PostgreSQL

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48

#当表没有其他关系时
TRUNCATE TABLE tablename;
#当表中有外键时，要用级联方式删所有关联的数据
TRUNCATE TABLE tablename CASCADE;

# 查看 表大小
select pg_size_pretty(pg_relation_size('table0'));

# 查看配置文件路径, 切换到 postgres 用户执行
psql -c "show config_file"

# 查看版本
select version();

pacman -S postgresql
psql -h 127.0.0.1 -p 5432 -d database0 -U user0

# create database
create database database0;

# create table
create table test(id int, c1 int);
create table table0(field0 json);

# delete table
DROP TABLE table0;
# 查看字段类型
select column_name, data_type from information_schema.columns where table_name='table0';

\l 或 \list meta-command 列出所有数据库
sudo -u postgres psql -c "\l"
用 \c + 数据库名 来进入数据库：
\dt 列出所有数据库表：

# 查看表结构
\d table0

# 比上面多几个字段 Storage  | Stats target | Description
\d+ table0

# Turn off printing of column names and result row count footers, etc. This is equivalent to \t or \pset tuples_only.
\t tuples only on/off, tuples only on 的时候 select 语句的输出不带 header

\h
\?
select * length( "abc"::TEXT)
insert into test select generate_series(1,10000), random()*10;

1
2
3
4
5
6

# https://www.postgresql.org/download/linux/ubuntu/
# install pg_dump
sudo apt install -y postgresql-common
sudo /usr/share/postgresql-common/pgdg/apt.postgresql.org.sh
# ubuntu install pg_dump
sudo apt-get install postgresql-client-17

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20

# -h, host 127.0.0.1
# -p, port 5432
# -t, table: table0, 不加 -t 参数时会导出所有表结构
# -s, 不导出数据
# database: database0
# -F : 指定输出文件的格式，它可以是以下格式之一： c: 自定义格式 d: 目录格式存档 t: tar 文件包 p: SQL 脚本文件
pg_dump -h 127.0.0.1 -U username -W -F t db_name > foo.tar
# -c --clean	创建数据库对象前先清理（删除）它们。
pg_restore -h 127.0.0.1 -U username -W -d db_name -c foo.tar

pg_dump -h 127.0.0.1 -p 5432 -t table_0 -U postgres database0 > foo.sql
pg_dump -h 127.0.0.1 -p 5432 -s -t table_0 -U postgres database0 > foo.sql

# 导出并压缩
pg_dump -d db_name | gzip > db.gz

pg_dump -a -t table_0 "host=127.0.0.1 hostaddr=127.0.0.1 port=5432 user=user_0 password=password_0 dbname=db_0"
# export insert sql
pg_dump -a -t table_0 "host=127.0.0.1 hostaddr=127.0.0.1 port=5432 user=user_0 password=password_0 dbname=db_0" --inserts

1
2
3
4
5
6

# sql
psql -h 127.0.0.1 -p 5432 -t table0 -U postgres -d database0 -f foo.sql

# csv, https://stackoverflow.com/questions/26701735/extra-data-after-last-expected-column-while-trying-to-import-a-csv-file-into-p
\COPY agency (agency_name, agency_url, agency_timezone) FROM 'myFile.txt' CSV HEADER DELIMITER ',';

1
2
3
4
5
6
7

# 按过滤条件导出成 csv, 注意: copy 里面的 select SQL 结尾不能有分号
COPY (
SELECT * FROM nyummy.cimory WHERE city = 'tokio'
) TO '/tmp/foo.csv';

# 导入 csv
COPY table_0 FROM '/path/to/file.csv';

1
2
3

CREATE USER user_0 WITH PASSWORD 'password_0';
CREATE DATABASE db_0 OWNER user_0;
GRANT ALL PRIVILEGES ON DATABASE db_0 TO user_0;

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

# 默认值: off, 改成 on 之后重启 postgresql 就开始写日志了, 日志目录会是 /var/lib/postgresql/data/pgdata/log/
logging_collector = on

# none, ddl, mod, all ---- 控制记录哪些 SQL 语句。
# none 不记录，(默认值)
# ddl 记录所有数据定义命令，比如 CREATE, ALTER, 和 DROP 语句。
# mod 记录所有 ddl 语句, 加上数据修改语句 INSERT,UPDATE等,
# all 记录所有执行的语句，将此配置设置为all可跟踪整个数据库执行的SQL语句。
log_statement = 'all'

