PostgreSQL查询表的大小

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数据库中单个表的大小（不包含索引）

select pg_size_pretty(pg_relation_size('表名'));

查出所有表（包含索引）并排序

SELECT table_schema || '.' || table_name AS table_full_name, pg_size_pretty(pg_total_relation_size('"' || table_schema || '"."' || table_name || '"')) AS size 
FROM information_schema.tables
ORDER BY
pg_total_relation_size('"' || table_schema || '"."' || table_name || '"') DESC limit 20

查看数据库大小

select pg_database_size('david');

查看存储一个指定的数值需要的字节数

//数值类型长度一个是4
select pg_column_size(1000); 
pg_column_size  = 4

//每个英文一个长度
select pg_column_size('test'); 
pg_column_size  = 5

//每个中文3个长度
select pg_column_size('中国');                         
pg_column_size  = 7

查出表大小按大小排序并分离data与index

SELECT
table_name,
pg_size_pretty(table_size) AS table_size,
pg_size_pretty(indexes_size) AS indexes_size,
pg_size_pretty(total_size) AS total_size
FROM (
SELECT
table_name,
pg_table_size(table_name) AS table_size,
pg_indexes_size(table_name) AS indexes_size,
pg_total_relation_size(table_name) AS total_size
FROM (
SELECT ('"' || table_schema || '"."' || table_name || '"') AS table_name
FROM information_schema.tables
) AS all_tables
ORDER BY total_size DESC
) AS pretty_sizes

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原文链接：https://codingdict.com/

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