2026-03-12 21:01:38

2026-03-12 22:01:38 +01:00
parent 3bd1db26cc
commit 26296b6d6a
336 changed files with 27507 additions and 0 deletions
--- a/histograms/histogram_03.txt
+++ b/histograms/histogram_03.txt
@@ -0,0 +1,120 @@
+create pluggable database NEREUS admin user PDB$OWNER identified by secret;
+alter pluggable database NEREUS open;
+alter pluggable database NEREUS save state;
+
+alter session set container=NEREUS;
+show pdbs
+show con_name
+
+grant sysdba to adm identified by secret;
+
+alias NEREUS='rlwrap sqlplus adm/secret@bakura/NEREUS as sysdba'
+
+create tablespace USERS datafile size 32M autoextend ON next 32M;
+alter database default tablespace USERS; 
+
+create user HR identified by secret
+  quota unlimited on USERS;
+
+grant CONNECT,RESOURCE to HR;
+grant CREATE VIEW to HR;
+
+wget https://raw.githubusercontent.com/oracle-samples/db-sample-schemas/main/human_resources/hr_cre.sql
+wget https://raw.githubusercontent.com/oracle-samples/db-sample-schemas/main/human_resources/hr_popul.sql
+
+connect HR/secret@bakura/NEREUS
+
+spool install.txt
+@hr_cre.sql
+@hr_popul.sql
+
+
+alter user HR no authentication;
+
+select /*+ GATHER_PLAN_STATISTICS */
+	  emp.FIRST_NAME
+	, emp.LAST_NAME
+	, dept.DEPARTMENT_NAME
+from 
+	HR.EMPLOYEES emp,
+	HR.DEPARTMENTS dept
+where 
+	emp.DEPARTMENT_ID = dept.DEPARTMENT_ID   
+order by 
+	FIRST_NAME,
+	LAST_NAME
+/
+
+select * from table(dbms_xplan.display_cursor(null,null,'ALLSTATS LAST  +PEEKED_BINDS +PARALLEL +PARTITION +COST +BYTES'));
+
+exec dbms_stats.delete_table_stats('HR','EMPLOYEES');
+exec dbms_stats.delete_table_stats('HR','DEPARTMENTS');
+
+alter system flush shared_pool;
+
+exec dbms_stats.gather_table_stats('HR','EMPLOYEES', method_opt=>'for all columns size SKEWONLY');
+exec dbms_stats.gather_table_stats('HR','DEPARTMENTS', method_opt=>'for all columns size SKEWONLY');
+
+exec dbms_stats.gather_table_stats('HR','EMPLOYEES', method_opt=>'for all columns size 254');
+exec dbms_stats.gather_table_stats('HR','DEPARTMENTS', method_opt=>'for all columns size 254');
+
+
+
+select column_name,num_distinct,density,num_nulls,num_buckets,sample_size,histogram  
+from dba_tab_col_statistics  
+where owner='HR' and table_name='EMPLOYEES' and column_name='DEPARTMENT_ID'; 
+
+select endpoint_value as column_value, 
+endpoint_number as cummulative_frequency, 
+endpoint_number - lag(endpoint_number,1,0) over (order by endpoint_number) as frequency 
+from dba_tab_histograms 
+where owner='HR' and table_name='EMPLOYEES' and column_name='DEPARTMENT_ID'; 
+
+select column_name,num_distinct,density,num_nulls,num_buckets,sample_size,histogram  
+from dba_tab_col_statistics  
+where owner='HR' and table_name='DEPARTMENTS' and column_name='DEPARTMENT_ID'; 
+
+select endpoint_value as column_value, 
+endpoint_number as cummulative_frequency, 
+endpoint_number - lag(endpoint_number,1,0) over (order by endpoint_number) as frequency 
+from dba_tab_histograms 
+where owner='HR' and table_name='DEPARTMENTS' and column_name='DEPARTMENT_ID'; 
+
+
+break on report skip 1
+compute sum of product on report
+column product format 999,999,999
+ 
+with f1 as (
+select
+        endpoint_value                                                            value,
+        endpoint_number - lag(endpoint_number,1,0) over(order by endpoint_number) frequency
+from
+        dba_tab_histograms
+where
+        owner='HR'
+and     table_name  = 'EMPLOYEES'
+and     column_name = 'DEPARTMENT_ID'
+order by
+        endpoint_value
+),
+f2 as (
+select
+        endpoint_value                                                            value,
+        endpoint_number - lag(endpoint_number,1,0) over(order by endpoint_number) frequency
+from
+        dba_tab_histograms
+where
+		owner='HR'
+and     table_name  = 'DEPARTMENTS'
+and     column_name = 'DEPARTMENT_ID'
+order by
+        endpoint_value
+)
+select
+        f1.value, f1.frequency, f2.frequency, f1.frequency * f2.frequency product
+from
+        f1, f2
+where
+        f2.value = f1.value
+;