About stats collected

pg_class.relpages pg_class.reltuples只是近似值，和实际数据会有点误差；

新建空表，首次insert对自动收集和更新统计信息，影响的表pg_class\pg_stats；

对于insert操作:

analyze会更新表pg_class\pg_stats，而vacuum或者acuum full只会更新pg_class，并不会更新任何统计信息pg_stats；

对于update\delete操作:

analyze会更新表pg_class\pg_stats，而vacuum或者acuum full只会更新pg_class，并不会更新任何统计信息pg_stats；

但是vacuum full对于索引对象的pg_class.relpages貌似存在bug，只有再次analyze或者vacuum才会正确更新pg_class;

gp_autostats_mode可以配置参数有：

NONE

ON_NO_STATS

ON_CHANGE

默认是ON_NO_STATS

gp_autostats_on_change_threshold参数配置阀值，与gp_autostats_mode配合使用，该值为临界值下限，比如80000，那么在超过80000也即等于80001的时候才会生效。

 

详细测试如下：
[gpadmin@wx60 ~]$ psql gtlions
psql (8.2.15)
Type "help" for help.
 
gtlions=# \timing on
Timing is on.
gtlions=# select version();
                                                                       version                                                                        
------------------------------------------------------------------------------------------------------------------------------------------------------
 PostgreSQL 8.2.15 (Greenplum Database 4.2.7.2 build 1) on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.4.2 compiled on Feb 25 2014 18:05:04
(1 row)
 
Time: 2.020 ms
gtlions=# \pset x
Expanded display is on.
gtlions=# select * from pg_settings where name ~ 'gp_autostats';
-[ RECORD 1 ]---------------------------------------------------------------------------------------------------------------------------------
name       | gp_autostats_mode
setting    | ON_NO_STATS
unit       | 
category   | Developer Options
short_desc | Sets the autostats mode.
extra_desc | Valid values are NONE, ON_CHANGE, ON_NO_STATS. ON_CHANGE requires setting gp_autostats_on_change_threshold.
context    | user
vartype    | string
source     | configuration file
min_val    | 
max_val    | 
-[ RECORD 2 ]---------------------------------------------------------------------------------------------------------------------------------
name       | gp_autostats_on_change_threshold
setting    | 2147483647
unit       | 
category   | Developer Options
short_desc | Threshold for number of tuples added to table by CTAS or Insert-to to trigger autostats in on_change mode. See gp_autostats_mode.
extra_desc | 
context    | user
vartype    | integer
source     | configuration file
min_val    | 0
max_val    | 2147483647
 
Time: 4.464 ms
gtlions=# \q
[gpadmin@wx60 ~]$ gpconfig -c gp_autostats_on_change_threshold -v 80000
20141017:16:45:27:008114 gpconfig:wx60:gpadmin-[INFO]:-completed successfully
[gpadmin@wx60 ~]$ gpstop -u
20141017:16:45:32:008229 gpstop:wx60:gpadmin-[INFO]:-Starting gpstop with args: -u
20141017:16:45:32:008229 gpstop:wx60:gpadmin-[INFO]:-Gathering information and validating the environment...
20141017:16:45:32:008229 gpstop:wx60:gpadmin-[INFO]:-Obtaining Greenplum Master catalog information
20141017:16:45:32:008229 gpstop:wx60:gpadmin-[INFO]:-Obtaining Segment details from master...
20141017:16:45:33:008229 gpstop:wx60:gpadmin-[INFO]:-Greenplum Version: 'postgres (Greenplum Database) 4.2.7.2 build 1'
20141017:16:45:33:008229 gpstop:wx60:gpadmin-[INFO]:-Signalling all postmaster processes to reload
. 
[gpadmin@wx60 ~]$ psql gtlions
psql (8.2.15)
Type "help" for help.
 
