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+# PostgreSQL 常用命令
+
+## 连接数据库
+
+```bash
+# 查看版本
+psql -V
+
+# 连接数据库
+psql -U postgres -h 127.0.0.1 -p 5432
+
+# 连接指定数据库
+psql -U postgres -d database_name -h 127.0.0.1 -p 5432
+
+# 使用密码文件连接
+psql -U postgres -h 127.0.0.1 -p 5432 -d database_name -f query.sql
+
+# 退出交互界面
+\q
+```
+
+## 宝塔 aapanel 安装扩展
+```bash
+ss -tlnp | grep postgres
+
+cd /usr/local/pgsql
+make -C contrib -j"$(nproc)" PG_CONFIG=/www/server/pgsql/bin/pg_config
+make -C contrib install PG_CONFIG=/www/server/pgsql/bin/pg_config
+
+/www/server/pgsql/bin/psql -U postgres -d postgres -c "SELECT name FROM pg_available_extensions ORDER BY name;"
+
+sudo su - postgres
+/www/server/pgsql/bin/pg_ctl restart -D /www/server/pgsql/data
+
+# 重新创建扩展并验证
+/www/server/pgsql/bin/psql -U postgres -d database_name -p 5432 -c "CREATE EXTENSION IF NOT EXISTS citext;"
+/www/server/pgsql/bin/psql -U postgres -d database_name -p 5432 -c "\dx"
+
+# 可选（最常用的扩展）
+CREATE EXTENSION IF NOT EXISTS pg_trgm;
+CREATE EXTENSION IF NOT EXISTS unaccent;
+CREATE EXTENSION IF NOT EXISTS citext;
+CREATE EXTENSION IF NOT EXISTS hstore;
+CREATE EXTENSION IF NOT EXISTS "uuid-ossp";
+CREATE EXTENSION IF NOT EXISTS pg_stat_statements;
+```
+
+## 数据库管理
+
+```sql
+-- 列出所有数据库
+\l
+-- 或
+SELECT datname FROM pg_database;
+
+-- 创建数据库
+CREATE DATABASE database_name;
+
+-- 删除数据库
+DROP DATABASE database_name;
+
+-- 切换数据库
+\c database_name
+
+-- 查看当前数据库
+SELECT current_database();
+
+-- 查看数据库大小
+SELECT pg_size_pretty(pg_database_size('database_name'));
+
+-- 查看所有数据库大小
+SELECT datname, pg_size_pretty(pg_database_size(datname)) AS size 
+FROM pg_database 
+ORDER BY pg_database_size(datname) DESC;
+```
+
+## 用户和权限管理
+
+```sql
+-- 列出所有用户
+\du
+-- 或
+SELECT usename FROM pg_user;
+
+-- 创建用户
+CREATE USER username WITH PASSWORD 'password';
+
+-- 创建超级用户
+CREATE USER username WITH SUPERUSER PASSWORD 'password';
+
+-- 修改用户密码
+ALTER USER username WITH PASSWORD 'new_password';
+
+-- 删除用户
+DROP USER username;
+
+-- 授予权限
+GRANT ALL PRIVILEGES ON DATABASE database_name TO username;
+GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA public TO username;
+
+-- 撤销权限
+REVOKE ALL PRIVILEGES ON DATABASE database_name FROM username;
+
+-- 查看用户权限
+\du username
+```
+
+## 表管理
+
+```sql
+-- 列出所有表
+\dt
+-- 或
+SELECT tablename FROM pg_tables WHERE schemaname = 'public';
+
+-- 列出所有表（包括系统表）
+\dt+
+
+-- 查看表结构
+\d table_name
+\d+ table_name  -- 详细信息
+
+-- 查看表大小
+SELECT pg_size_pretty(pg_total_relation_size('table_name')) AS total_size,
+       pg_size_pretty(pg_relation_size('table_name')) AS table_size,
+       pg_size_pretty(pg_indexes_size('table_name')) AS indexes_size;
+
+-- 查看所有表大小
+SELECT 
+    schemaname,
+    tablename,
+    pg_size_pretty(pg_total_relation_size(schemaname||'.'||tablename)) AS size
+FROM pg_tables
+WHERE schemaname = 'public'
+ORDER BY pg_total_relation_size(schemaname||'.'||tablename) DESC;
+
+-- 查看表行数
+SELECT COUNT(*) FROM table_name;
+
+-- 查看表统计信息
+SELECT * FROM pg_stat_user_tables WHERE relname = 'table_name';
+```
+
+## 索引管理
+
+```sql
+-- 列出所有索引
+\di
+\di table_name*
+-- 或
+SELECT indexname FROM pg_indexes WHERE tablename = 'table_name';
