GreenPlum 大数据平台--运维(一)

.最后分析或真空或创建表或等...
   Select * from pg_stat_operations where schemaname='SCHEMA NAME '
 and actionname in ('ANALYZE','VACUUM') order by statime;

.长时间查询空闲：
  Select * from pg_stat_activity order by query_start,backend_start;

gpdb=# Select * from pg_stat_activity order by query_start,backend_start;
 datid |  datname  | procpid | sess_id | usesysid | usename |
    current_query                            | waiting |          query_start
   |         backend_start         |  client_addr  | client_port | application_name
|          xact_start           | waiting_reason | rsgid | rsgname | rsgqueueduratio
n
-------+-----------+---------+---------+----------+---------+-----------------------
---------------------------------------------+---------+----------------------------
---+-------------------------------+---------------+-------------+------------------
+-------------------------------+----------------+-------+---------+----------------
--
  | gpperfmon |    |     |     | gpmon   | <IDLE>
                                             | f       | -- ::40.079557-
 | -- ::25.082823- | 192.168.0.221 |        | gpcc
|                               |                |      | unknown |
  | gpperfmon |     |      |     | gpmon   | <IDLE>
                                             | f       | -- ::45.883945-
 | -- ::55.080215- | 192.168.0.221 |        | gpcc
|                               |                |      | unknown |
  | gpdb      |     |    |        | gpadmin | Select * from pg_stat_
activity order by query_start,backend_start; | f       | -- ::47.667488-
 | -- ::20.171974- |               |          - | psql
| -- ::47.667488- |                |      | unknown |
( rows)

.如何在数据库中找到最大的表？
   SELECT relname, relpages FROM pg_class ORDER BY relpages DESC;

gpdb=#  SELECT relname, relpages FROM pg_class ORDER BY relpages DESC;
                            relname                             | relpages
----------------------------------------------------------------+----------
 test_1                                                         |     1672
 test_index_1                                                   |     1672
 test99                                                         |     1000
 gp_disk_free                                                   |     1000
 __gp_log_segment_ext                                           |     1000
 t1                                                             |     1000
 __gp_localid                                                   |     1000
 __gp_masterid                                                  |     1000
 __gp_log_master_ext                                            |     1000
 test_index_1_idx                                               |       56
 pg_proc                                                        |       20
 pg_rewrite                                                     |       19
 pg_attribute                                                   |       14
 pg_depend                                                      |       14
 pg_depend_reference_index                                      |       13
 pg_depend_depender_index                                       |       13
 pg_proc_proname_args_nsp_index                                 |        9
 test66                                                         |        8
 pg_statistic                                                   |        6
 gp_persistent_relation_node                                    |        6
 pg_description                                                 |        6
 pg_attribute_relid_attnam_index                                |        6
 pg_attribute_relid_attnum_index                                |        5
 pg_description_o_c_o_index                                     |        5
 test1                                                          |        5
 pg_proc_oid_index                                              |        5
 test2                                                          |        4
 test110                                                        |        4
 pg_operator                                                    |        4
 gpcrondump_history                                             |        3
 pg_type                                                        |        3

.数据库中的前5个最大表
   SELECT relname, relpages FROM pg_class ORDER BY relpages DESC limit ; 

gpdb=# SELECT relname, relpages FROM pg_class ORDER BY relpages DESC limit 5;
       relname       | relpages
---------------------+----------
 test_index_1        |     1672
 test_1              |     1672
 __gp_localid        |     1000
 __gp_masterid       |     1000
 __gp_log_master_ext |     1000
(5 rows)

       relname– 关系/表的名称.
       relpages - 关系页面（页数，默认情况下页面为8kb）
       pg_class– 系统表，维护关系的细节
       limit  – 限制输出只显示5行。
.如何计算磁盘中的数据库大小？
        SELECT pg_database_size('Database Name' );
        SELECT pg_size_pretty(pg_database_size( 'Database Name' ));

gpdb=# SELECT pg_database_size('gpdb' );
 pg_database_size
------------------
        215354446
(1 row)
 
gpdb=# SELECT pg_database_size('postgres' );
 pg_database_size
------------------
        214830158
(1 row)
 
gpdb=# SELECT pg_size_pretty(pg_database_size( 'gpdb' ));
 pg_size_pretty
----------------
 205 MB
(1 row)
 
gpdb=# SELECT pg_size_pretty(pg_database_size( 'postgres' ));
 pg_size_pretty
----------------
 205 MB
(1 row)

.如何计算磁盘中的表大小？
        SELECT pg_size_pretty(pg_total_relation_size('public.test1'));

gpdb=# SELECT pg_size_pretty(pg_total_relation_size('public.test1'));
 pg_size_pretty
----------------
 160 kB
(1 row)

.如何查找表的大小（不包括索引）？
        SELECT pg_size_pretty(pg_relation_size('public.test1')); 

gpdb=# SELECT pg_size_pretty(pg_relation_size('public.test1'));
 pg_size_pretty
----------------
 160 kB
(1 row)

