1. Optimizer Statistics Julian Dyke Independent Consultant Web Version
juliandyke.com

2. Agenda Statistics Strategies ANALYZE DBMS_STATS
ANALYZE versus DBMS_STATS
System Statistics
Automatic Statistics Collection
Statistics History
Manual Statistics
Partition Statistics
Oracle 11g Enhancements

3. Statistics Strategies

4. Statistics Strategies Introduction
Only gather statistics when object has changed significantly
Consider generating manual statistics for:
Very large objects
Temporary tables
Highly volatile tables
Try to collect statistics during a specified window
Do not execute SQL statements during statistics collection
Use DBMS_STATS parallelism
Review sample sizes for very large objects
In complex databases do not rely on Auto job
Unpredictable collection behaviour / duration
Unpredictable execution plan changes
See Metalink Note Statistics Gathering; Frequency and Strategy

5. ANALYZE

6. ANALYZE Introduction SQL statement Introduced in Oracle 7.0
Collects object statistics for Cost Based Optimizer
Initially collected statistics on tables and indexes
Subsequently on histograms
Advantages
Online analyze - Oracle 9.0 and above
Optionally validates structure of tables, indexes and clusters
Optionally detects chained / migrated rows
Disadvantages
Serial statistics collection only
Limited partition-awareness

7. ANALYZE VALIDATE STRUCTURE
Syntax is
ANALYZE INDEX <index_name> VALIDATE STRUCTURE;
Populates session-level dynamic performance views
INDEX_STATS
INDEX_HISTOGRAMS
Reports index statistics including:
height
number of leaf blocks
number of branch blocks
number of distinct keys
Reports space released by deletions
Use to determine when to coalesce or rebuild index
Recommends index compression columns
Use to determine which indexes should be compressed

8. ANALYZE VALIDATE STRUCTURE ONLINE
Introduced in Oracle 9.0.1
Syntax is
ANALYZE INDEX <index_name> VALIDATE STRUCTURE ONLINE;
ONLINE option
only checks structure
does not require TM (DML) lock
does not populate INDEX_STATS or INDEX_HISTOGRAM

9. DBMS_STATS

10. DBMS_STATS Introduction
PL/SQL supported package
Introduced in Oracle 8.1.5
In Oracle 11.1 there are 107 subroutines
Defined in $ORACLE_HOME/rdbms/admin/dbmsstat.sql
Advantages
Parallel statistics collection
Partition-awareness
Disadvantages
Cannot perform structure validation
Cannot detect chaining / migration

11. DBMS_STATS Gathering Statistics
Statistics can be gathered using the following subroutines:
GATHER_DATABASE_STATS
GATHER_SCHEMA_STATS
GATHER_TABLE_STATS
GATHER_INDEX_STATS
These routines allow you to specify:
Sample size
Granularity (partitioned tables only)
Histogram policy
Cursor invalidation policy

12. DBMS_STATS Deleting Statistics
Statistics can be deleted using the following subroutines:
DELETE_DATABASE_STATS
DELETE_SCHEMA_STATS
DELETE_TABLE_STATS
DELETE_INDEX_STATS
DELETE_COLUMN_STATS
DELETE_TABLE_STATS includes
CASCADE_PART - optionally delete partition statistics
CASCADE_COLUMNS - optionally delete column statistics
CASCADE_INDEXES - optionally delete index statistics
DELETE_INDEX_STATS, DELETE_COLUMN_STATS include:

13. DBMS_STATS Statistics Tables
Used to
export / import statistics
store object statistics values PRIOR to GATHER operations
To create a statistics table use CREATE_STATS_TABLE. For example:
dbms_stats.create_stats_table ( ownname => 'SYSTEM', tabname => 'STATS1', tblspace=> 'SYSAUX' );
To drop a statistics table use DROP_STATS_TABLE
To drop a statistics table use DROP_STATS_TABLE. For example:
dbms_stats.drop_stats_table ( ownname => 'SYSTEM', tabname => 'STATS1' );

14. DBMS_STATS Exporting and Importing Statistics
Statistics can be exported to a statistics table using:
EXPORT_COLUMN_STATS
EXPORT_DATABASE_STATS
EXPORT_INDEX_STATS
EXPORT_SCHEMA_STATS
EXPORT_TABLE_STATS
Statistics can be imported from a statistics table using:
IMPORT_COLUMN_STATS
IMPORT_DATABASE_STATS
IMPORT_INDEX_STATS
IMPORT_SCHEMA_STATS
IMPORT_TABLE_STATS
To transfer the statistics to another database export and import the statistics table

15. DBMS_STATS OPTIONS parameter
Specifies how to determine which objects to gather statistics for:
GATHER - gather statistics for all objects
GATHER AUTO - gather statistics for all objects needing new statistics
GATHER STALE - gather statistics for all objects having stale statistics
GATHER EMPTY- gather statistics for all objects having no statistics
LIST AUTO - list objects needing new statistics
LIST STALE - list objects having stale statistics
LIST EMPTY - list objects having stale statistics
The OBJLIST parameter must be specified as an OUT parameter for the LIST options
GATHER STALE and GATHER EMPTY can also return a list of objects if this parameter is specified

16. DBMS_STATS OPTIONS parameter
If GATHER STALE is specified statistics will be gathered for objects where at least 10% of rows have changed
Total of INSERTS, UPDATES and DELETES since last statistics collection
In Oracle 10g percentage is fixed at 10%
In Oracle 11g percentage is user-configurable

17. DBMS_STATS Stale Statistics
In Oracle 10.1 and above table modification statistics:
are enabled if STATISTICS_LEVEL is TYPICAL or ALL
are disabled if STATISTICS_LEVEL is BASIC
are collected in the SGA
are automatically flushed to SYS.MON_MODS$
by SMON background process
every 15 minutes to SYS.MON_MODS$
if a significant number of rows has changed (possibly 10%)
can be manually flushed to SYS.MON_MOD$ using:
DBMS_STATS.FLUSH_DATABASE_MONITORING_INFO
are reported in DBA_TAB_MODIFICATIONS

18. DBMS_STATS Stale Statistics
SYS.MON_MODS$ has the following columns:
Column Name
Data Type
OBJ#
NUMBER
INSERTS
UPDATES
DELETES
TIMESTAMP
DATE
FLAGS
DROP_SEGMENTS