+
+-- 查看索引详细信息
+\d+ index_name
+
+-- 创建索引
+CREATE INDEX idx_name ON table_name(column_name);
+
+-- 创建唯一索引
+CREATE UNIQUE INDEX idx_name ON table_name(column_name);
+
+-- 创建复合索引
+CREATE INDEX idx_name ON table_name(column1, column2);
+
+-- 创建 GIN 索引（用于全文搜索、数组等）
+CREATE INDEX idx_name ON table_name USING GIN(column_name gin_trgm_ops);
+
+-- 创建 GIST 索引（用于几何数据、范围等）
+CREATE INDEX idx_name ON table_name USING GIST(column_name);
+
+-- 删除索引
+DROP INDEX index_name;
+
+-- 重建索引（解决索引碎片）
+REINDEX INDEX index_name;
+REINDEX TABLE table_name;
+REINDEX DATABASE database_name;
+
+-- 查看索引使用情况
+SELECT 
+    schemaname,
+    tablename,
+    indexname,
+    idx_scan,
+    idx_tup_read,
+    idx_tup_fetch
+FROM pg_stat_user_indexes
+ORDER BY idx_scan DESC;
+```
+
+## 查询和分析
+
+```sql
+-- 查看执行计划
+EXPLAIN SELECT * FROM table_name WHERE condition;
+EXPLAIN ANALYZE SELECT * FROM table_name WHERE condition;
+EXPLAIN (ANALYZE, BUFFERS, VERBOSE) SELECT * FROM table_name WHERE condition;
+
+-- 查看慢查询（需要启用 pg_stat_statements）
+SELECT 
+    query,
+    calls,
+    total_exec_time,
+    mean_exec_time,
+    max_exec_time
+FROM pg_stat_statements
+ORDER BY total_exec_time DESC
+LIMIT 10;
+
+-- 查看当前正在执行的查询
+SELECT pid, usename, application_name, state, query, query_start 
+FROM pg_stat_activity 
+WHERE state = 'active';
+
+-- 查看等待锁的查询
+SELECT 
+    blocked_locks.pid AS blocked_pid,
+    blocking_locks.pid AS blocking_pid,
+    blocked_activity.usename AS blocked_user,
+    blocking_activity.usename AS blocking_user,
+    blocked_activity.query AS blocked_statement,
+    blocking_activity.query AS blocking_statement
+FROM pg_catalog.pg_locks blocked_locks
+JOIN pg_catalog.pg_stat_activity blocked_activity ON blocked_activity.pid = blocked_locks.pid
+JOIN pg_catalog.pg_locks blocking_locks ON blocking_locks.locktype = blocked_locks.locktype
+JOIN pg_catalog.pg_stat_activity blocking_activity ON blocking_activity.pid = blocking_locks.pid
+WHERE NOT blocked_locks.granted AND blocking_locks.granted;
+
+-- 终止查询
+SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE pid = <pid>;
+```
+
+## 扩展管理
+
+```sql
+-- 列出所有已安装的扩展
+\dx
+-- 或
+SELECT extname, extversion FROM pg_extension;
+
+-- 查看可用扩展
+SELECT * FROM pg_available_extensions;
+
+-- 安装扩展
+CREATE EXTENSION extension_name;
+
+-- 安装扩展（如果不存在）
+CREATE EXTENSION IF NOT EXISTS extension_name;
+
+-- 卸载扩展
+DROP EXTENSION extension_name;
+
+-- pg_trgm 扩展（用于相似度搜索）
+-- 查看已安装的扩展，确认包含 pg_trgm
+SELECT extname, extversion FROM pg_extension WHERE extname = 'pg_trgm';
+
+-- 启用 pg_trgm 扩展（数据库级生效，超级用户权限）
+CREATE EXTENSION IF NOT EXISTS pg_trgm;
+
+-- 降低阈值（默认0.3），匹配更多相似结果（测试用）
+SET pg_trgm.similarity_threshold = 0.2;
+
+-- 执行相似匹配查询
+SELECT * FROM test_trgm WHERE similarity(content, '三四五') > 0.2;
+
+-- 重建GIN索引（定期执行，比如每月1次） 解决索引碎片
+REINDEX INDEX idx_test_trgm_content;
+```
+
+## 备份和恢复
+
+```bash
+# 备份数据库（自定义格式，支持压缩）
+pg_dump -U postgres -h 127.0.0.1 -d database_name -F c -f backup.dump
+
+# 备份数据库（SQL格式）
+pg_dump -U postgres -h 127.0.0.1 -d database_name -f backup.sql
+
+# 备份单个表
+pg_dump -U postgres -h 127.0.0.1 -d database_name -t table_name -f table_backup.sql
+
+# 仅备份结构（不包含数据）
