常用 PostgreSQL 腳本

數據定義

數據庫

-- 創建數據庫
-- https://www.postgresql.org/docs/current/static/multibyte.html
-- database_name，數據庫名稱
-- database_user，用戶名
CREATE DATABASE {database_name} WITH OWNER = {database_user};
CREATE DATABASE {database_name} OWNER {database_user};

-- LC_COLLATE：string sort order
-- LC_CTYPE：character classification
-- database_name，數據庫名稱
-- database_user，用戶名
CREATE DATABASE {database_name} WITH OWNER = {database_user} ENCODING 'UTF8' LC_COLLATE = 'zh_CN.UTF-8' LC_CTYPE = 'zh_CN.UTF-8' TEMPLATE = template0;
-- OR WINDOWS
CREATE DATABASE {database_name} WITH OWNER = {database_user} ENCODING 'UTF8' LC_COLLATE = 'Chinese (Simplified)_China.936' LC_CTYPE = 'Chinese (Simplified)_China.936' TEMPLATE = template0;

-- 復制數據庫
-- database_name，數據庫名稱
-- database_user，用戶名
-- original_database_name，原始數據庫名稱
CREATE DATABASE {database_name} WITH TEMPLATE {original_database_name} OWNER {database_user};

-- 重命名數據庫
-- database_name，數據庫名稱
-- new_database_name，新的數據庫名稱
SELECT
    pg_terminate_backend (pid)
FROM
    pg_stat_activity
WHERE
    datname = '{database_name}';
ALTER DATABASE {database_name} RENAME TO {new_database_name};

表

-- 新增列
-- table_name，表名
-- column_name，列名
-- column_type，列類型
ALTER TABLE {table_name} ADD COLUMN IF NOT EXISTS {column_name} {column_type} [NULL | NOT NULL];

擴展

-- 創建 UUID 擴展
CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

-- 驗證 UUID 擴展
SELECT uuid_generate_v4();

-- 創建 cube 擴展
CREATE EXTENSION IF NOT EXISTS cube;

-- 創建 earthdistance 擴展
CREATE EXTENSION IF NOT EXISTS earthdistance;

函數

-- 隱式將整形轉換成字符串，但是會有一些問題，參考 https://stackoverflow.com/questions/50025750/postgres-convert-integer-into-text。通常情況下還是建議使用 CAST 函數來實現。
-- 使用場景：在數據庫遷移的時候（比如 Microsoft SQL Server 轉成 PostgreSQL，Microsoft SQL Server 默認是支持的）需要隱式轉換，以達到快速實現的目的
CREATE FUNCTION pg_catalog.text(integer) RETURNS text STRICT IMMUTABLE LANGUAGE SQL AS 'SELECT textin(int4out($1));';
CREATE CAST (integer AS text) WITH FUNCTION pg_catalog.text(integer) AS IMPLICIT;
COMMENT ON FUNCTION pg_catalog.text(integer) IS 'convert integer to text';
CREATE FUNCTION pg_catalog.text(bigint) RETURNS text STRICT IMMUTABLE LANGUAGE SQL AS 'SELECT textin(int8out($1));';
CREATE CAST (bigint AS text) WITH FUNCTION pg_catalog.text(bigint) AS IMPLICIT;
COMMENT ON FUNCTION pg_catalog.text(bigint) IS 'convert bigint to text';

索引

-- 創建索引
CREATE INDEX IF NOT EXISTS {index_name} ON {table_name} USING btree ({column_name});

-- Query the indexes of a table
-- table_name，表名
SELECT * FROM pg_indexes WHERE tablename IN ('{table_name}');

-- 查詢所有索引
SELECT
    i.relname AS indname ,
    i.relowner AS indowner ,
    idx.indrelid::REGCLASS ,
    am.amname AS indam ,
    idx.indkey ,
    ARRAY(
    SELECT
        pg_get_indexdef(idx.indexrelid,
        k + 1,
        TRUE)
    FROM
        GENERATE_SUBSCRIPTS(idx.indkey, 1) AS k
    ORDER BY
        k) AS indkey_names ,
    idx.indexprs IS NOT NULL AS indexprs ,
    idx.indpred IS NOT NULL AS indpred
FROM
    pg_index AS idx
JOIN pg_class AS i ON
    i.oid = idx.indexrelid
JOIN pg_am AS am ON
    i.relam = am.oid
JOIN pg_namespace AS ns ON
    ns.oid = i.relnamespace
    AND ns.nspname = ANY (CURRENT_SCHEMAS(FALSE));