19. DBMS_STATS Stale Statistics
In Oracle 8i, table modification monitoring can only be enabled manually using:
ALTER TABLE <table_name> MONITORING; ALTER TABLE <table_name> NOMONITORING;
In Oracle 9i, table modification monitoring can also be enabled using
DBMS_STATS.ALTER_SCHEMA_TAB_MONITORING ('<owner>',TRUE); DBMS_STATS.ALTER_DATABASE_TAB_MONITORING (TRUE);
Reported in DBA_TABLES.MONITORING
In Oracle 10.1 and above MONITORING clause is deprecated and ignored

20. DBMS_STATS ESTIMATE_PERCENT Parameter
Specified using ESTIMATE_PERCENT parameter in
GATHER_DATABASE_STATS
GATHER_DICTIONARY_STATS
GATHER_INDEX_STATS
GATHER_SCHEMA_STATS
GATHER_TABLE_STATS
Valid range is to 100
NULL means COMPUTE
Default (10.2) is DBMS_STATS.AUTO_SAMPLE_SIZE
Oracle determines sample size automatically
Default can be changed using SET_PARAM procedure

21. DBMS_STATS GRANULARITY Parameter
Only relevant for partitioned objects
ALL - gather global, partition and subpartition statistics
AUTO - determine granularity based on partitioning type.
DEFAULT - gather global and partition-level statistics. Now obsolete. Use GLOBAL AND PARTITION instead
GLOBAL - gather global statistics
GLOBAL AND PARTITION - gather global and partition-level statistics
PARTITION - gather partition-level statistics
SUBPARTITION - gather subpartition-level statistics
In Oracle 10.2 default is AUTO (not DEFAULT)

22. DBMS_STATS NO_INVALIDATE parameter
In earlier versions ANALYZE and DBMS_STATS gather procedures always invalidated cursors referencing affected object
In Oracle 10.1 and above, invalidation can be controlled using NO_INVALIDATE parameter
TRUE - do not invalidate dependent cursors
FALSE - invalidate dependent cursors
DBMS_STATS.AUTO_INVALIDATE (default) - Oracle determines whether to invalidate dependent cursors or not.
In Oracle 10.2 the default value can be changed using SET_PARAM procedure
Only relevant for DBMS_STATS gather procedures
ANALYZE always invalidates analyzed objects

23. DBMS_STATS Data Dictionary Statistics
Oracle recommends that data dictionary statistics are collected in Oracle and above
Subroutines are:
GATHER_DICTIONARY_STATS
DELETE_DICTIONARY_STATS
EXPORT_DICTONARY_STATS
RESTORE_DICTIONARY_STATS
In Oracle 9i data dictionary statistics should only be collected using:
dbms_stats.gather_schema_stats (ownname => 'SYS',cascade=> TRUE);
In Oracle 9i data dictionary statistics can be deleted using:
dbms_stats.delete_schema_stats (ownname => 'SYS');
See Metalink Note
Note ANALYZE should not be used with tables owned by SYS. See Metalink Note

24. DBMS_STATS Fixed Object Statistics
In Oracle 10.1 and above Oracle recommends that statistics are collected on fixed objects
These include X$ and V$ views
Subroutines include:
GATHER_FIXED_OBJECTS_STATS
DELETE_FIXED_OBJECTS_STATS
EXPORT_FIXED_OBJECT_STATS
RESTORE_FIXED_OBJECTS_STATS
For example:
dbms_stats.gather_fixed_objects_stats;
According to Metalink Note fixed object statistics can be collected and stored in a temporary table and subsequently written to the data dictionary.
To create the temporary statistics table use:
EXECUTE dbms_stats.create_stat_table ('SYS','FIXED_STATS');
To collect statistics and to store them in the temporary statistics table use:
EXECUTE dbms_stats.gather_fixed_objects ('FIXED_STATS');
To copy the statistics from the temporary statistics table to the data dictionary use:
EXECUTE dbms_stats.gather_fixed_objects (NULL);
JMD Not tested by me.
Only gather fixed object statistics after the database has been running a representative workload
See Metalink Note

25. DBMS_STATS METHOD_OPT Parameter
Specifies histogram collection policy
Can be specified for:
GATHER_DATABASE_STATS,
GATHER_DICTIONARY_STATS,
GATHER_SCHEMA_STATS
GATHER_TABLE_STATS
Default is FOR ALL COLUMNS SIZE AUTO
Uses data from COL_USAGE$ table

26. DBMS_STATS METHOD_OPT Parameter
Syntax is:
FOR ALL [ INDEXED | HIDDEN ] COLUMNS [ size_clause ]
FOR COLUMNS [ [ size_clause ] column|attribute [size_clause] [, column|attribute [size_clause]..]
size_clause is:
SIZE { integer | REPEAT | AUTO | SKEWONLY }
where:
integer - number of histogram buckets (1..254)
REPEAT - only collect histograms for columns that already have histograms
AUTO - determine which columns need histograms automatically
SKEWONLY - determine which columns need histograms based on data distribution

27. DBMS_STATS Column Usage Monitoring
Column usage is recorded in SYS.COL_USAGE$
Column Name
Data Type
OBJ#
NUMBER
INTCOL#
EQUALITY_PREDS
EQUIJOIN_PREDS
NONEQUIJOIN_PREDS
RANGE_PREDS
LIKE_PREDS
NULL_PREDS
TIMESTAMP
DATE
COL_USAGE$ is
Updated when statements are parsed
Reset when statistics are gathered for table

28. DBMS_STATS Histograms Summary
Do not collect histograms if not necessary
Expensive to collect
Check accuracy of histograms
Watch for columns with high proportion of NULL values
Watch for highly skewed columns
Height-balanced histograms
Limited use if column is not highly skewed
Object oriented designs rarely work with histograms
Using histograms introduces bind variable peeking issues

29. DBMS_STATS Locking Statistics
Statistics can be locked for schemas, tables, and partitions
LOCK_SCHEMA_STATS / UNLOCK_SCHEMA_STATS
LOCK_TABLE_STATS / UNLOCK_TABLE_STATS
LOCK_PARTITION_STATS / UNLOCK_PARTITION_STATS
dbms_stats.lock_table_stats ( ownname => 'USER1', tabname => 'T1', stattype => 'ALL' );
Possible values for STATTYPE are NULL, DATA, CACHE and ALL
By default GATHER procedures will not overwrite locked statistics
Specify FORCE => TRUE to overwrite
Statistics locking reported in STATTYPE_LOCKED column in
DBA_TAB_STATISTICS
DBA_IND_STATISTICS