.如何生成一系列数字并将其插入表格中？
        INSERT INTO test2  (id) VALUES ( generate_series(,));  

gpdb=# INSERT INTO test3 (id) VALUES ( generate_series(1,1000));
INSERT 0 1000
gpdb=# SELECT * from test3 limit 3;
 id | name
----+------
  1 |
  9 |
 17 |
(3 rows)

.如何计算表中的总行数？
        select count(*) from  test1;

gpdb=# select count(*) from  test2;
 count
-------
  1006
(1 row)

.具有特定列值的行总数不为空。
       select count(id) from public.test1; 

gpdb=# select count(id) from public.test1;
 count
-------
     6
(1 row)

.如何获取表中列的最大值？ - 第一秒
       select max( col_name) from  table ;
       SELECT MIN(col name) from table_namewhere num > (select MIN(col
name) from table_name);
.如何获得表中列的第二个最小值？ - 第一个和第二个
       select min(col_name) from table;
       SELECT MIN(col name) from table_namewhere num > (select MIN(col
name) from table_name);
.如何查看GP中的基本可用数据类型。
       SELECT typname,typlen from pg_type where typtype='b';
typname – 数据类型的名称
typlen – 数据类型的长度

gpdb=# SELECT typname,typlen from pg_type where typtype='b';
       typname       | typlen
---------------------+--------
 bool                |      1
 bytea               |     -1
 char                |      1
 name                |     64
 int8                |      8
 int2                |      2
 int2vector          |     -1
 int4                |      4
 regproc             |      4
 text                |     -1
 oid                 |      4
 tid                 |      6
 xid                 |      4
 cid                 |      4
 oidvector           |     -1
 xml                 |     -1
 _xml                |     -1
 json                |     -1
 _json               |     -1
 complex             |     16
 _complex            |     -1
 smgr                |      2
 point               |     16
 lseg                |     32
 path                |     -1
 box                 |     32
 polygon             |     -1
 line                |     32
 _line               |     -1
 float4              |      4
 float8              |      8
 abstime             |      4
 reltime             |      4

.显示已关闭的segments。
      Select * from gp_segment_configuration where status='d';
.查找当前用户：
      SELECT SESSION_USER, CURRENT_USER; 

gpdb=#  SELECT SESSION_USER, CURRENT_USER;
 session_user | current_user
--------------+--------------
 gpadmin      | gpadmin
(1 row)

.检查活动会话（工作负载）：
     SELECT * FROM pg_stat_activity; 

gpdb=# SELECT * FROM pg_stat_activity;
 datid |  datname  | procpid | sess_id | usesysid | usename |          current_query
          | waiting |          query_start          |         backend_start
|  client_addr  | client_port | application_name |          xact_start           | w
aiting_reason | rsgid | rsgname | rsgqueueduration
-------+-----------+---------+---------+----------+---------+-----------------------
----------+---------+-------------------------------+-------------------------------
+---------------+-------------+------------------+-------------------------------+--
--------------+-------+---------+------------------
 16385 | gpperfmon |    7652 |     207 |    16558 | gpmon   | <IDLE>
          | f       | 2019-03-20 21:28:10.079528-04 | 2019-03-19 01:52:55.080215-04
| 192.168.0.221 |       45824 | gpcc             |                               |
              |     0 | unknown |
 16385 | gpperfmon |   31604 |    2822 |    16558 | gpmon   | <IDLE>
          | f       | 2019-03-20 21:28:25.079502-04 | 2019-03-19 05:45:25.082823-04
| 192.168.0.221 |       62596 | gpcc             |                               |
              |     0 | unknown |
 16384 | gpdb      |    6961 |   27890 |       10 | gpadmin | SELECT * FROM pg_stat_
activity; | f       | 2019-03-20 21:28:29.916239-04 | 2019-03-20 21:19:20.171974-04
|               |          -1 | psql             | 2019-03-20 21:28:29.916239-04 |
              |     0 | unknown |
(3 rows)

.正在队列中等待的查询
     SELECT * FROM gp_tookit.gp_resqueue_status; 
 
.查看数据库列表
      SELECT datname from pg_database;

gpdb=# SELECT datname from pg_database;
  datname
-----------
 template1
 template0
 postgres
 gpdb
 gpperfmon
 test2
(6 rows)

 

 

定义

动词carefully choose as being the best or most suitable.

形容词(of a group of people or things) carefully chosen from a larger number as being the best or most valuable.

同义词

动词choose; pick (out); single out; sort out; take; opt for; decide on; settle on; determine; nominate; appoint; elect

形容词choice; hand-picked; prime; first-rate; first-class; superior; finest; best; top-class; blue-ribbon; supreme; superb; excellent; A1; top-notch

示例

Punching in the code known only to a very select few, the doors opened with small hiss.