-- 查詢所有索引，排除系統表
SELECT
    U.usename AS user_name,
    ns.nspname AS schema_name,
    idx.indrelid :: REGCLASS AS table_name,
    i.relname AS index_name,
    idx.indisunique AS is_unique,
    idx.indisprimary AS is_primary,
    am.amname AS index_type,
    idx.indkey,
    ARRAY(
    SELECT
        pg_get_indexdef(idx.indexrelid,
        k + 1,
        TRUE)
    FROM
        GENERATE_SUBSCRIPTS(idx.indkey, 1) AS k
    ORDER BY
        k ) AS index_keys,
    (idx.indexprs IS NOT NULL)
    OR (idx.indkey::INT[] @> ARRAY[0]) AS is_functional,
    idx.indpred IS NOT NULL AS is_partial
FROM
    pg_index AS idx
JOIN pg_class AS i ON
    i.oid = idx.indexrelid
JOIN pg_am AS am ON
    i.relam = am.oid
JOIN pg_namespace AS NS ON
    i.relnamespace = NS.OID
JOIN pg_user AS U ON
    i.relowner = U.usesysid
WHERE
    NOT nspname LIKE 'pg%';

數據查詢和操作

-- 檢查不存在則寫入
INSERT INTO {table_name}({column_name1} [, {column_name2}, ...])
SELECT {column_value1} [, {column_value2}, ...]
WHERE NOT EXISTS (
    SELECT 1 FROM {table_name} WHERE ...
)

權限控制

-- CREATE USER OR ROLE，PostgreSQL 中創建用戶和角色是等效的
-- role_name，用戶角色名稱
-- user_password，用戶密碼
-- user_name，用戶角色名稱
CREATE ROLE {role_name} WITH CREATEDB CREATEROLE LOGIN PASSWORD '{user_password}';
CREATE user {user_name} PASSWORD '{user_password}';

-- 分配所有權限
-- database_name，數據庫名稱
-- database_user，數據庫用戶
GRANT ALL PRIVILEGES ON {database_name} TO {database_user};

-- 修改表的 Owner
-- table_name，表名
-- database_user，數據庫用戶
ALTER TABLE {table_name} OWNER TO {database_user};

-- 分配 FUNCTION 的權限給指定用戶
-- function_name，函數名稱
-- parameter1_type，第一個函數參數類型
-- parameter2_type，第二個函數參數類型
-- database_user，數據庫用戶
GRANT EXECUTE ON FUNCTION {function_name}([{parameter1_type}, {parameter2_type}, ...]) TO {database_user};

-- 修改 FUNCTION 的 Owner
-- function_name，函數名稱
-- parameter1_type，第一個函數參數類型
-- parameter2_type，第二個函數參數類型
-- database_user，數據庫用戶
ALTER FUNCTION {function_name}([{parameter1_type}, {parameter2_type}, ...]) OWNER TO {database_user};

運行分析

-- 查詢當前數據庫 TOP 20 大表
SELECT table_name
    ,pg_size_pretty(pg_relation_size(table_schema || '.' || table_name)) AS size
FROM information_schema.tables
ORDER BY pg_relation_size(table_schema || '.' || table_name) DESC LIMIT 20;

-- 查詢單個表大小
-- table_name，表名
SELECT pg_size_pretty(pg_relation_size({table_name}));

-- 查詢數據庫活動的查詢
SELECT current_timestamp - query_start AS runtime
    ,query_start
    ,datname
    ,pid
    ,query
FROM pg_stat_activity
WHERE query_start IS NOT NULL
ORDER BY 1 DESC limit 20;