gtlions=# \pset x
Expanded display is on.
gtlions=# select * from pg_settings where name ~ 'gp_autostats';
-[ RECORD 1 ]---------------------------------------------------------------------------------------------------------------------------------
name       | gp_autostats_mode
setting    | ON_NO_STATS
unit       | 
category   | Developer Options
short_desc | Sets the autostats mode.
extra_desc | Valid values are NONE, ON_CHANGE, ON_NO_STATS. ON_CHANGE requires setting gp_autostats_on_change_threshold.
context    | user
vartype    | string
source     | configuration file
min_val    | 
max_val    | 
-[ RECORD 2 ]---------------------------------------------------------------------------------------------------------------------------------
name       | gp_autostats_on_change_threshold
setting    | 80000
unit       | 
category   | Developer Options
short_desc | Threshold for number of tuples added to table by CTAS or Insert-to to trigger autostats in on_change mode. See gp_autostats_mode.
extra_desc | 
context    | user
vartype    | integer
source     | configuration file
min_val    | 0
max_val    | 2147483647
 
gtlions=# drop table if exists test;
DROP TABLE
gtlions=# create table test ( id int, name varchar(200),age int);
NOTICE:  Table doesn't have 'DISTRIBUTED BY' clause -- Using column named 'id' as the Greenplum Database data distribution key for this table.
HINT:  The 'DISTRIBUTED BY' clause determines the distribution of data. Make sure column(s) chosen are the optimal data distribution key to minimize skew.
CREATE TABLE
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
-[ RECORD 1 ]------
relname     | test
relfilenode | 35843
relpages    | 0
reltuples   | 0
relhasindex | f
relnatts    | 3
 
gtlions=# \pset x
Expanded display is off.
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35843 |        0 |         0 | f           |        3
(1 row)
 
gtlions=# select * from pg_stats where tablename='test';  
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs | histogram_bounds | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+------------------+-------------
(0 rows)
 
gtlions=# select * from gp_toolkit.gp_stats_missing 
  
gtlions=# select * from gp_toolkit.gp_stats_missing where smitable='test';
 smischema | smitable | smisize | smicols | smirecs 
-----------+----------+---------+---------+---------
 public    | test     | f       |       3 |       0
(1 row)
 
gtlions=# insert into  test select generate_series(1,80000),generate_series(1,80000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 20000;
INSERT 0 20000
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35843 |       32 |     20000 | f           |        3
(1 row)
 
gtlions=# select * from pg_stats where tablename='test';                  
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs |                                                        
       histogram_bounds                                                               | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+--------------------------------------------------------
--------------------------------------------------------------------------------------+-------------
 public     | test      | id      |         0 |         4 |         -1 |                  |                   | {1,801,1601,2401,3201,4001,4801,5601,6401,7201,8001,880
1,9601,10401,11201,12001,12801,13601,14401,15201,16001,16801,17601,18401,19201,20000} |            
 public     | test      | name    |         0 |        13 |         -1 |                  |                   |                                                        
                                                                                      |            
 public     | test      | age     |         0 |         4 |          1 | {39}             | {1}               | {39}                                                   
                                                                                      |            
(3 rows)
 
gtlions=# select * from gp_toolkit.gp_stats_missing where smitable='test';
 smischema | smitable | smisize | smicols | smirecs 
-----------+----------+---------+---------+---------
(0 rows)
 
gtlions=# \q
[gpadmin@wx60 ~]$ gpconfig -c gp_autostats_mode -v NONE                   
20141017:16:50:17:008707 gpconfig:wx60:gpadmin-[INFO]:-completed successfully
[gpadmin@wx60 ~]$ gpstop -u
20141017:16:50:20:008822 gpstop:wx60:gpadmin-[INFO]:-Starting gpstop with args: -u
20141017:16:50:20:008822 gpstop:wx60:gpadmin-[INFO]:-Gathering information and validating the environment...
20141017:16:50:20:008822 gpstop:wx60:gpadmin-[INFO]:-Obtaining Greenplum Master catalog information
20141017:16:50:20:008822 gpstop:wx60:gpadmin-[INFO]:-Obtaining Segment details from master...
20141017:16:50:20:008822 gpstop:wx60:gpadmin-[INFO]:-Greenplum Version: 'postgres (Greenplum Database) 4.2.7.2 build 1'
20141017:16:50:20:008822 gpstop:wx60:gpadmin-[INFO]:-Signalling all postmaster processes to reload
. 
[gpadmin@wx60 ~]$ psql gtlions
psql (8.2.15)
Type "help" for help.
 