30. DBMS_STATS Default Parameters
In Oracle 10.1 and above default parameters can be specified
System-wide defaults can be set for
Column Name
Factory Default
CASCADE
DBMS_STATS.AUTO_CASCADE
DEGREE
NULL
ESTIMATE_PERCENT
DBMS_STATS.AUTO_SAMPLE_SIZE
METHOD_OPT
FOR ALL COLUMNS SIZE AUTO
NO_INVALIDATE
DBMS_STATS.AUTO_INVALIDATE
GRANULARITY
AUTO
AUTOSTATS_TARGET
AUTOSTATS_TARGET can be
ALL collect statistics for all objects in the database
ORACLE collect statistics for all Oracle-owned objects
AUTO determine which objects need new statistics
Statistics default values will be used in GATHER, EXPORT and IMPORT functions. Note that CASCADE is only applicable for GATHER
Factory defaults in Oracle 10.2 are:
CASCADE - DBMS_STATS.AUTO_CASCADE
DEGREE - NULL
ESTIMATE_PERCENT - DBMS_STATS.AUTO_SAMPLE_SIZE
METHOD_OPT- FOR ALL COLUMNS SIZE AUTO
NO_INVALIDATE - DBMS_STATS.NO_INVALIDATE
GRANULARITY - AUTO
AUTOSTATS_TARGET - AUTO
When setting parameters
NULL resets parameter to factory default
'NULL' specifies a value of NULL
Parameters can be reset to factory settings using the RESET_PARAM_DEFAULTS procedure

31. DBMS_STATS Default Parameters
To set default parameters use SET_PARAM:
dbms_stats.set_param (pname => 'CASCADE',pval => TRUE);
Take care with NULL values
For example:
dbms_stats.set_param ('ESTIMATE_PERCENT','NULL');
Sets the default to COMPUTE statistics
dbms_stats.set_param ('ESTIMATE_PERCENT',NULL);
Restores factory default (DBMS_STATS.AUTO_SAMPLE_SIZE)
To check default parameters use GET_PARAM e.g.:
GET_PARAM is obsolete in Oracle use GET_PREFS instead
SET_PARAM is obsolete in Oracle use SET_GLOBAL_PREFS instead
RESET_PARAM_DEFAULTS is obsolete in Oracle 11. Use RESET_GLOBAL_PREF_DEFAULTS instead
SELECT dbms_stats.get_param (pname => 'CASCADE') FROM dual;
To restore all factory default parameters use:
dbms_stats.reset_param_defaults;

32. ANALYZE versus DBMS_STATS

33. ANALYZE versus DBMS_STATS Differences
ANALYZE updates the following columns in DBA_TAB_STATISTICS
EMPTY_BLOCKS
AVG_SPACE
DBMS_STATS sets these columns to 0
Tables
AVG_ROW_LEN differs - e.g.:
Indexes
No obvious differences between ANALYZE and DBMS_STATS
Columns
AVG_COL_LEN differs - e.g.:
ANALYZE 43
DBMS_STATS 39
ANALYZE 4
DBMS_STATS 5

34. ANALYZE versus DBMS_STATS Differences
ANALYZE <table> gathers statistics for related indexes
Prior to Oracle 10.1 DBMS_STATS requires CASCADE => TRUE
For empty indexes
ANALYZE sets BLEVEL to 0
DBMS_STATS sets BLEVEL > 0

35. ANALYZE versus DBMS_STATS Summary
Use ANALYZE to
Collect index statistics without updating data dictionary
Identify candidates for index coalesce/rebuild
Identify candidates for index compression
Identify tables containing excessive chained rows
Use DBMS_STATS
Gather statistics on tables / indexes
Do not mix ANALYZE / DBMS_STATS

36. System Statistics

37. System Statistics Introduction
System statistics were introduced in Oracle 9.0.1
Subroutines are:
GATHER_SYSTEM_STATS
DELETE_SYSTEM_STATS
GET_SYSTEM_STATS
SET_SYSTEM_STATS
EXPORT_SYSTEM_STATS
IMPORT_SYSTEM_STATS
RESTORE_SYSTEM_STATS
System statistics are stored in SYS.AUX_STATS$

38. System Statistics Workload versus No Workload Statistics
Oracle 10.1 and above supports:
noworkload statistics - default values supplied during database creation
workload statistics - collected from representative workload
Workload statistics include:
CPUSPEED - CPU speed
SREADTIM - Single block read time in milliseconds
MREADTIM - Multi block read time in milliseconds
MBRC - Multi block read count
MAXTHR - Maximum I/O system throughput (parallel execution only)
SLAVETHR - Average slave I/O throughput (parallel execution only)
No workload statistics include:
CPUSPEEDNW - CPU speed
IOSEEKTIM - IO Seek Time
IOTFRSPEED - IO Transfer Speed
In Oracle 10.2 the optimizer uses the value of MBRC instead of db_file_multiblock_read_count to compute costs for full table scans and index fast full scans.
Oracle 9.0 includes CPUSPEED, SREADTIM, MREADTIM and MBRC.
MAXTHR and SLAVETHR were added in Oracle 9.2 to set a lower limit for full table scans
CPUSPEEDNW, IOSEEKTIM and IOTFRSPEED were added in Oracle 10.1
Values for CPUSPEEDNW, IOSEEKTIM and IOTFRSPEED can be collected using:
DBMS_STAT.GATHER_SYSTEM_STATS (gathering_mode =>NOWORKLOAD);

39. System Statistics Example
Create a statistics table using:
dbms_stats.create_stat_table ('SYS','OLTP_STATS');
Gather system statistics for a typical period using:
dbms_stats.gather_system_stats ( gathering_mode => 'INTERVAL', interval => 60, seconds stattab => OLTP_STATS', statid => 'OLTP' );
Import system statistics into AUX_STATS$ using:
In order to collect system statistics JOB_QUEUE_PROCESSES must be set to 1 or more:
ALTER SYSTEM SET job_queue_processes = 1;
dbms_stats.import_system_stats ( stattab => OLTP_STATS', statid => 'OLTP', statown => 'SYS' );

40. System Statistics Summary
Enable system statistics for single instance databases
Usually improve execution plans
Consider carefully before enabling system statistics in RAC databases
System statistics are database-specific
Watch for asymmetric nodes
Hardware differences
Service configuration
System statistics are:
Difficult to monitor
Very difficult to update / remove
If exporting object statistics to another system for testing:
Remember to export system statistics