+pg_dump -U postgres -h 127.0.0.1 -d database_name -s -f schema.sql
+
+# 仅备份数据（不包含结构）
+pg_dump -U postgres -h 127.0.0.1 -d database_name -a -f data.sql
+
+# 恢复数据库（从自定义格式）
+pg_restore -U postgres -h 127.0.0.1 -d database_name backup.dump
+
+# 恢复数据库（从SQL文件）
+psql -U postgres -h 127.0.0.1 -d database_name -f backup.sql
+
+# 备份所有数据库
+pg_dumpall -U postgres -h 127.0.0.1 -f all_databases.sql
+
+# 恢复所有数据库
+psql -U postgres -h 127.0.0.1 -f all_databases.sql
+```
+
+## 性能监控
+
+```sql
+-- 查看数据库连接数
+SELECT count(*) FROM pg_stat_activity;
+
+-- 查看最大连接数
+SHOW max_connections;
+
+-- 查看当前配置
+SHOW ALL;
+
+-- 查看共享缓冲区使用情况
+SELECT * FROM pg_stat_bgwriter;
+
+-- 查看表统计信息
+SELECT 
+    schemaname,
+    tablename,
+    n_tup_ins AS inserts,
+    n_tup_upd AS updates,
+    n_tup_del AS deletes,
+    n_live_tup AS live_rows,
+    n_dead_tup AS dead_rows,
+    last_vacuum,
+    last_autovacuum,
+    last_analyze,
+    last_autoanalyze
+FROM pg_stat_user_tables
+ORDER BY n_live_tup DESC;
+
+-- 查看缓存命中率
+SELECT 
+    sum(heap_blks_read) as heap_read,
+    sum(heap_blks_hit)  as heap_hit,
+    (sum(heap_blks_hit) - sum(heap_blks_read)) / sum(heap_blks_hit) as ratio
+FROM pg_statio_user_tables;
+```
+
+## 维护操作
+
+```sql
+-- 分析表（更新统计信息）
+ANALYZE table_name;
+ANALYZE;  -- 分析所有表
+
+-- 清理表（VACUUM）
+VACUUM table_name;
+VACUUM FULL table_name;  -- 完全清理，会锁表
+VACUUM ANALYZE table_name;  -- 清理并分析
+
+-- 自动清理（后台进程）
+-- 查看自动清理配置
+SHOW autovacuum;
+
+-- 查看需要清理的表
+SELECT 
+    schemaname,
+    tablename,
+    n_dead_tup,
+    n_live_tup,
+    round(n_dead_tup * 100.0 / NULLIF(n_live_tup, 0), 2) AS dead_ratio
+FROM pg_stat_user_tables
+WHERE n_dead_tup > 0
+ORDER BY dead_ratio DESC;
+```
+
+## 实用命令
+
+```sql
+-- 查看当前时间
+SELECT NOW();
+
+-- 查看时区
+SHOW timezone;
+SELECT current_setting('timezone');
+
+-- 设置时区
+SET timezone = 'Asia/Shanghai';
+
+-- 查看当前用户
+SELECT current_user;
+
+-- 查看当前数据库
+SELECT current_database();
+
+-- 查看 PostgreSQL 版本
+SELECT version();
+
+-- 查看服务器配置
+SHOW config_file;  -- 配置文件路径
+SHOW data_directory;  -- 数据目录
+
+-- 复制表结构
+CREATE TABLE new_table (LIKE old_table INCLUDING ALL);
+
+-- 复制表数据
+INSERT INTO new_table SELECT * FROM old_table;
+
+-- 查看序列
+\ds
+SELECT sequence_name FROM information_schema.sequences;
+
+-- 重置序列
+ALTER SEQUENCE sequence_name RESTART WITH 1;
+```
+
+## 安装扩展（Ubuntu/Debian）
+
+```bash
+# 替换版本号（如 14, 15, 16）为你的 PostgreSQL 版本
+apt-get update
+apt-get install -y postgresql-contrib-16
+
+# 安装其他常用扩展
+apt-get install -y postgresql-16-pg-stat-statements
+```
+
+## 常用 psql 命令
+
+```bash
+# 在 psql 交互界面中
+\l          # 列出所有数据库
+\c dbname   # 连接到数据库
+\dt         # 列出当前数据库的所有表
+\d table    # 显示表结构
+\di         # 列出索引
+\du         # 列出用户
+\dx         # 列出扩展
+\df         # 列出函数
+\dn         # 列出模式
+\q          # 退出
+\?          # 帮助
+\h          # SQL 命令帮助
+\timing     # 显示查询执行时间
+\x          # 扩展显示模式（列转行）
+\copy       # 导入/导出 CSV
+```
+
+## 导入/导出 CSV
+
+```sql
+-- 导出表到 CSV
+\copy table_name TO '/path/to/file.csv' WITH CSV HEADER;
+
+-- 从 CSV 导入
+\copy table_name FROM '/path/to/file.csv' WITH CSV HEADER;
+
+-- 使用 COPY 命令（需要超级用户权限）
+COPY table_name TO '/path/to/file.csv' WITH CSV HEADER;
+COPY table_name FROM '/path/to/file.csv' WITH CSV HEADER;
+```