# 日志目录名, 默认值: log
# log_directory = 'log'

# 默认文件名
log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log'

log_rotation_age = 1d ----  单个日志文件的生存期，默认 1 天，在日志文件大小没有达到 log_rotation_size 时，一天只生成一个日志文件
log_rotation_size = 10MB  ---- 单个日志文件的大小，如果时间没有超过 log_rotation_age，一个日志文件最大只能到 10M，否则将新生成一个日志文件。
log_truncate_on_rotation = off ---- 当日志文件已存在时，该配置如果为off，新生成的日志将在文件尾部追加，如果为on，则会覆盖原来的日志。
log_duration = off ---- 记录每条SQL语句执行完成消耗的时间，将此配置设置为 on, 用于统计哪些 SQL 语句耗时较长。

10.log_min_duration_statement = -1 # -1 is disabled, 0 logs all statements and their durations, > 0 logs only statements running at least this number of milliseconds

-1表示不可用，0将记录所有SQL语句和它们的耗时，>0只记录那些耗时超过（或等于）这个值（ms）的SQL语句。个人更喜欢使用该配置来跟踪那些耗时较长，可能存在性能问题的SQL语句。虽然使用log_statement和log_duration也能够统计SQL语句及耗时，但是SQL语句和耗时统计结果可能相差很多行，或在不同的文件中，但是log_min_duration_statement会将SQL语句和耗时在同一行记录，更方便阅读。

11.log_connections = off ----是否记录连接日志
12.log_disconnections = off ---- 是否记录连接断开日志

13.log_line_prefix = '%m %p %u %d %r ' ---- 日志输出格式（%m,%p实际意义配置文件中有解释）,可根据自己需要设置（能够记录时间，用户名称，数据库名称，客户端IP和端口，方便定位问题）
14.log_timezone = 'Asia/Shanghai' ---- 日志时区，最好和服务器设置同一个时区，方便问题定位

1

timezone = 'Asia/Shanghai'

1

pg_ctl reload

1
2
3
4
5
6
7

-- TO_DATE(text,format);
SELECT TO_DATE('20170103','YYYYMMDD');

-- to_timestamp(text, text)
to_timestamp('2018-03-12 18:47:35','yyyy-MM-dd hh24:mi:ss')
SELECT to_timestamp('05 Dec 2000', 'DD Mon YYYY');
SELECT to_timestamp('10:49 2023/01/20', 'HH24:MI YYYY/MM/DD');

1
2

SELECT round(cast(date_part('epoch', start_time - end_time)/60/60 as numeric ),1) as time_diff_hours
FROM table0

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34

docker pull postgres:16.4

# 修改配置文件
log_timezone = 'UTC'
timezone = 'Asia/Shanghai'

# docker
# 默认用户名 postgres
docker run --name postgres \
--restart=always \
-p 5432:5432 \
-e POSTGRES_PASSWORD=password0 \
-e PGDATA=/var/lib/postgresql/data/pgdata \
-v postgres-data:/var/lib/postgresql/data \
-d postgres:16.4

# podman
podman run --name postgres \
-p 5432:5432 \
-e POSTGRES_PASSWORD=password0 \
-e PGDATA=/var/lib/postgresql/data/pgdata \
-v postgres-data:/var/lib/postgresql/data \
-d postgres:14.5

psql -h 127.0.0.1 -p 5432 -U postgres
# password: password0

# 重启服务
su -l postgres -c '/opt/pg9.6/bin/pg_ctl -D /mnt/pgdata start'

# 重载配置
su -l postgres -c '/opt/pg9.6/bin/pg_ctl -D /mnt/pgdata reload'

docker run -i --rm postgres:16.4 cat /usr/share/postgresql/postgresql.conf.sample > postgresql.conf

1
2
3
4
5

alter table foo
    rename to bar;

alter table foo
    add time0 timestamptz;

 1
 2
 3
 4
 5
 6
 7
 8
 9
10

-- create table
create table table0(
  field0 json,
  create_time             timestamp with time zone default now(),
  );
 
-- rename column
alter table table_0
    rename column column_foo to column_bar;

1

PGPASSWORD=postgres psql -h 127.0.0.1 -p 5432 -d database0 -U user0  --command 'select version();'

1

PGPASSWORD=postgres psql -h 127.0.0.1 -p 5432 -d database0 -U user0 -f /path/to/foo.sql

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

--查询主键名称
SELECT
    pg_constraint.conname AS pk_name
FROM
    pg_constraint
INNER JOIN pg_class ON pg_constraint.conrelid = pg_class.oid
WHERE
    pg_class.relname = 'table_name_0'
AND pg_constraint.contype = 'p';