41. Automatic Statistics Collection

42. Automatic Statistics Collection Introduction
Oracle 10.1 and above
Statistics collected during Maintenance Window
Monday - Friday 22:00 to 06:00
Saturday / Sunday All day
Note that weekend window effectively starts at 06:00 on Saturday morning
Scheduler job
GATHER_STATS_JOB
Scheduler job class
AUTO_TASKS_JOB_CLASS
Scheduler windows
WEEKNIGHT_WINDOW
WEEKEND_WINDOW
Scheduler window group
MAINTENANCE_WINDOW_GROUP

43. Statistics History

44. Statistics History Introduction
In Oracle 10.1 and above, existing statistics are stored in the data dictionary when new statistics are collected
Statistics can be restored using:
RESTORE_DATABASE_STATS
RESTORE_DICTIONARY_STATS
RESTORE_FIXED_OBJECTS_STATS
RESTORE_SCHEMA_STATS
RESTORE_SYSTEM_STATS
RESTORE_TABLE_STATS
Statistics history for tables only is reported in DBA_TAB_STATS_HISTORY
SELECT stats_update_time FROM dba_tab_stats_history WHERE owner = 'USER1' AND table_name = 'T1';
12-FEB PM +00:00

45. Statistics History Optimizer Statistics Operations
Statistics gathering operations are reported in DBA_OPTSTAT_OPERATIONS
SELECT operation, target, start_time, end_time FROM dba_optstat_operations ORDER BY start_time;
gather_database_stats(auto) 07-FEB FEB gather_database_stats(auto) 09-FEB FEB gather_database_stats(auto) 10-FEB FEB
DBA_OPTSTAT_OPERATIONS includes:
gather_database_stats(auto)
gather_schema_stats
DBA_OPTSTAT_OPERATIONS does not include:
gather_table_stats
gather_index_stats

46. Statistics History Data Dictionary Tables
Historic statistics are stored in tables created by
$ORACLE_HOME/rdbms/admin/catost.sql
Tables created are:
WRI$_OPTSTAT_TAB_HISTORY
WRI$_OPTSTAT_IND_HISTORY
WRI$_OPTSTAT_HISTHEAD_HISTORY
WRI$_OPTSTAT_HISTGRM_HISTORY
WRI$_OPTSTAT_AUX_HISTORY
WRI$_OPTSTAT_OPR
OPTSTAT_HIST_CONTROL$

47. Statistics History Retention Period
To check statistics history retention period use:
SELECT dbms_stats.get_stats_history_retention FROM dual;
Default is 31 days
To check earliest historic statistics use:
SELECT dbms_stats.get_stats_history_availability FROM dual;
12-JAN PM +00:00
To set statistics history retention period to 90 days:
dbms_stats.alter_stats_history_retention ( retention => 90 );

48. Statistics History Summary
Statistics history rows contain previous values for optimizer statistics
Statistics history does not include current value
SAVTIME column is time row was written
ANALYZETIME column is time statistics were analyzed
SAVTIME != ANALYZETIME
ANALYZE does not update statistics history
[UN]LOCK_TABLE_STATS do update statistics history

49. Manual Statistics

50. Setting Table Statistics Introduction
Table statistics can be set manually using SET_TABLE_STATS
Values can be specified for:
NUMROWS - number of rows
NUMBLKS - number of blocks
AVGRLEN - average row length

51. Setting Table Statistics Example (1 of 4)
DECLARE l_numrows NUMBER; l_numblks NUMBER; l_avgrlen NUMBER; l_flags NUMBER;
l_total_blocks NUMBER; l_total_bytes NUMBER; l_unused_blocks NUMBER; l_unused_bytes NUMBER; l_last_used_extent_file_id NUMBER; l_last_used_extent_block_id NUMBER; l_last_used_block NUMBER;

52. Setting Table Statistics Example (2 of 4)
BEGIN dbms_stats.get_table_stats ( ownname => 'GP', tabname => 'CAR', numrows => l_numrows, numblks => l_numblks, avgrlen => l_avgrlen, );
l_numrows := 0; l_numblks := 0;
SELECT COUNT(*) INTO l_numrows FROM gp.car;

53. Setting Table Statistics Example (3 of 4)
dbms_space.unused_space ( segment_owner => 'GP', segment_name => 'CAR', segment_type => 'TABLE', total_blocks => l_total_blocks, total_bytes => l_total_bytes, unused_blocks => l_unused_blocks, unused_bytes => l_unused_bytes, last_used_extent_file_id => l_last_used_extent_file_id, last_used_extent_block_id => l_last_used_extent_block_id, last_used_block => l_last_used_block );
l_numblks := l_total_blocks;

54. Setting Table Statistics Example (4 of 4)
dbms_stats.set_table_stats ( ownname => 'GP', tabname => 'CAR', numrows => l_numrows, numblks => l_numblks, avgrlen => l_avgrlen ); END;

55. Setting Index Statistics Introduction
Index statistics can be set manually using SET_INDEX_STATS
Values can be specified for:
NUMROWS - number of rows
NUMBLKS - number of blocks
NUMDIST - number of distinct values
AVGLBLK - average leaf blocks per key
AVGDBLK - average data blocks per key
CLSTFCT - clustering factor
INDLEVEL - index level (height)
Use ANALYZE INDEX VALIDATE STRUCTURE to determine values

56. Setting Column Statistics Introduction
Column statistics can be set manually using SET_COLUMN_STATS
Values can be specified for:
DISTCNT - number of distinct values
DENSITY - 1 / (number of distinct values)
NULLCNT - number of NULL values
Low and high values
Histograms
Note that DISTCNT usage differs for columns with histograms

57. Setting Column Statistics Data Types
Requires additional data types declared in DBMS_STATS package
See $ORACLE_HOME/rdbms/admin/dbmsstat.sql
TYPE numarray IS VARRAY(256) OF NUMBER;
TYPE chararray IS VARRAY(256) OF VARCHAR2(4000);
TYPE statrec IS RECORD ( EPC NUMBER, MINVAL RAW(2000), MAXVAL RAW(2000), BKVALS NUMARRAY, NOVALS NUMARRAY, CHVALS CHARARRAY, EAVS NUMBER )

