PostgreSQL DBA(163) - Extension(pg_cron)

本文简单介绍了PostgreSQL的插件：pg_cron。该插件可在PG中实现类似crontab的功能。

安装
编译安装

[pg12@localhost pg_cron]$git clone https://github.com/citusdata/pg_cron.git[pg12@localhost pg_cron]$cd pg_cron[pg12@localhost pg_cron]$ makegcc -std=gnu99 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -g -O0 -DOPTIMIZER_DEBUG -g3 -gdwarf-2 -fPIC -std=c99 -Wall -Wextra -Werror -Wno-unused-parameter -Wno-implicit-fallthrough -Iinclude -I/appdb/pg12/pg12.1/include -I. -I./ -I/appdb/pg12/pg12.1/include/postgresql/server -I/appdb/pg12/pg12.1/include/postgresql/internal  -D_GNU_SOURCE -I/usr/include/libxml2   -c -o src/pg_cron.o src/pg_cron.c -MMD -MP -MF .deps/pg_cron.Pogcc -std=gnu99 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -g -O0 -DOPTIMIZER_DEBUG -g3 -gdwarf-2 -fPIC -std=c99 -Wall -Wextra -Werror -Wno-unused-parameter -Wno-implicit-fallthrough -Iinclude -I/appdb/pg12/pg12.1/include -I. -I./ -I/appdb/pg12/pg12.1/include/postgresql/server -I/appdb/pg12/pg12.1/include/postgresql/internal  -D_GNU_SOURCE -I/usr/include/libxml2   -c -o src/job_metadata.o src/job_metadata.c -MMD -MP -MF .deps/job_metadata.Pogcc -std=gnu99 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -g -O0 -DOPTIMIZER_DEBUG -g3 -gdwarf-2 -fPIC -std=c99 -Wall -Wextra -Werror -Wno-unused-parameter -Wno-implicit-fallthrough -Iinclude -I/appdb/pg12/pg12.1/include -I. -I./ -I/appdb/pg12/pg12.1/include/postgresql/server -I/appdb/pg12/pg12.1/include/postgresql/internal  -D_GNU_SOURCE -I/usr/include/libxml2   -c -o src/misc.o src/misc.c -MMD -MP -MF .deps/misc.Pogcc -std=gnu99 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -g -O0 -DOPTIMIZER_DEBUG -g3 -gdwarf-2 -fPIC -std=c99 -Wall -Wextra -Werror -Wno-unused-parameter -Wno-implicit-fallthrough -Iinclude -I/appdb/pg12/pg12.1/include -I. -I./ -I/appdb/pg12/pg12.1/include/postgresql/server -I/appdb/pg12/pg12.1/include/postgresql/internal  -D_GNU_SOURCE -I/usr/include/libxml2   -c -o src/task_states.o src/task_states.c -MMD -MP -MF .deps/task_states.Pogcc -std=gnu99 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -g -O0 -DOPTIMIZER_DEBUG -g3 -gdwarf-2 -fPIC -std=c99 -Wall -Wextra -Werror -Wno-unused-parameter -Wno-implicit-fallthrough -Iinclude -I/appdb/pg12/pg12.1/include -I. -I./ -I/appdb/pg12/pg12.1/include/postgresql/server -I/appdb/pg12/pg12.1/include/postgresql/internal  -D_GNU_SOURCE -I/usr/include/libxml2   -c -o src/entry.o src/entry.c -MMD -MP -MF .deps/entry.Pogcc -std=gnu99 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -g -O0 -DOPTIMIZER_DEBUG -g3 -gdwarf-2 -fPIC -shared -o pg_cron.so src/pg_cron.o src/job_metadata.o src/misc.o src/task_states.o src/entry.o -L/appdb/pg12/pg12.1/lib    -Wl,--as-needed -Wl,-rpath,'/appdb/pg12/pg12.1/lib',--enable-new-dtags  -L/appdb/pg12/pg12.1/lib -lpq cat pg_cron.sql > pg_cron--1.0.sql[pg12@localhost pg_cron]$ make install/bin/mkdir -p '/appdb/pg12/pg12.1/lib/postgresql'/bin/mkdir -p '/appdb/pg12/pg12.1/share/postgresql/extension'/bin/mkdir -p '/appdb/pg12/pg12.1/share/postgresql/extension'/bin/install -c -m 755  pg_cron.so '/appdb/pg12/pg12.1/lib/postgresql/pg_cron.so'/bin/install -c -m 644 .//pg_cron.control '/appdb/pg12/pg12.1/share/postgresql/extension/'/bin/install -c -m 644 .//pg_cron--1.0--1.1.sql .//pg_cron--1.1--1.2.sql pg_cron--1.0.sql '/appdb/pg12/pg12.1/share/postgresql/extension/'[pg12@localhost pg_cron]$

