GreenPlum 大數據平臺--運維(一)

1.最後分析或真空或建立表或等...
   Select * from pg_stat_operations where schemaname='SCHEMA NAME '
 and actionname in ('ANALYZE','VACUUM') order by statime; 

2.長時間查詢空閒：
  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
-------+-----------+---------+---------+----------+---------+-----------------------
---------------------------------------------+---------+----------------------------
---+-------------------------------+---------------+-------------+------------------
+-------------------------------+----------------+-------+---------+----------------
--
 16385 | gpperfmon |   31604 |    2822 |    16558 | gpmon   | <IDLE>
                                             | f       | 2019-03-20 21:19:40.079557-
04 | 2019-03-19 05:45:25.082823-04 | 192.168.0.221 |       62596 | gpcc
|                               |                |     0 | unknown |
 16385 | gpperfmon |    7652 |     207 |    16558 | gpmon   | <IDLE>
                                             | f       | 2019-03-20 21:19:45.883945-
04 | 2019-03-19 01:52:55.080215-04 | 192.168.0.221 |       45824 | gpcc
|                               |                |     0 | unknown |
 16384 | gpdb      |    6961 |   27890 |       10 | gpadmin | Select * from pg_stat_
activity order by query_start,backend_start; | f       | 2019-03-20 21:19:47.667488-
04 | 2019-03-20 21:19:20.171974-04 |               |          -1 | psql
| 2019-03-20 21:19:47.667488-04 |                |     0 | unknown |
(3 rows)

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3.如何在數據庫中找到最大的表？
   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

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4.數據庫中的前5個最大表
   SELECT relname, relpages FROM pg_class ORDER BY relpages DESC limit 5; 

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)

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       relname– 關係/表的名稱. 
       relpages - 關係頁面（頁數，默認狀況下頁面爲8kb）
       pg_class– 系統表，維護關係的細節 
       limit 5 – 限制輸出只顯示5行。
5.如何計算磁盤中的數據庫大小？
        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)

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6.如何計算磁盤中的表大小？
        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)

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7.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)

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8.如何生成一系列數字並將其插入表格中？
        INSERT INTO test2  (id) VALUES ( generate_series(1,1000));  

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)

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9.如何計算表中的總行數？
        select count(*) from  test1;

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

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10.具備特定列值的行總數不爲空。
       select count(id) from public.test1; 

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

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11.如何獲取表中列的最大值？ - 第一秒
       select max( col_name) from  table ;
       SELECT MIN(col name) from table_namewhere num > (select MIN(col 
name) from table_name);
12.如何得到表中列的第二個最小值？ - 第一個和第二個
       select min(col_name) from table;
       SELECT MIN(col name) from table_namewhere num > (select MIN(col 
name) from table_name);
13.如何查看GP中的基本可用數據類型。
       SELECT typname,typlen from pg_type where typtype='b';
typname – 數據類型的名稱 
typlen – 數據類型的長度

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

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14.顯示已關閉的segments。
      Select * from gp_segment_configuration where status='d'; 
15.查找當前用戶：
      SELECT SESSION_USER, CURRENT_USER; 

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

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16.檢查活動會話（工做負載）：
     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)

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17.正在隊列中等待的查詢
     SELECT * FROM gp_tookit.gp_resqueue_status; 
   
18.查看數據庫列表
      SELECT datname from pg_database;

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

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select

[səˈlekt]

動詞 選擇; 選; 挑選; 點; 擇; 篩選; 選拔; 遴選; 挑; 選派; 擢; 挑揀; 拔; 遴; 銓; 掄; 芼; 諏; 摘; 挑定; 提選; 甄拔

形容詞 上等的; 選出的; 優良的

定義

動詞 carefully choose as being the best or most suitable.

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

同義詞

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

形容詞 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.