58. Setting Column Statistics Example (1 of 3)
PROCEDURE copy_col_stats
(p_owner VARCHAR2,p_table_name VARCHAR2) IS l_row DBA_TAB_COLUMNS%ROWTYPE; l_statrec dbms_stats.statrec; l_numvals dbms_stats.numarray := dbms_stats.numarray(); l_charvals dbms_stats.chararray := dbms_stats.chararray(); l_datevals dbms_stats.datearray := dbms_stats.datearray();
CURSOR c1 RETURN DBA_TAB_COLUMNS%ROWTYPE IS SELECT * FROM dba_tab_columns WHERE owner = p_owner AND table_name = p_table_name;
BEGIN l_numvals.extend(2); l_charvals.extend(2); l_datevals.extend(2);
OPEN c1; LOOP FETCH c1 INTO l_row; EXIT WHEN c1%NOTFOUND;

59. Setting Column Statistics Example (2 of 3)
IF l_row.num_buckets IS NOT NULL THEN l_statrec.epc := 2; l_statrec.bkvals := NULL; l_numvals(1) := NULL; l_numvals(2) := NULL; l_charvals(1) := NULL; l_charvals(2) := NULL; l_datevals(1) := NULL; l_datevals(2) := NULL;
IF l_row.column_name = 'COL1' THEN l_numvals(1) := get_min_col1 (p_owner,p_table_name); l_numvals(2) := get_max_col2 (p_owner,p_table_name); DBMS_STATS.PREPARE_COLUMN_VALUES (l_statrec,l_numvals); ELSIF l_row.column_name = 'COL2' THEN l_datevals(1) := TO_DATE (v_target_date,'YYYYMMDD'); l_datevals(2) := TO_DATE (v_target_date,'YYYYMMDD'); DBMS_STATS.PREPARE_COLUMN_VALUES (l_statrec,l_datevals); ELSIF l_row.column_name = 'COL3' THEN l_charvals(1) := get_min_col3 (p_owner,p_table_name); l_charvals(2) := get_max_col3 (p_owner,p_table_name); DBMS_STATS.PREPARE_COLUMN_VALUES (l_statrec,l_charvals); END IF;

60. Setting Column Statistics Example (3 of 3)
Setting minimum and maximum values (without histograms)
DBMS_STATS.SET_COLUMN_STATS ( ownname => p_owner, tabname => p_table_name, colname => l_row.column_name, distcnt => l_row.num_distinct, density => l_row.density, nullcnt => l_row.num_nulls, srec => l_statrec, avgclen => l_row.avg_col_len ); END IF; END LOOP; CLOSE c1; END;

61. Setting Column Statistics - Histograms Example (1 of 2)
DECLARE l_statrec dbms_stats.statrec; l_charvals dbms_stats.chararray := dbms_stats.chararray (); l_bkvals dbms_stats.numarray := dbms_stats.numarray (); BEGIN l_charvals.extend (11); l_bkvals.extend (11);
l_charvals(1) := 'MSCH'; l_bkvals(1) := 91; l_charvals(2) := 'APRO'; l_bkvals(2) := 51; l_charvals(3) := 'ASEN'; l_bkvals(3) := 41; l_charvals(4) := 'NMAN'; l_bkvals(4) := 31; l_charvals(5) := 'JSTE'; l_bkvals(5) := 27; l_charvals(6) := 'NLAU'; l_bkvals(6) := 25; l_charvals(7) := 'JCLA'; l_bkvals(7) := 25; l_charvals(8) := 'NPIQ'; l_bkvals(8) := 23; l_charvals(9) := 'FALO'; l_bkvals(9) := 22; l_charvals(10) := 'DHIL'; l_bkvals(10) := 22; l_charvals(11) := 'MHAK'; l_bkvals(11) := 20;

62. Setting Column Statistics - Histograms Example (2 of 2)
l_statrec.epc := 11; l_statrec.bkvals := l_bkvals; l_statrec.eavs := 0;
DBMS_STATS.PREPARE_COLUMN_VALUES (l_statrec,l_charvals);
DBMS_STATS.SET_COLUMN_STATS ( ownname => 'GP', tabname => 'CAR', colname => 'DRIVER_KEY', distcnt => 11, density => , / 476 rows nullcnt => 0, srec => l_statrec, avgclen => 4 ); END; /

63. Partition Statistics

64. Partition Statistics Introduction
Partition statistics are reported by:
DBA_TABLES
DBA_TAB_PARTITIONS DBA_TAB_STATISTICS
DBA_TAB_SUBPARTITIONS (Oracle 10.1 and above)
Indexes
DBA_INDEXES
DBA_IND_PARTITIONS DBA_IND_STATISTICS
DBA_IND_SUBPARTITIONS (Oracle 10.1 and above)
Columns
DBA_TAB_COL_STATISTICS
DBA_PART_COL_STATISTICS
DBA_SUBPART_COL_STATISTICS
Histograms
DBA_TAB_HISTOGRAMS
DBA_PART_HISTOGRAMS
DBA_SUBPART_HISTOGRAMS

65. Partition Statistics Example (1 of 12)
Create a range partitioned table containing data for last four seasons
CREATE TABLE car3 PARTITION BY RANGE (season_key) ( PARTITION p2005 VALUES LESS THAN ('2006'), PARTITION p2006 VALUES LESS THAN ('2007'), PARTITION p2007 VALUES LESS THAN ('2008'), PARTITION p2008 VALUES LESS THAN ('2009') ) AS SELECT * FROM car WHERE season_key >= '2005';
CREATE INDEX car3_i1 ON car3(season_key,race_key,position) LOCAL;
dbms_stats.gather_table_stats ( ownname => 'GP', tabname => 'CAR3', estimate_percent => NULL, cascade => TRUE );

66. Partition Statistics Example (2 of 12)
Table Statistics
SELECT num_rows,blocks,avg_row_len FROM dba_tables WHERE owner = 'GP' AND table_name = 'CAR3';
NUM_ROWS
BLOCKS
AVG_ROW_LEN
1518 24 37
SELECT partition_name,num_rows,blocks,avg_row_len FROM dba_tab_partitions WHERE table_owner = 'GP' AND table_name = 'CAR3';
PARTITION_NAME
NUM_ROWS
BLOCKS
AVG_ROW_LEN
P2005
380 6 36
P2006
396 38
P2007
374 37
P2008
368

67. Partition Statistics Example (3 of 12)
Index Statistics
SELECT blevel, leaf_blocks, distinct_keys, clustering_factor, num_rows FROM dba_indexes WHERE owner = 'GP' AND index_name = 'CAR3_I1';
BLEVEL
LEAF_BLOCKS
DIST KEYS
CLUFAC
NUM_ROWS 1 8
1518 15
SELECT partition_name, blevel, leaf_blocks, distinct_keys, clustering_factor, num_rows FROM dba_ind_partitions WHERE index_owner = 'GP' AND index_name = 'CAR3_I1';
PARTITION_NAME
BLEVEL
LEAF_BLOCKS
DIST KEYS
CLUFAC
NUM_ROWS
P2005 1 2
380 3
P2006
396
P2007
374 5
P2008
368 4
Note in the above examples, AVG_LEAF_BLOCKS_PER_KEY and AVG_DATA_BLOCKS_PER_KEY were always 1so have been omitted to improve readability.