gtlions=# \pset x
Expanded display is on.
gtlions=# select * from pg_settings where name ~ 'gp_autostats';
-[ RECORD 1 ]---------------------------------------------------------------------------------------------------------------------------------
name       | gp_autostats_mode
setting    | NONE
unit       | 
category   | Developer Options
short_desc | Sets the autostats mode.
extra_desc | Valid values are NONE, ON_CHANGE, ON_NO_STATS. ON_CHANGE requires setting gp_autostats_on_change_threshold.
context    | user
vartype    | string
source     | configuration file
min_val    | 
max_val    | 
-[ RECORD 2 ]---------------------------------------------------------------------------------------------------------------------------------
name       | gp_autostats_on_change_threshold
setting    | 80000
unit       | 
category   | Developer Options
short_desc | Threshold for number of tuples added to table by CTAS or Insert-to to trigger autostats in on_change mode. See gp_autostats_mode.
extra_desc | 
context    | user
vartype    | integer
source     | configuration file
min_val    | 0
max_val    | 2147483647
 
gtlions=# drop table test;
DROP TABLE
gtlions=# \pset x
Expanded display is off.
gtlions=# create table test ( id int, name varchar(200),age int);
NOTICE:  Table doesn't have 'DISTRIBUTED BY' clause -- Using column named 'id' as the Greenplum Database data distribution key for this table.
HINT:  The 'DISTRIBUTED BY' clause determines the distribution of data. Make sure column(s) chosen are the optimal data distribution key to minimize skew.
CREATE TABLE
gtlions=# insert into  test select generate_series(1,80000),generate_series(1,80000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 20000;
INSERT 0 20000
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35866 |        0 |         0 | f           |        3
(1 row)
 
gtlions=# select * from pg_stats where tablename='test';                  
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs | histogram_bounds | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+------------------+-------------
(0 rows)
 
gtlions=# select * from gp_toolkit.gp_stats_missing where smitable='test';
 smischema | smitable | smisize | smicols | smirecs 
-----------+----------+---------+---------+---------
 public    | test     | f       |       3 |       0
(1 row)
 
gtlions=# analyze test;
ANALYZE
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35866 |       32 |     20000 | f           |        3
(1 row)
 
gtlions=# select * from pg_stats where tablename='test';                  
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs |                                                        
       histogram_bounds                                                               | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+--------------------------------------------------------
--------------------------------------------------------------------------------------+-------------
 public     | test      | id      |         0 |         4 |         -1 |                  |                   | {1,801,1601,2401,3201,4001,4801,5601,6401,7201,8001,880
1,9601,10401,11201,12001,12801,13601,14401,15201,16001,16801,17601,18401,19201,20000} |            
 public     | test      | name    |         0 |        13 |         -1 |                  |                   |                                                        
                                                                                      |            
 public     | test      | age     |         0 |         4 |          1 | {32}             | {1}               | {32}                                                   
                                                                                      |            
(3 rows)
 
gtlions=# select * from gp_toolkit.gp_stats_missing where smitable='test';
 smischema | smitable | smisize | smicols | smirecs 
-----------+----------+---------+---------+---------
(0 rows)
 