体验
创建扩展

[local:/data/run/pg12]:5120 pg12@testdb=# create extension pg_cron;ERROR:  can only create extension in database postgresDETAIL:  Jobs must be scheduled from the database configured in cron.database_name, since the pg_cron background worker reads job descriptions from this database.HINT:  Add cron.database_name = 'testdb' in postgresql.conf to use the current database.CONTEXT:  PL/pgSQL function inline_code_block line 4 at RAISE[local:/data/run/pg12]:5120 pg12@testdb=# [local:/data/run/pg12]:5120 pg12@testdb=# \c postgresYou are now connected to database "postgres" as user "pg12".[local:/data/run/pg12]:5120 pg12@postgres=# create extension pg_cron;CREATE EXTENSION[local:/data/run/pg12]:5120 pg12@postgres=#

修改系统参数

[local:/data/run/pg12]:5120 pg12@postgres=# select name,setting from pg_settings where name like '%cron%';         name          |  setting  -----------------------+----------- cron.database_name    | postgres cron.host             | localhost cron.log_statement    | on cron.max_running_jobs | 32(4 rows)[local:/data/run/pg12]:5120 pg12@postgres=#

创建job，目的是每个1分钟执行VACUUM FULL

[local:/data/run/pg12]:5120 pg12@postgres=# SELECT cron.schedule('*/1 * * * *', 'VACUUM FULL'); schedule ----------        1(1 row)[local:/data/run/pg12]:5120 pg12@postgres=# [local:/data/run/pg12]:5120 pg12@postgres=# \df cron.schedule                             List of functions Schema |   Name   | Result data type |     Argument data types     | Type --------+----------+------------------+-----------------------------+------ cron   | schedule | bigint           | schedule text, command text | func(1 row)[local:/data/run/pg12]:5120 pg12@postgres=# [local:/data/run/pg12]:5120 pg12@postgres=# \df cron.*                                   List of functions Schema |         Name         | Result data type |     Argument data types     | Type --------+----------------------+------------------+-----------------------------+------ cron   | job_cache_invalidate | trigger          |                             | func cron   | schedule             | bigint           | schedule text, command text | func cron   | unschedule           | boolean          | job_id bigint               | func(3 rows)

日志输出

2020-02-11 17:52:59.935 CST,"pg12","postgres",23764,"[local]",5e427932.5cd4,1,"SELECT",2020-02-11 17:51:46 CST,3/8,0,LOG,00000,"failed to parse entry 1",,,,,,"SELECT cron.schedule('0/1 * * * *', 'VACUUM FULL');",,,"psql"2020-02-11 17:52:59.936 CST,"pg12","postgres",23764,"[local]",5e427932.5cd4,2,"SELECT",2020-02-11 17:51:46 CST,3/8,0,ERROR,22023,"invalid schedule: 0/1 * * * *",,,,,,"SELECT cron.schedule('0/1 * * * *', 'VACUUM FULL');",,,"psql"2020-02-11 17:54:00.001 CST,,,19164,,5e426547.4adc,2,,2020-02-11 16:26:47 CST,1/0,0,LOG,00000,"cron job 1 starting: VACUUM FULL",,,,,,,,,""2020-02-11 17:54:00.740 CST,,,19164,,5e426547.4adc,3,,2020-02-11 16:26:47 CST,1/0,0,LOG,00000,"cron job 1 completed: VACUUM ",,,,,,,,,""2020-02-11 17:55:00.002 CST,,,19164,,5e426547.4adc,4,,2020-02-11 16:26:47 CST,1/0,0,LOG,00000,"cron job 1 starting: VACUUM FULL",,,,,,,,,""2020-02-11 17:55:00.579 CST,,,19164,,5e426547.4adc,5,,2020-02-11 16:26:47 CST,1/0,0,LOG,00000,"cron job 1 completed: VACUUM ",,,,,,,,,""

取消调度

[local:/data/run/pg12]:5120 pg12@postgres=# select cron.unschedule(1); unschedule ------------ t(1 row)[local:/data/run/pg12]:5120 pg12@postgres=#

参考资料
pg_cron