68. Partition Statistics Example (4 of 12)
Add a new partition for 2009 season
ALTER TABLE car3 ADD PARTITION p2009 VALUES LESS THAN ('2010');
Gather statistics again
dbms_stats.gather_table_stats ( ownname => 'GP', tabname => 'CAR3', estimate_percent => NULL, cascade => TRUE );

69. Partition Statistics Example (5 of 12)
Table Statistics
SELECT num_rows,blocks,avg_row_len FROM dba_tables WHERE owner = 'GP' AND table_name = 'CAR3';
NUM_ROWS
BLOCKS
AVG_ROW_LEN
1518 24 37
SELECT partition_name,num_rows,blocks,avg_row_len FROM dba_tab_partitions WHERE table_owner = 'GP' AND table_name = 'CAR3';
PARTITION_NAME
NUM_ROWS
BLOCKS
AVG_ROW_LEN
P2005
380 6 36
P2006
396 38
P2007
374 37
P2008
368
P2009

70. Partition Statistics Example (6 of 12)
Index Statistics
SELECT blevel, leaf_blocks, distinct_keys, clustering_factor, num_rows FROM dba_indexes WHERE owner = 'GP' AND index_name = 'CAR3_I1';
BLEVEL
LEAF_BLOCKS
DIST KEYS
CLUFAC
NUM_ROWS 1 8
1518 15
SELECT partition_name, blevel, leaf_blocks, distinct_keys, clustering_factor, num_rows FROM dba_ind_partitions WHERE index_owner = 'GP' AND index_name = 'CAR3_I1';
PARTITION_NAME
BLEVEL
LEAF_BLOCKS
DIST KEYS
CLUFAC
NUM_ROWS
P2005 1 2
380 3
P2006
396
P2007
374 5
P2008
368 4
P2009
Note in the above examples, AVG_LEAF_BLOCKS_PER_KEY and AVG_DATA_BLOCKS_PER_KEY were always 1so have been omitted to improve readability.

71. Partition Statistics Example (7 of 12)
Copy table statistics from 2008 to 2009 partitions
dbms_stats.copy_table_stats ( ownname => 'GP', tabname => 'CAR3', srcpartname => 'P2008', dstpartname => 'P2009' );

72. Partition Statistics Example (8 of 12)
Table Statistics
SELECT num_rows,blocks,avg_row_len FROM dba_tables WHERE owner = 'GP' AND table_name = 'CAR3';
NUM_ROWS
BLOCKS
AVG_ROW_LEN
1518 24 37
SELECT partition_name,num_rows,blocks,avg_row_len FROM dba_tab_partitions WHERE table_owner = 'GP' AND table_name = 'CAR3';
PARTITION_NAME
NUM_ROWS
BLOCKS
AVG_ROW_LEN
P2005
380 6 36
P2006
396 38
P2007
374 37
P2008
368
P2009

73. Partition Statistics Example (9 of 12)
Index Statistics
SELECT blevel, leaf_blocks, distinct_keys, clustering_factor, num_rows FROM dba_indexes WHERE owner = 'GP' AND index_name = 'CAR3_I1';
BLEVEL
LEAF_BLOCKS
DIST KEYS
CLUFAC
NUM_ROWS 1 8
1518 15
SELECT partition_name, blevel, leaf_blocks, distinct_keys, clustering_factor, num_rows FROM dba_ind_partitions WHERE index_owner = 'GP' AND index_name = 'CAR3_I1';
PARTITION_NAME
BLEVEL
LEAF_BLOCKS
DIST KEYS
CLUFAC
NUM_ROWS
P2005 1 2
380 3
P2006
396
P2007
374 5
P2008
368 4
P2009
Note in the above examples, AVG_LEAF_BLOCKS_PER_KEY and AVG_DATA_BLOCKS_PER_KEY were always 1so have been omitted to improve readability.

74. Partition Statistics Example (10 of 12)
Copy rows from 2008 to For example:
INSERT INTO car3 SELECT '2009', race_key, driver_key, team_key, engine_key, position, laps_completed, classification_key, notes, driver_points, team_points FROM gp.car3 WHERE season_key = '2008';
Statistics are unchanged

75. Partition Statistics Example (11 of 12)
Execution plans for statement against 2008 and 2009 partitions:
SELECT SUM(team_points) FROM gp.car3 WHERE season_key = '2008';
0 SELECT STATEMENT SORT AGGREGATE PARTITION RANGE (SINGLE) TABLE ACCESS (FULL) OF 'CAR3'
SELECT SUM(team_points) FROM gp.car3 WHERE season_key = '2009';
0 SELECT STATEMENT SORT AGGREGATE PARTITION RANGE (SINGLE) TABLE ACCESS (BY INDEX ROWID) OF 'CAR3' INDEX (RANGE SCAN) OF 'CAR3_I1'
Plans are different even though statistics and data are theoretically identical

76. Partition Statistics Example (12 of 12)
In Oracle column values are not updated by COPY_TABLE_STATS
SELECT partition_name,low_value,high_value FROM dba_part_col_statistics WHERE owner = 'GP' AND table_name = 'CAR3' AND column_name = 'SEASON_KEY';
PARTITION_NAME
LOW_VALUE
HIGH_VALUE
P2005
0x (2005)
P2006
0x (2006)
P2007
0x (2007)
P2008
0x (2008)
P2009
Caused by bug only affects
Fixed in patch
includes fixes for COPY_TABLE_STATS and APPROX_GLOBAL

77. Partition Statistics Summary
Range-partitioning
Only collect statistics for partitions undergoing change
Specify partition names and GRANULARITY parameter to restrict partitions that are analyzed
Consider setting statistics manually for new partitions
COPY_STATS has limited functionality
Watch for changing high values
Use DBMS_STATS NO_INVALIDATE option
ANALYZE invalidates all cursors referencing table being analyzed
Can result in hard-parse rates approaching 100%