gtlions=# \q
[gpadmin@wx60 ~]$ gpconfig -c gp_autostats_mode -v ON_CHANGE
20141017:16:52:15:009211 gpconfig:wx60:gpadmin-[INFO]:-completed successfully
[gpadmin@wx60 ~]$ gpstop -u
20141017:16:52:18:009326 gpstop:wx60:gpadmin-[INFO]:-Starting gpstop with args: -u
20141017:16:52:18:009326 gpstop:wx60:gpadmin-[INFO]:-Gathering information and validating the environment...
20141017:16:52:18:009326 gpstop:wx60:gpadmin-[INFO]:-Obtaining Greenplum Master catalog information
20141017:16:52:18:009326 gpstop:wx60:gpadmin-[INFO]:-Obtaining Segment details from master...
20141017:16:52:18:009326 gpstop:wx60:gpadmin-[INFO]:-Greenplum Version: 'postgres (Greenplum Database) 4.2.7.2 build 1'
20141017:16:52:18:009326 gpstop:wx60:gpadmin-[INFO]:-Signalling all postmaster processes to reload
. 
[gpadmin@wx60 ~]$ psql gtlions
psql (8.2.15)
Type "help" for help.
 
gtlions=# \pset x
Expanded display is on.
gtlions=# select * from pg_settings where name ~ 'gp_autostats';
-[ RECORD 1 ]---------------------------------------------------------------------------------------------------------------------------------
name       | gp_autostats_mode
setting    | ON_CHANGE
unit       | 
category   | Developer Options
short_desc | Sets the autostats mode.
extra_desc | Valid values are NONE, ON_CHANGE, ON_NO_STATS. ON_CHANGE requires setting gp_autostats_on_change_threshold.
context    | user
vartype    | string
source     | configuration file
min_val    | 
max_val    | 
-[ RECORD 2 ]---------------------------------------------------------------------------------------------------------------------------------
name       | gp_autostats_on_change_threshold
setting    | 80000
unit       | 
category   | Developer Options
short_desc | Threshold for number of tuples added to table by CTAS or Insert-to to trigger autostats in on_change mode. See gp_autostats_mode.
extra_desc | 
context    | user
vartype    | integer
source     | configuration file
min_val    | 0
max_val    | 2147483647
 
gtlions=# \pset x
Expanded display is off.
gtlions=# drop table test;
DROP TABLE
gtlions=# create table test ( id int, name varchar(200),age int);
NOTICE:  Table doesn't have 'DISTRIBUTED BY' clause -- Using column named 'id' as the Greenplum Database data distribution key for this table.
HINT:  The 'DISTRIBUTED BY' clause determines the distribution of data. Make sure column(s) chosen are the optimal data distribution key to minimize skew.
CREATE TABLE
gtlions=# insert into  test select generate_series(1,80000),generate_series(1,80000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 20000;
INSERT 0 20000
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35889 |        0 |         0 | f           |        3
(1 row)
 
gtlions=# select * from pg_stats where tablename='test';                  
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs | histogram_bounds | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+------------------+-------------
(0 rows)
 
gtlions=# select * from gp_toolkit.gp_stats_missing where smitable='test';
 smischema | smitable | smisize | smicols | smirecs 
-----------+----------+---------+---------+---------
 public    | test     | f       |       3 |       0
(1 row)
 
gtlions=# insert into  test select generate_series(1,80000),generate_series(1,80000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 20000;
INSERT 0 20000
gtlions=# select * from pg_stats where tablename='test';
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs | histogram_bounds | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+------------------+-------------
(0 rows)
 
gtlions=# insert into  test select generate_series(1,80000),generate_series(1,80000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 20000;
INSERT 0 20000
gtlions=# select * from pg_stats where tablename='test';
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs | histogram_bounds | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+------------------+-------------
(0 rows)
 
gtlions=# select count(*) from test;
 count 
-------
 60000
(1 row)
 
gtlions=# insert into  test select generate_series(1,80000),generate_series(1,80000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 19999;
INSERT 0 19999
gtlions=# select count(*) from test;
 count 
-------
 79999
(1 row)
 
gtlions=# select count(*) from test;
 count 
-------
 79999
(1 row)
 
