Cpp

databases/postgresql.sh

@@ -0,0 +1,100 @@
+# *****************************************************************************
+# BASICS
+# *****************************************************************************
+pg_dump -h hostname -U username -p port dbname > file.sql           # Export database
+psql -h hostname -U username -d dbname -f file.sql                 # Import database
+
+psql -U username -c "SELECT pid, query, state FROM pg_stat_activity;" 
+# Show running queries
+
+psql -U username -c "SHOW max_connections;"                        # Show max connections
+psql -U username -c "SHOW superuser_reserved_connections;"         # Reserved connections for superuser
+ALTER SYSTEM SET max_connections = 150;                            # Change max connections (requires restart)
+
+psql -U postgres -c "GRANT ALL PRIVILEGES ON DATABASE dbname TO username;" 
+# Grant all privileges to user
+
+psql -U postgres -c "CREATE ROLE newuser LOGIN PASSWORD 'password';" 
+# Create user (role with login)
+
+# *****************************************************************************
+# Database and Table Operations
+# *****************************************************************************
+CREATE DATABASE database_name;                        -- Create database
+DROP DATABASE database_name;                          -- Delete database
+
+CREATE TABLE table_name (
+    column1 datatype,
+    column2 datatype
+);                                                     -- Create table
+
+DROP TABLE table_name;                                -- Delete table
+\d                                                    -- Show tables in current DB (psql)
+\d table_name                                         -- Describe table structure
+
+# *****************************************************************************
+# Data Manipulation
+# *****************************************************************************
+INSERT INTO table_name (column1, column2) VALUES (value1, value2);   -- Insert data
+
+UPDATE table_name SET column1 = value WHERE condition;               -- Update records
+
+DELETE FROM table_name WHERE condition;                              -- Delete data
+
+SELECT column1, column2 FROM table_name WHERE condition;             -- Select data
+
+# *****************************************************************************
+Backup and Restore
+# *****************************************************************************
+pg_dump -U username -t table1 -t table2 dbname > tables.sql     # Backup specific tables
+psql -U username -d dbname -f tables.sql                        # Restore specific tables
+
+# *****************************************************************************
+# User Management and Security
+# *****************************************************************************
+REVOKE privilege ON table_name FROM username;                  -- Revoke privileges
+
+DROP ROLE username;                                            -- Drop user/role
+
+ALTER ROLE username WITH PASSWORD 'newpassword';               -- Change user password
+
+# *****************************************************************************
+# Performance and Maintenance
+# *****************************************************************************
+VACUUM table_name;                                             -- Clean dead tuples
+VACUUM FULL table_name;                                        -- Heavy vacuum (locks table)
+
+ANALYZE table_name;                                            -- Update stats
+
+REINDEX TABLE table_name;                                      -- Rebuild indexes
+
+CHECKPOINT;                                                    -- Force checkpoint
+
+# *****************************************************************************
+# Advanced Queries
+# *****************************************************************************
+SELECT * FROM table1 
+JOIN table2 ON table1.column = table2.column;                  -- JOIN
+
+SELECT * FROM (
+    SELECT column FROM table_name
+) AS sub;                                                      -- Subquery
+
+SELECT column, COUNT(*) 
+FROM table_name 
+GROUP BY column;                                               -- Aggregation
+
+# *****************************************************************************
+# System Information
+# *****************************************************************************
+SELECT version();                                              -- PostgreSQL version
+SELECT usename, usesuper FROM pg_user;                         -- List users
+
+# *****************************************************************************
+# Miscellaneous
+# *****************************************************************************
+SELECT * FROM pg_stat_activity;                                -- Show active queries
+
+SET log_statement = 'all';                                     -- Enable query logging (session only)
+
+SHOW data_directory;                                            -- Show data directory