78. Oracle 11g Enhancements

79. Statistics Preferences

80. Oracle 11g Enhancements Statistics Preferences
In Oracle 10g preferences are:
set using SET_PARAM
reported by GET_PARAM
stored in SYS.OPTSTAT_HIST_CONTROL$
In Oracle 11.1 and above preferences are:
set using:
SET_TABLE_PREFS
SET_SCHEMA_PREFS
SET_DATABASE_PREFS
SET_GLOBAL_PREFS
reported by
GET_PREFS
DBA_TAB_STAT_PREFS
stored in SYS.OPTSTAT_USER_PREFS$
In Oracle 11.1 and above global preferences can be reset using
RESET_GLOBAL_PREF_DEFAULTS
By default SET_DATABASE_PREFS set statistics preferences for all tables in the database EXCEPT for tables owned by Oracle.
Tables owned by Oracle can be included by specifying ADD_SYS => TRUE
SET_SCHEMA_PREFS sets statistics preferences for all tables in the specified schema.
Specifying a NULL value in SET_SCHEMA_PREFS restores all tables in the schema to the default value. Rows in OPTSTAT_USER_PREFS$ are updated, but not deleted.

81. Oracle 11g Enhancements Statistics Preferences
Allow automatic statistics collection to be customized for individual objects
For example heavily skewed data distributions
Can be set at table, schema, database and global level
In Oracle 10g preferences can be set for:
CASCADE
DEGREE
ESTIMATE_PERCENT
METHOD_OPT
NO_INVALIDATE
GRANULARITY
In Oracle 11g preferences can also be set for:
PUBLISH - if TRUE publish statistics; if FALSE store as pending
STALE_PERCENT - threshold level at which statistics considered stale
INCREMENTAL - if TRUE collect incremental global partition statistics

82. Oracle 11g Enhancements Statistics Preferences
Delete preferences using:
DELETE_TABLE_PREFS
DELETE_SCHEMA_PREFS
DELETE_DATABASE_PREFS
Export and import preferences using:
EXPORT_TABLE_PREFS / IMPORT_TABLE_PREFS
EXPORT_SCHEMA_PREFS / IMPORT_SCHEMA_PREFS
EXPORT_DATABASE_PREFS / IMPORT_DATABASE_PREFS

83. Pending Statistics

84. Oracle 11g Enhancements Pending Statistics
In Oracle 11.1 and above statistics can be
Published - current statistics used by optimizer
Pending - private statistics not yet published
In Oracle 11.1 statistics for a set of objects can be collected as an atomic transaction
Published at same time
Avoids inconsistencies
PUBLISH mode can be set at the following levels
Global
Database
Schema
Table

85. Oracle 11g Enhancements Pending Statistics
To defer publication of all statistics collected by USER1 use:
dbms_stats.set_schema_prefs ('USER1','PUBLISH','FALSE');
To make pending statistics temporarily available to the optimizer use:
ALTER SESSION optimizer_use_pending_statistics = TRUE;
To make pending statistics permanently available to the optimizer use:
dbms_stats.publish_pending_statistics ( ownname => 'USER1', tabname => NULL );
The default value for OPTIMIZER_USE_PENDING_STATISTICS is FALSE.
To make all pending statistics permanently available to the optimizer use: dbms_stats.publish_pending_statistics ( ownname => NULL, tabname => NULL );
Statistics can also be published for individual tables. For example:
dbms_stats.publish_pending_statistics ( ownname => 'USER1', tabname => 'T1' );
Both the NO_INVALIDATE and FORCE options can be specified for PUBLISH_PENDING_STATISTICS.
Pending statistics can be deleted using DELETE_PENDING_STATS
Pending statistics can be exported using EXPORT_PENDING_STATS. There is no corresponding import procedure
Statistics can be published at database, schema or table level
To delete pending statistics use DELETE_PENDING_STATS
To export pending statistics use EXPORT_PENDING_STATS
There is no corresponding import procedure

86. Extended Statistics

87. Oracle 11g Enhancements Extended Statistics
Extended statistics attempt to reflect true selectivity of data
There are two types:
multi-column statistics
expression statistics
Extended statistics use the following procedures:
CREATE_EXTENDED_STATS
DROP_EXTENDED_STATS
SHOW_EXTENDED_STATS_NAME

88. Oracle 11g Enhancements Multi-Column Statistics
In Oracle 11g the following statistics can be gathered on multiple columns in a table (column groups):
Number of distinct values
Density
Number of nulls
Frequency histograms
Multicolumn statistics
Appear to work for frequency histograms
<= 254 combinations of values
Do not appear to work for height-based histograms
> 254 combinations of values

89. Oracle 11g Enhancements Multi-Column Statistics
SELECT COUNT(*) FROM gp.car WHERE team_key = 'FER' AND engine_key = 'FER';
COUNT(*) Id
Operation
Name
Rows
Bytes
Cost (%CPU)
Time
SELECT STATEMENT
35 (100) 1
SORT AGGREGATE 13 2
TABLE ACCESS FULL
CAR
137
1781
35 (0)
00:00:01
Incorrect Cardinality

90. Oracle 11g Enhancements Multi-Column Statistics
DECLARE l_extension_name VARCHAR2(30); BEGIN l_extension_name := dbms_stats.create_extended_stats ( ownname => 'GP', tabname => 'CAR', extension => '(team_key,engine_key)' ); END;
BEGIN dbms_stats.gather_table_stats ( ownname => 'GP', tabname => 'CAR', estimate_percent => NULL, method_opt => 'FOR ALL COLUMNS SIZE 254 '|| 'FOR COLUMNS (TEAM_KEY,ENGINE_KEY) SIZE 254' ); END;

91. Oracle 11g Enhancements Multi-Column Statistics
SELECT COUNT(*) FROM gp.car WHERE team_key = 'FER' AND engine_key = 'FER';
COUNT(*) Id
Operation
Name
Rows
Bytes
Cost (%CPU)
Time
SELECT STATEMENT
35 (100) 1
SORT AGGREGATE 13 2
TABLE ACCESS FULL
CAR
1410
18330
35 (0)
00:00:01
Correct Cardinality

92. Oracle 11g Enhancements Multi-Column Statistics
SELECT extension_name,extension FROM dba_stat_extensions WHERE owner = 'GP' AND table_name = 'CAR';
Extension Name
Extension
SYS_STUWIHETSRHT#5P210Z$AO1ON9
("TEAM_KEY","ENGINE_KEY")