gtlions=# select * from pg_stats where tablename='test';
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs | histogram_bounds | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+------------------+-------------
(0 rows)
 
gtlions=# insert into  test select generate_series(1,80000),generate_series(1,80000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 1;
INSERT 0 1
gtlions=# select count(*) from test;
 count 
-------
 80000
(1 row)
 
gtlions=# select * from pg_stats where tablename='test';
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs | histogram_bounds | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+------------------+-------------
(0 rows)
 
gtlions=# insert into  test select generate_series(1,80000),generate_series(1,80000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 1;
INSERT 0 1
gtlions=# select count(*) from test;
 count 
-------
 80001
(1 row)
 
gtlions=# select * from pg_stats where tablename='test';
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs | histogram_bounds | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+------------------+-------------
(0 rows)
 
gtlions=# select * from pg_stats where tablename='test';
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs | histogram_bounds | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+------------------+-------------
(0 rows)
 
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35889 |        0 |         0 | f           |        3
(1 row)
 
gtlions=# insert into  test select generate_series(1,80000),generate_series(1,80000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 10000;
INSERT 0 10000
gtlions=# select count(*) from test;
 count 
-------
 90001
(1 row)
 
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35889 |        0 |         0 | f           |        3
(1 row)
 
gtlions=# select * from pg_stats where tablename='test';
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs | histogram_bounds | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+------------------+-------------
(0 rows)
 
gtlions=# insert into  test select generate_series(1,80000),generate_series(1,80000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 10000;
INSERT 0 10000
gtlions=# insert into  test select generate_series(1,80000),generate_series(1,80000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 10000;
INSERT 0 10000
gtlions=# insert into  test select generate_series(1,80000),generate_series(1,80000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 10000;
INSERT 0 10000
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35889 |        0 |         0 | f           |        3
(1 row)
 
gtlions=# select * from pg_stats where tablename='test';
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs | histogram_bounds | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+------------------+-------------
(0 rows)
 
gtlions=# insert into  test select generate_series(1,80000),generate_series(1,80000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 80000; 
INSERT 0 80000
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35889 |        0 |         0 | f           |        3
(1 row)
 
gtlions=# select * from pg_stats where tablename='test';
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs | histogram_bounds | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+------------------+-------------
(0 rows)
 
gtlions=# insert into  test select generate_series(1,80000),generate_series(1,80000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 80000;
INSERT 0 80000
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35889 |        0 |         0 | f           |        3
(1 row)
 
gtlions=# select * from pg_stats where tablename='test';
 schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals | most_common_freqs | histogram_bounds | correlation 
------------+-----------+---------+-----------+-----------+------------+------------------+-------------------+------------------+-------------
(0 rows)
 
gtlions=# insert into  test select generate_series(1,90000),generate_series(1,90000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 80001;
INSERT 0 80001
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35889 |      574 |    361046 | f           |        3
(1 row)
 
gtlions=# select * from pg_stats where tablename='test';
 schemaname | tablename | attname | null_frac | avg_width | n_distinct |                                                                                               
                                                              most_common_vals                                                                                         
                                                                    |                                                                                                  
                           most_common_freqs                                                                                                                           
   |                                                                     histogram_bounds                                                                     | correla
tion 
------------+-----------+---------+-----------+-----------+------------+-----------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------+--------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------
---+----------------------------------------------------------------------------------------------------------------------------------------------------------+--------
-----
 public     | test      | id      |         0 |         4 |  -0.174002 | {1241,7638,3257,2327,1485,9298,2465,6481,6316,2423,1618,1694,5551,3915,6216,15550,11567,3513,3
088,18221,1274,7119,1266,5539,5937}                                                                                                                                    
                                                                    | {0.00020724,0.0001727,0.0001727,0.0001727,0.0001727,0.0001727,0.0001727,0.0001727,0.0001727,0.000
1727,0.0001727,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.0001381
6} | {2,1361,2586,3868,5172,6432,7736,9052,10533,12609,14761,16810,18829,22174,27068,31789,36502,41340,46046,50856,55455,60203,65163,69993,74722,79997,79998} |        
    