-- 查詢系統中誰阻塞了誰
-- From：《PostgreSQL for Data Architects 數據架構師的 PostgreSQL 修煉》 Jayadevan Maymala 著 戚長松 譯
SELECT
    waiting1.pid AS waiting_pid,
    waiting2.usename AS waiting_user,
    waiting2.query AS waiting_statement,
    blocking1.pid AS blocking_pid,
    blocking2.usename AS blocking_user,
    blocking2.query AS blocking_statement
FROM pg_locks AS waiting1
JOIN pg_stat_activity AS waiting2
    ON waiting1.pid = waiting2.pid
JOIN pg_locks AS blocking1
    ON waiting1.transactionid = blocking1.transactionid
        AND waiting1.pid != blocking1.pid
JOIN pg_stat_activity AS blocking2
    ON blocking1.pid = blocking2.pid
WHERE NOT waiting1.GRANTED;

運行維護

-- Check server version
SELECT VERSION();

-- Cancel Processes by pid
SELECT pg_cancel_backend(pid int);

-- Terminate Processes by pid
SELECT pg_terminate_backend(pid int);

-- Kill all existing connections in the original database
-- source_db，數據庫名稱
SELECT pg_terminate_backend(pg_stat_activity.pid)
FROM pg_stat_activity
WHERE pg_stat_activity.datname = '{source_db}'
AND pid <> pg_backend_pid();

-- garbage-collect and optionally analyze a database
-- table_name，數據庫表名
VACUUM {table_name};
VACUUM FULL {table_name};

配置

-- 修改 max_locks_per_transaction
ALTER SYSTEM SET max_locks_per_transaction = 300;

-- 重載配置信息，使配置生效
-- pg_hba.conf
SELECT pg_reload_conf();

備份還原

# host_name，主機
# database_user，數據庫用戶
# file_path，備份文件路徑
# database_name，數據庫名稱
# --blobs 在轉儲中包含大對象。除非指定了--schema, --table, --schema-only開關，否則這是默認行為。因此-b 開關僅用於在選擇性轉儲的時候添加大對象。
# --verbose 指定冗余模式。這樣將令pg_dump 輸出詳細的對象評注以及轉儲文件的啟停時間和進度信息到標准錯誤上。
# --table=table
# --exclude-table=table
pg_dump --host {host_name} --port {port} --username {database_user} --format c --blobs --verbose --file {file_path} {database_name}
pg_dump --host {host_name} --port {port} --username {database_user} --format c --table={table1_name} --table={table2_name} --verbose --file {file_path} {database_name}

pg_restore --host {host_name} --port {port} --username {database_user} --no-owner --dbname {database_name} {file_path}

其他

-- Prepare a statement for execution
PREPARE foo(TEXT, TEXT, TEXT) AS
SELECT *
FROM foobar
WHERE foo = $1
    AND bar = $2
    OR baz = $3
EXECUTE foo('foo', 'bar', 'baz');
DEALLOCATE foo;

時間處理

-- 查詢時間差
-- begin_time
-- end_time
SELECT EXTRACT(epoch FROM ({begin_time} - {end_time}));

-- Query the last month in format 'YYYYMM'
SELECT to_char(date_trunc('month', current_date - interval '1' month), 'YYYYMM');

psql

# 打開數據庫連接
# host_name
# database_user
psql -h {host_name} -U {database_user}

# 列出所有的數據庫
\l

# 連接數據
# database_name
\c {database_name}

File Locations

SHOW data_directory;
SHOW config_file;
SHOW hba_file;

修改記錄

• 2020-07-16 19:38 新增了查詢阻塞情況的腳本
• 2020-06-12 19:15 新增了 pg_dump 指定表的腳本
• 2020-06-03 10:27 新增修改數據庫名的 SQL
• 2020-04-28 16:26 新增查詢服務器版本的 SQL
• 2020-03-23 21:44 新增數據查詢和操作的 SQL
• 2020-03-17 18:29 新增 File Locations 節點
• 2020-03-12 23:02 修改備份腳本：增加了 port 參數；將縮寫命令改成完整參數命令，便於閱讀