93. Oracle 11g Enhancements Multi-Column Statistics
SELECT c.intcol#,c.col#,c.name FROM sys.col$ c, sys.obj$ o, sys.user$ u WHERE c.obj# = o.obj# AND o.name = 'CAR' AND o.owner# = u.user# AND u.name = 'GP';
INTCOL#
COL#
NAME 1
SEASON_KEY 2
RACE_KEY 3
DRIVER_KEY 4
TEAM_KEY 5
ENGINE_KEY 6
POSITION 7
LAPS_COMPLETED 8
CLASSIFICATION_KEY 9
NOTES 10
SYS_STUWIHETSRHT#5P210Z$AO1ON9
New Virtual Column in Table for Multi-Column Statistics

94. Oracle 11g Enhancements Expression Statistics
CREATE OR REPLACE FUNCTION points (season_key VARCHAR2,race_key NUMBER,position NUMBER) RETURN NUMBER DETERMINISTIC IS l_result NUMBER; BEGIN l_result := CASE position WHEN 1 THEN 10 WHEN 2 THEN 8 WHEN 3 THEN 6 WHEN 4 THEN 5 WHEN 5 THEN 4 WHEN 6 THEN 3 WHEN 7 THEN 2 WHEN 8 THEN 1 ELSE 0 END; RETURN l_result; END;
Note: The real algorithm is MUCH more complicated for various reasons including:
changes to number of points awarded
disqualifications, penalties etc
differences between drivers and team championship points systems

95. Oracle 11g Enhancements Expression Statistics
SELECT COUNT(*) FROM gp.car WHERE POINTS (season_key,race_key,position) = 10;
COUNT(*) 709 Id
Operation
Name
Rows
Bytes
Cost (%CPU)
Time
SELECT STATEMENT
38 (100) 1
SORT AGGREGATE 13 2
TABLE ACCESS FULL
CAR
177
4248
38 (0)
00:00:01
Incorrect Cardinality

96. Oracle 11g Enhancements Expression Statistics
DECLARE l_extension_name VARCHAR2(30); BEGIN l_extension_name := dbms_stats.create_extended_stats ( ownname => 'GP', tabname => 'CAR', extension => '(points(season_key,race_key,position))' ); END;
BEGIN dbms_stats.gather_table_stats ( ownname => 'GP', tabname => 'CAR', estimate_percent => NULL, method_opt => 'FOR ALL COLUMNS SIZE 254 '|| 'FOR COLUMNS (points(season_key,race_key,position)) SIZE 254' ); END;

97. Oracle 11g Enhancements Expression Statistics
SELECT COUNT(*) FROM gp.car WHERE POINTS (season_key,race_key,position) = 10;
COUNT(*) 709 Id
Operation
Name
Rows
Bytes
Cost (%CPU)
Time
SELECT STATEMENT
38 (100) 1
SORT AGGREGATE 13 2
TABLE ACCESS FULL
CAR
709
19143
38 (0)
00:00:01
Correct Cardinality

98. Oracle 11g Enhancements Incremental Statistics
For partitioned tables statistics can be collected:
For sub-partitions
For partitions
Globally
Global statistics should reflect underlying partitioned statistics
Prior to Oracle 11.1 calculation of global statistics required full table scan of each partition in table
For many applications using range partitioning only the most recent partition is subject to change
Older partitions contain historical data

99. Oracle 11g Enhancements Incremental Statistics
For example:
CREATE TABLE car4 PARTITION BY RANGE (season_key) ( PARTITION p2006 VALUES LESS THAN ('2005'), PARTITION p2007 VALUES LESS THAN ('2006'), PARTITION p2008 VALUES LESS THAN ('2007'), PARTITION p2009 VALUES LESS THAN ('2008') ) AS SELECT * FROM car WHERE season_key >= '2005';
CREATE INDEX i_car4_1 ON carp(season_key,race_key,position) LOCAL;
INSERT INTO car4 SELECT * FROM car WHERE season_key BETWEEN 2006 AND 2009;
Create table with partitions for four years data
Insert data

100. Oracle 11g Enhancements Incremental Statistics
Gather statistics
DBMS_STATS.GATHER_TABLE_STATS ( ownname => 'GP', tabname => 'CAR4' );
Requires full table scan for each partition
2006
Full Table Scan
2007
Full Table Scan
2008
Full Table Scan
2009
Full Table Scan

101. Oracle 11g Enhancements Incremental Statistics
Update data in one partition:
UPDATE car4 SET team_points = driver_points WHERE season_key = '2009';
Gather table statistics again:
DBMS_STATS.GATHER_TABLE_STATS ( ownname => 'GP', tabname => 'CAR4' );
Still requires full table scan for each partition
2006
Full Table Scan
2007
Full Table Scan
2008
Full Table Scan
2009
Full Table Scan

102. Oracle 11g Enhancements Incremental Statistics
In Oracle 11.1 and above statistics can be gathered incrementally for partitioned tables
To gather incremental statistics on a specific table
INCREMENTAL and PUBLISH preferences for table must be TRUE
ESTIMATE_PERCENT must be AUTO_SAMPLE_SIZE
GRANULARITY must be AUTO
For each partition a synopsis is created
Contains data about distinct values for each column in partition
Stored in
SYS.WRI$_OPTSTAT_SYNOPSIS_HEAD$
SYS.WRI$_OPTSTAT_SYNOPSIS$
If a partition has not been modified synopsis can be used to calculate global statistics
Synopsis must be generated for all partitions first time statistics are gathered after incremental statistics are enabled

103. Oracle 11g Enhancements Incremental Statistics
Set INCREMENTAL preference to TRUE for table:
BEGIN DBMS_STATS.SET_TABLE_PREFS ( ownname => 'GP', tabname => 'CAR4', pname => 'INCREMENTAL', pvalue => 'TRUE' ); END; /
Gather table statistics again to generate synopsis for each partition
DBMS_STATS.GATHER_TABLE_STATS ( ownname => 'GP', tabname => 'CAR4' );
All partitions will be scanned first time to create synopsis

104. Oracle 11g Enhancements Incremental Statistics
Update data in one partition:
UPDATE car4 SET team_points = driver_points WHERE season_key = '2009';
Gather table statistics again:
DBMS_STATS.GATHER_TABLE_STATS ( ownname => 'GP', tabname => 'CARP' );
Uses synopsis for unmodified partitions
Requires full table scan for modified partition
2006
Synopsis
2007
Synopsis
2008
Synopsis
2009
Full Table Scan

105. Thanks to the following for corrections:
Greg Rahn
Tony Hasler