 public     | test      | name    |         0 |        13 |  -0.174002 | {1241-aaa-bbb,1485-aaa-bbb,6316-aaa-bbb,9298-aaa-bbb,1618-aaa-bbb,7638-aaa-bbb,2327-aaa-bbb,64
81-aaa-bbb,3257-aaa-bbb,2465-aaa-bbb,2423-aaa-bbb,1266-aaa-bbb,8043-aaa-bbb,4306-aaa-bbb,7255-aaa-bbb,19759-aaa-bbb,6083-aaa-bbb,4287-aaa-bbb,14424-aaa-bbb,4623-aaa-bb
b,8661-aaa-bbb,4980-aaa-bbb,5161-aaa-bbb,8999-aaa-bbb,8694-aaa-bbb} | {0.00020724,0.0001727,0.0001727,0.0001727,0.0001727,0.0001727,0.0001727,0.0001727,0.0001727,0.000
1727,0.0001727,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.00013816,0.0001381
6} |                                                                                                                                                          |        
    
 public     | test      | age     |         0 |         4 |         11 | {19,10,74,32,68,35,75,5,65,93,46}                                                             
                                                                                                                                                                       
                                                                    | {0.224026,0.221021,0.217878,0.0573708,0.0556784,0.0546422,0.0538823,0.0300497,0.0290826,0.0285991
,0.0277701}                                                                                                                                                            
   | {5,10,19,32,35,46,65,68,74,75,93}                                                                                                                        |        
    
(3 rows)
 
gtlions=# truncate tabel test;
ERROR:  syntax error at or near "test"
LINE 1: truncate tabel test;
                       ^
gtlions=# truncate table test;  
TRUNCATE TABLE
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35936 |        0 |         0 | f           |        3
(1 row)
 
gtlions=# insert into  test select generate_series(1,90000),generate_series(1,90000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 90000;
INSERT 0 90000
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35936 |      144 |     90576 | f           |        3
(1 row)
 
gtlions=# update test set name='a' where id<=79999;
UPDATE 79999
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35936 |      144 |     90576 | f           |        3
(1 row)
 
gtlions=# update test set name='a' where id<=79999;
UPDATE 79999
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35936 |      144 |     90576 | f           |        3
(1 row)
 
gtlions=# update test set name='a' where id<=80000;
UPDATE 80000
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35936 |      144 |     90576 | f           |        3
(1 row)
 
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35936 |      144 |     90576 | f           |        3
(1 row)
 
gtlions=# update test set name='a' where id<=80001;
UPDATE 80001
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35936 |      574 |    101174 | f           |        3
(1 row)
 
gtlions=# truncate table test;
TRUNCATE TABLE
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35995 |        0 |         0 | f           |        3
(1 row)
 
gtlions=# insert into  test select generate_series(1,90000),generate_series(1,90000)||'-aaa-bbb',round(random()::numeric,2)*100 limit 90000;
INSERT 0 90000
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35995 |      144 |     90576 | f           |        3
(1 row)
 
gtlions=# update test set name='a' where id<80000;
UPDATE 79999
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35995 |      144 |     90576 | f           |        3
(1 row)
 
gtlions=# update test set name='a' where id<80001;
UPDATE 80000
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35995 |      144 |     90576 | f           |        3
(1 row)
 
gtlions=# update test set name='a' where id<80002;
UPDATE 80001
gtlions=# select relname,relfilenode,relpages,reltuples,relhasindex,relnatts from pg_class where relname in ('test') order by relname;
 relname | relfilenode | relpages | reltuples | relhasindex | relnatts 
---------+-------------+----------+-----------+-------------+----------
 test    |       35995 |      466 |     66052 | f           |        3
(1 row)

 

 

-EOF-