schema (taht will analyze every tables and index under the shcema)?

Which one is less consuming for the CPU and the system ?

Thank for your help !

[Halo]

Use analyze_schema.

[santoshym]

Hi

Right use analyze_schema this is less time consuming for you in one command it will analyze all the objects in the schema where if you analyze using analyze_table you will have to do it manually one by one or write a script put all the analyze_table statements in it and then execute the file.I feel both of them will consume the same CPU resources

Regards

[fugazi]

Thank You very much !!! I really appreciate.

[chrisrlong]

However, analyze_schema is a serial process. If you write your own, you can launch several jobs simultanwously that can each analyze a different set of tables. This is, AFAIK, the most efficient way to analyze the entire schema.

- Chris

[pando]

with DBMS_STATS you can analyze the schema in parallel

[sonaliak]

I read that analyze_schema can sometimes lock the whole system...is this true ? how do you avoid that ?

I have these 2 scripts for analyze_schema..

BEGIN

sys.dbms_utility.analyze_schema ( '&OWNER','COMPUTE');

END ;

/
BEGIN

dbms_utility.analyze_schema ( '&OWNER', 'ESTIMATE', NULL, 5 ) ;

END ;

/

Whats the difference between ESTIMATE and COMPUTE...
We always do compute here. When will you do Estimate ?
When do you do validate structure ?

Also if you do analyze table it does analyze indexes too right, I saw the new date in user_indexes tables..just wanted to confirm this.

If say I analyze all of my tables today i.e May 21st... and I do lots of DML on that database. For how long will they be using cost based optimizer ? In other words when do I need to analyze all my tables again ?


thanks
Sonali