--查询主键的详细信息
SELECT
    pg_constraint.conname AS pk_name,
    pg_attribute.attname AS colname,
    pg_type.typname AS typename
FROM
    pg_constraint
INNER JOIN pg_class ON pg_constraint.conrelid = pg_class.oid
INNER JOIN pg_attribute ON pg_attribute.attrelid = pg_class.oid
AND pg_attribute.attnum = pg_constraint.conkey [ 1 ]
INNER JOIN pg_type ON pg_type.oid = pg_attribute.atttypid
WHERE
    pg_class.relname = 'table_name_0'
AND pg_constraint.contype = 'p';

1
2
3
4

SELECT to_char(NOW(), 'YYYY-MM-DD HH24:MI:SS')
-- 时区
to_char(NOW() AT TIME ZONE 'Asia/Dubai','YYYY-MM-DD HH24:MI:SS')

1
2
3
4

select now() + interval '1 days'; 
select now() + interval '1 month'; 
select now() + interval '1 years'; 
select NOW(), NOW() - interval '1 hours 4 minutes';

1

string||string

1
2

-- 单引号转义 ''
UPDATE user SET username = 'Peter''s Name' WHERE id = 1;

1
2
3
4
5
6

SELECT to_number('12345', '9999999999999999999')//12345
SELECT to_number('12345', '99999')//12345
SELECT to_number(''||12345, '9999')//1234，由于模式是4位，结果忽略最后一位；
SELECT to_number('    12345', '9999999999999999999')//12345
SELECT to_number('  ab  ,1,2a3,4b5', '9999999999999999999')//12345，会忽略所有字符串中非数字字符

1
2

CREATE SEQUENCE seq_0 START 1;
CREATE SEQUENCE seq_0 INCREMENT 1 MINVALUE 1 START 1 CACHE 1;  

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11

-- 查看 seq 定义
\d+ seq_0

-- 查看 seq 的当前值, 查询不会导致 sequence 值变化 , 每次查都 是一样的, 如果 没有其它客户端调用 nextval()
SELECT last_value FROM sequence_name;

-- 查看 seq 的下一个值, 每查一次 seq 值 会加 1
SELECT nextval('seq_0')

-- 更新 seq 的值 
select setval('seq_0 ', 88);

1
2
3
4
5

\d [tablename]
"table_name_id_fkey" FOREIGN KEY (id) REFERENCES other_table(id) ....
-- 然后使用下面的命令删除外键：

ALTER TABLE [tablename] DROP CONSTRAINT table_name_id_fkey;

 1
 2
 3
 4
 5
 6
 7
 8
 9
10

SELECT
     tc.constraint_name, tc.table_name, kcu.column_name, 
     ccu.table_name AS foreign_table_name,
     ccu.column_name AS foreign_column_name,
     tc.is_deferrable,tc.initially_deferred
FROM
     information_schema.table_constraints AS tc 
     JOIN information_schema.key_column_usage AS kcu ON tc.constraint_name = kcu.constraint_name
     JOIN information_schema.constraint_column_usage AS ccu ON ccu.constraint_name = tc.constraint_name
WHERE constraint_type = 'FOREIGN KEY' AND tc.table_name = 'table0';

1
2
3
4
5

名字                        别名             描述
character varying [(n)]  varchar [ (n) ]  可变长字符串
character [(n)]          char [ (n) ]     定长字符串
timestamp                                   SQL标准要求仅仅将timestamp类型等于timestamp without time zone 类型
timestamp with time zone   TIMESTAMPTZ       PostgreSQL遵守这个行为。timestamptz 作为 timestamp with time zone 的缩写被接受；这是PostgreSQL 的一个扩展。

1
2
3
4
5
6
7
8
9

show timezone;
select * from pg_timezone_names where abbrev='+04';

# 临时设置时区, 退出 psql 之后失效
set time zone "Asia/Shanghai";

select now();
# 查看数据库可供选择的时区:
select * from pg_timezone_names;

1
2

SUBSTRING(string, start_position, length)
-- str_pos 

1

select * from pg_tables where tablename = 'my_tbl';

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

-- 查看锁
SELECT locker.pid,
       pc.relname,
       locker.mode,
       locker_act.application_name,
       least(query_start, xact_start)                        start_time,
       locker_act.state,
       CASE
           WHEN granted = 'f' THEN
               'wait_lock'
           WHEN granted = 't' THEN
               'get_lock'
           END                                               lock_satus,
       current_timestamp - least(query_start, xact_start) AS runtime,
       locker_act.query
FROM pg_locks locker,
     pg_stat_activity locker_act,
     pg_class pc
WHERE locker.pid = locker_act.pid
  AND NOT locker.pid = pg_backend_pid()
  AND application_name <> 'pg_statsinfod'
  AND locker.relation = pc.oid
  AND pc.reltype <> 0 --and pc.relname='t'
ORDER BY runtime desc;

