經常使用 PostgreSQL 腳本

數據定義

數據庫

-- 建立數據庫
-- 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';
-- OR WINDOWS
CREATE DATABASE {database_name} WITH OWNER = {database_user} ENCODING 'UTF8' LC_COLLATE = 'Chinese (Simplified)_China.936' LC_CTYPE = 'Chinese (Simplified)_China.936';

-- 複製數據庫
-- 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};

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

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

-- 驗證 UUID 擴展
SELECT uuid_generate_v4();

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

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

函數

-- 隱式將整形轉換成字符串，可是會有一些問題，參考 https://stackoverflow.com/questions/50025750/postgres-convert-integer-into-text。一般狀況下仍是建議使用 CAST 函數來實現。
-- 使用場景：在數據庫遷移的時候（好比 Microsoft SQL Server 轉成 PostgreSQL，Microsoft SQL Server 默認是支持的）須要隱式轉換，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

-- 建立索引
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}');

-- 查詢全部索引
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));

-- 查詢全部索引，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%';

數據查詢和操做

-- 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 中建立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}';

-- 分配全部權限
-- 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;

運行維護

-- 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
pg_dump --host {host_name} --port {port} --username {database_user} --format c --blobs --verbose --file {file_path} {database_name}

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

其餘

-- 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

# 打開數據庫鏈接
# host_name
# database_user
psql -h {host_name} -U {database_user}

# 列出全部的數據庫
\l

# 鏈接數據
# database_name
\c {database_name}

File Locations

SHOW data_directory;
SHOW config_file;
SHOW hba_file;

修改記錄

• 2020-03-23 21:44 新增數據查詢和操做的 SQL
• 2020-03-17 18:29 新增 File Locations 節點
• 2020-03-12 23:02 修改備份腳本：增長了 port 參數；將縮寫命令改爲完整參數命令，便於閱讀