pg_squeeze
os: ubuntu 16.04
db: postgresql 10.6
pg_squeeze is an extension that removes unused space from a table and
optionally sorts tuples according to particular index (as if CLUSTER [2]
command was executed concurrently with regular reads / writes). In fact we try
to replace pg_repack [1] extension.
First, make sure that your table has either primary key or unique
constraint. This is necessary to process changes other transactions might do
while “pg_squeeze” is doing its work.
版本
# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.5 LTS
Release: 16.04
Codename: xenial
#
# su - postgres
$ psql -c "select version();"
version
-----------------------------------------------------------------------------------------------------------------
PostgreSQL 10.6 on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 5.4.0-6ubuntu1~16.04.11) 5.4.0 20160609, 64-bit
(1 row)
下载安装
# su - postgres
$ git clone https://github.com/cybertec-postgresql/pg_squeeze.git
$ cd pg_squeeze
$ git branch -a
$ git checkout VERSION3_1_15
- Set PG_CONFIG environment variable to point to pg_config command of your PostgreSQL installation.
$ cd ~/pg_squeeze
$ vi Makefile
PG_CONFIG=/usr/pgsql-10/bin/pg_config
- make
- sudo make install
$ make all
$ make install
/bin/mkdir -p '/usr/pgsql-10/lib'
/bin/mkdir -p '/usr/pgsql-10/share/extension'
/bin/mkdir -p '/usr/pgsql-10/share/extension'
/usr/bin/install -c -m 755 pg_squeeze.so '/usr/pgsql-10/lib/pg_squeeze.so'
/usr/bin/install -c -m 644 .//pg_squeeze.control '/usr/pgsql-10/share/extension/'
/usr/bin/install -c -m 644 .//pg_squeeze--1.0.sql '/usr/pgsql-10/share/extension/'
$ ls -l /usr/pgsql-10/lib/* |grep -i pg_squeeze;
-rwxr-xr-x 1 postgres postgres 298520 Apr 8 11:39 /usr/pgsql-10/lib/pg_squeeze.so
$ ls -l /usr/pgsql-10/share/extension/* |grep -i pg_squeeze;
-rw-r--r-- 1 postgres postgres 18391 Apr 8 11:39 /usr/pgsql-10/share/extension/pg_squeeze--1.0.sql
-rw-r--r-- 1 postgres postgres 184 Apr 8 11:39 /usr/pgsql-10/share/extension/pg_squeeze.control
- Apply the following settings to postgresql.conf:
wal_level = logical
max_replication_slots = 10 # … or add 1 to the current value.
shared_preload_libraries = ‘pg_squeeze’ # … or add the library to the existing ones.
postgres=# show wal_level;show max_replication_slots;show shared_preload_libraries;
wal_level
-----------
logical
(1 row)
max_replication_slots
-----------------------
10
(1 row)
shared_preload_libraries
-----------------------------------------------------------------
(0 row)
$ vi $PGDATA/postgresql.conf
wal_level = logical
max_replication_slots = 10 #
shared_preload_libraries = 'pg_squeeze'
- Start the PG cluster.
$ pg_ctl stop -m fast -D /data/pgsql-10/data
$ pg_ctl start -D /data/pgsql-10/data
- As a superuser, run
postgres=# CREATE EXTENSION pg_squeeze;
CREATE EXTENSION
postgres=# \dx
List of installed extensions
Name | Version | Schema | Description
--------------------+---------+------------+-----------------------------------------------------------------
pg_squeeze | 1.0 | squeeze | A tool to remove unused space from a relation.
plpgsql | 1.0 | pg_catalog | PL/pgSQL procedural language
(2 rows)
postgres=# \dn
List of schemas
Name | Owner
------------+----------
public | postgres
squeeze | postgres
(2 rows)
使用
准备基础数据:创建 public.tmp_t0,插入 100w 条数据
postgres=# create table tmp_t0( c0 int8 primary key,c1 varchar(100),c2 varchar(100));
CREATE TABLE
postgres=#
postgres=# insert into tmp_t0 select id,md5(id::varchar),md5(md5(id::varchar)) from generate_series(1,1000000) as id;
INSERT 0 1000000
postgres=#
postgres=# \dt+ tmp_t0
List of relations
Schema | Name | Type | Owner | Size | Description
--------+--------+-------+----------+--------+-------------
public | tmp_t0 | table | postgres | 104 MB |
(1 row)
插入定期清理数据: 定期清理public.tmp_t0表，1分钟一次，
postgres=# insert into squeeze.tables (tabschema,tabname,first_check,free_space_extra,task_interval)
values('public','tmp_t0',now(),20,interval '1 minutes');
表示空闲空间超过 20%就会对表进行重建.
手动启动pg_squeeze的进程需要调用
postgres=# SELECT squeeze.start_worker();
不需要时关闭pg_squeeze的进程调用
postgres=# SELECT squeeze.stop_worker();
查看当前表的膨胀情况及此时表的大小
postgres=# select * from squeeze.tables_internal;
table_id | class_id | class_id_toast | free_space | last_task_created | last_task_finished
----------+----------+----------------+-------------------+-------------------+--------------------
1 | 57797 | 0 | 0.784470774697771 | |
(1 row)
postgres=# \dt+ tmp_t0
List of relations
Schema | Name | Type | Owner | Size | Description
--------+--------+-------+----------+--------+-------------
public | tmp_t0 | table | postgres | 103 MB |
(1 row)
删除 50w 数据
postgres=# delete from tmp_t0 where c0 <=500000;
DELETE 500000
稍等一会,查看当前表的膨胀情况 及 public.tmp_t0 的大小
postgres=# select * from squeeze.tables_internal;
table_id | class_id | class_id_toast | free_space | last_task_created | last_task_finished
----------+----------+----------------+------------+-------------------------------+------------------------------
11 | | | | 2019-04-09 08:34:31.563214+08 | 2019-04-09 08:34:31.65691+08
(1 row)
Time: 0.528 ms
postgres=# \dt+ tmp_t0
List of relations
Schema | Name | Type | Owner | Size | Description
--------+--------+-------+----------+-------+-------------
public | tmp_t0 | table | postgres | 52 MB |
(1 row)
参考:
https://github.com/cybertec-postgresql/pg_squeeze
https://www.cybertec-postgresql.com/en/products/pg_squeeze/