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16

--查看 PostgreSQL 正在执行的SQL  
SELECT procpid,
       start,
       now() - start AS lap,
       current_query
FROM (SELECT backendid,
             pg_stat_get_backend_pid(S.backendid)            AS procpid,
             pg_stat_get_backend_activity_start(S.backendid) AS start,
             pg_stat_get_backend_activity(S.backendid)       AS current_query
      FROM (SELECT pg_stat_get_backend_idset() AS backendid) AS S) AS S,
     pg_stat_activity pa
WHERE current_query <> '<IDLE>'
  and procpid <> pg_backend_pid()
  and pa.pid = s.procpid
  and pa.state <> 'idle'
ORDER BY lap DESC;

1
2

# 查找是否有 waiting  
ps -ef|grep postgres | grep wait  

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14

--查看当前库表和索引的的大小并排序显示前20条
SELECT nspname,
       relname,
       relkind                                       as "type",
       pg_size_pretty(pg_table_size(C.oid))          AS size,
       pg_size_pretty(pg_indexes_size(C.oid))        AS idxsize,
       pg_size_pretty(pg_total_relation_size(C.oid)) as "total"
FROM pg_class C
         LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace)
WHERE nspname NOT IN ('pg_catalog', 'information_schema')
  AND nspname !~ '^pg_toast'
  AND relkind IN ('r', 'i')
ORDER BY pg_total_relation_size(C.oid) DESC
LIMIT 20;

 1
 2
 3
 4
 5
 6
 7
 8
 9
10

-- 最大连接数
show max_connections;
-- 当前连接
select * from pg_stat_activity;
select datname from pg_stat_activity group by datname;
select state from pg_stat_activity group by state;
select * from pg_stat_activity where datname='database0' limit 1;
select pid, query_start,query from pg_stat_activity where datname='database0' and state='idle';
-- 释放空闲连接
SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE state='idle';

1
2
3
4
5

COPY (
  SELECT foo, bar FROM table0
)
TO '/tmp/foo.csv'
WITH csv header;

1
2
3

psql
\c database0
\copy table0(field0,field1,field2,"field3") from '/home/wiloon/tmp/foo.csv' delimiter ',' csv header;

1

select array_length(regexp_split_to_array(config,'"id":'),1)-1 from xxx;

1
2
3
4
5
6
7

### 操作系统上查看 WAL 发送进程或 WAL 接收进程
ps -ef | grep "wal" | grep -v "grep"
# 主库会有 postgres: walwriter, postgres: walsender 进程
# 从库只有 postgres: walreceiver 进程

# 通过 pg_controldata 命令查看数据库控制信息，内容包含 WAL 日志信息、checkpoint、数据块等信息，通过 Databasecluster state 信息可判断是主库还是备库
pg_controldata | grep cluster

1
2
3
4

-- psql 连接到 DB 之后, 可以这样判断
SELECT pg_is_in_recovery();
-- You can use pg_is_in_recovery() which returns True if recovery is still in progress(so the server is running in standby mode). Check the System Administration Functions for further informations.
-- 如果返回 t 说明是备库，返回 f 是主库

1
2
3
4
5

create table test(id int, c1 int);  
insert into test select generate_series(1,10000), random()*10;
select * from test limit 10;
select c1,count(*)  from test group by c1;
select c1,count(*), count(*) filter (where id<1000) from test group by c1;

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18

--把'1234'转成整数

select cast('1234' as integer ) ;

--用substring截取字符串，从第8个字符开始截取2个字符：结果是12

select cast(substring('1234abc12',8,2) as integer)

---使用to_number函数来转换成整数

---to_number(text, text)  返回的类型 numeric     把字串转换成numeric   to_number('12,454.8-', '99G999D9S')

select to_number('12121','999999999')
————————————————

                            版权声明：本文为博主原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接和本声明。
                        
原文链接：https://blog.csdn.net/xingxiupaioxue/article/details/78295118

1
2

-- 模糊查询，并且不区分大小写
select * from student where name ilike '%tom%'

1
2
3
4
5
6
7

CREATE INDEX index_0 ON table_0 (column_0);

select * from pg_indexes where tablename='network_discovery_routing_data';
select * from pg_statio_all_indexes where relname='network_discovery_routing_data';

select pg_relation_size('network_discovery_routing_data_time_stamp_idx');
select pg_relation_size('constraint_routing_id_time_stamp');

1

set enable_seqscan=off;set enable_bitmapscan = off;set enable_tidscan = off;explain (analyze,buffers,verbose) select count(*) from aken01;

1

set enable_seqscan = off;