PostgreSQL 14新插件pg_surgery

Posted 2021-08-23 PostgreSQLChina

作者：金涛

PostgreSQL新增extension pg_surgery, 提供了两个函数：

• heap_force_freeze - 强制要冻结tuple
• heap_force_kill - 强制删除tuple

jintao@jintao-ThinkPad-L490:~/personal/code/postgresql-master$ psql 
psql (14devel)
Type 'help' for help.
mydb=# select version();
                                                 version                                                 
---------------------------------------------------------------------------------------------------------
 PostgreSQL 14devel on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0, 64-bit
(1 row)
mydb=# create extension pg_surgery ;
CREATE EXTENSION
mydb=# 
mydb=# \\dx+ pg_surgery
     Objects in extension 'pg_surgery'
             Object description             
--------------------------------------------
 function heap_force_freeze(regclass,tid[])
 function heap_force_kill(regclass,tid[])
(2 rows)
mydb=# create table test_surgery(id int);
CREATE TABLE
mydb=# 
mydb=# insert into test_surgery select generate_series(1,5);
INSERT 0 5
mydb=# 
mydb=# select xmin, ctid, id from test_surgery ;
 xmin | ctid  | id 
------+-------+----
  836 | (0,1) |  1
  836 | (0,2) |  2
  836 | (0,3) |  3
  836 | (0,4) |  4
  836 | (0,5) |  5
(5 rows)
mydb=# select heap_force_freeze('test_surgery'::regclass, array[ '(0,1)' ]::tid[]);     /*freeze单个ctid*/
 heap_force_freeze 
-------------------
(1 row)
mydb=# select xmin, ctid, id from test_surgery ;
 xmin | ctid  | id 
------+-------+----
    2 | (0,1) |  1
  836 | (0,2) |  2
  836 | (0,3) |  3
  836 | (0,4) |  4
  836 | (0,5) |  5
(5 rows)
mydb=# select heap_force_freeze('test_surgery'::regclass, array[ '(0,2)', '(0,5)' ]::tid[]);     /*freeze单个ctid*/
 heap_force_freeze 
-------------------
(1 row)
mydb=# select xmin, ctid, id from test_surgery ;
 xmin | ctid  | id 
------+-------+----
    2 | (0,1) |  1
    2 | (0,2) |  2
  836 | (0,3) |  3
  836 | (0,4) |  4
    2 | (0,5) |  5
(5 rows)
mydb=# 
mydb=# select heap_force_kill('test_surgery'::regclass, array[ '(0,1)' ]::tid[]);                  /*删除单个ctid tuple */
 heap_force_kill 
-----------------
(1 row)
mydb=# select xmin, ctid, id from test_surgery ;
 xmin | ctid  | id 
------+-------+----
    2 | (0,2) |  2
  836 | (0,3) |  3
  836 | (0,4) |  4
    2 | (0,5) |  5
(4 rows)
mydb=# select heap_force_kill('test_surgery'::regclass, array[ '(0,3)', '(0,5)' ]::tid[]);            /*删除多个ctid tuple*/
 heap_force_kill 
-----------------
(1 row)
mydb=# select xmin, ctid, id from test_surgery ;
 xmin | ctid  | id 
------+-------+----
    2 | (0,2) |  2
  836 | (0,4) |  4
(2 rows)
mydb=#

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