sql查询数据库表大小

SELECT 
    table_name AS `Table`,
    round(((data_length + index_length) / 1024 / 1024), 2) `Size in MB`
FROM 
    information_schema.TABLES 
WHERE 
    table_schema = 'your_database_name' AND 
    table_name = 'your_table_name';

SELECT 
    relname AS "Table",
    pg_size_pretty(pg_total_relation_size(relid)) AS "Size"
FROM 
    pg_class c
JOIN 
    pg_namespace n ON n.oid = c.relnamespace
WHERE 
    n.nspname = 'your_schema_name' AND 
    relname = 'your_table_name';

SELECT 
    t.NAME AS TableName,
    s.Name AS SchemaName,
    p.rows AS RowCounts,
    SUM(a.total_pages) * 8 / 1024 AS TotalSpaceMB,
    SUM(a.used_pages) * 8 / 1024 AS UsedSpaceMB,
    (SUM(a.total_pages) - SUM(a.used_pages)) * 8 / 1024 AS UnusedSpaceMB
FROM 
    sys.tables t
INNER JOIN      
    sys.indexes i ON t.OBJECT_ID = i.object_id
INNER JOIN 
    sys.partitions p ON i.object_id = p.OBJECT_ID AND i.index_id = p.index_id
INNER JOIN 
    sys.allocation_units a ON p.partition_id = a.container_id
LEFT OUTER JOIN 
    sys.schemas s ON t.schema_id = s.schema_id
WHERE 
    t.NAME NOT LIKE 'dt%' AND 
    t.is_ms_shipped = 0 AND 
    s.Name = 'your_schema_name'
GROUP BY 
    t.Name, s.Name, p.Rows
ORDER BY 
    TotalSpaceMB DESC, t.Name;