Reputation: 65248
Where to find the size of SQL Server data types
I am trying to calculate the size of my database. I will have a table with 3 columns (id, int, money) I will have 26 million rows with all columns being occupied. How big will my database be? Also, where can I find the size of all SQL Server data types?
Upvotes: 10
Views: 23324
Answers (4)
Reputation: 760
T-SQL has a function for that: DATALENGTH for all SQL Server versions.
Example:
DECLARE @lat DECIMAL(10, 7) = 3.14151415141514151415;
SELECT @lat, DATALENGTH(@lat);
Result:
3.1415142 and 5 (because DECIMAL(10,7) uses 5 bytes to be stored).
Documentation: https://learn.microsoft.com/en-us/sql/t-sql/functions/datalength-transact-sql?view=sql-server-ver15
For example, I have a table called Applications with these columns: (id VARCHAR(32), debug BIT, connectionString VARCHAR(2048), firebaseKey VARCHAR(4096)). As we know, VARCHAR doesn't allocate all the space (just what you need, so 'A' is 1 byte in VARCHAR).
These queries:
SELECT
SUM(DATALENGTH(id)) AS idSize,
SUM(DATALENGTH(debug)) AS debugSize,
SUM(DATALENGTH(connectionString)) AS connectionStringSize,
SUM(DATALENGTH(firebaseKey)) AS firebaseKeySize
FROM Applications;
SELECT
SUM(
DATALENGTH(id) +
DATALENGTH(debug) +
DATALENGTH(connectionString) +
DATALENGTH(firebaseKey)
) AS totalSize
FROM Applications;
will return my data size (in my case, with my rows, is 8, 2, 366, 4698 (total: 5074). There are 2 rows in that table.
Notice that this does NOT represent the total size of my database (there are pages, descriptors, indexes, etc. involved.)*
MSSQL has internal stored procedures to tell you the exactly size of your database in disk:
EXEC sp_spaceused;for all database;EXEC sp_spaceused N'schema.TableName';for a specific table;EXEC sp_helpdb N'DatabaseName';if you want details from each file.
Upvotes: 2
Reputation: 824
If the table specified in the where clause contains a nvarchar, this query will give you how many characters there are for that column correctly!
This detects if the column is "wide" and essentially divides by 2. More broad than just nvarchar.
SELECT c.name, (CASE WHEN LEFT(ts.name, 1) = 'n' AND ts.[precision] = 0 AND ts.[scale] = 0 THEN c.max_length / ts.[bytes] ELSE c.max_length END) AS [length]
FROM sys.columns AS c
INNER JOIN sys.tables AS t
ON t.object_id = c.object_ID
INNER JOIN
(
SELECT *, (CASE WHEN [bits] = -1 THEN -1 ELSE ([bits] + 7) / 8 END) AS [bytes]
FROM (
SELECT *, (CASE WHEN max_length >= 256 THEN (CASE WHEN LEFT(name, 1) = 'n' AND [precision] = 0 AND [scale] = 0 THEN 16 ELSE 8 END) ELSE max_length END) AS [bits]
FROM sys.types AS iits
) AS its
) AS ts
ON ts.user_type_id = c.user_type_id
WHERE t.name LIKE 'tb_tablename' -- LIKE is case insensitive
Of course, you can just divide max_length on sys.columns by 2 if you know the column is an nvarchar. This is more for discovering table schema in a way that seems better for if new sql data types are introduced in the future. And you so-choose to upgrade to it. Pretty small edge case.
Please edit and correct this answer if you find an edge case where bytes and bits are incorrect.
Details:
-- ([bits] + 7) / 8 means round up
--
-- Proof:
-- o (1 bit + 7 = 8) / 8 = 1 byte used
-- o ((8 + 8 + 1 = 17 bytes) + 7 = 24) / 8 = 3 byes used
-- o ((8 + 8 + 7 = 23 bytes) + 7 = 30) / 8 = 3.75 = integer division removes decimal = 3
SELECT *, (CASE WHEN [bits] = -1 THEN -1 ELSE ([bits] + 7) / 8 END) AS [bytes]
FROM (
SELECT *, (CASE WHEN max_length >= 256 THEN (CASE WHEN LEFT(name, 1) = 'n' AND [precision] = 0 AND [scale] = 0 THEN 16 ELSE 8 END) ELSE max_length END) AS [bits]
FROM sys.types AS its
) AS ts
If someone knows that SQL Server stores the bit and byte sizes for each data type. Or a better way to get sys.columns size, please leave a comment!
Upvotes: 0
Reputation: 11571
Your can use below query :
SELECT * FROM sys.types
result of above query is below :
name system_type_id user_type_id schema_id principal_id max_length precision scale collation_name is_nullable is_user_defined is_assembly_type default_object_id rule_object_id is_table_type
-------------------- -------------- ------------ --------- ------------ ---------- --------- ----- ----------------- ----------- --------------- ---------------- ----------------- -------------- -------------
image 34 34 4 NULL 16 0 0 NULL 1 0 0 0 0 0
text 35 35 4 NULL 16 0 0 Persian_100_CI_AI 1 0 0 0 0 0
uniqueidentifier 36 36 4 NULL 16 0 0 NULL 1 0 0 0 0 0
date 40 40 4 NULL 3 10 0 NULL 1 0 0 0 0 0
time 41 41 4 NULL 5 16 7 NULL 1 0 0 0 0 0
datetime2 42 42 4 NULL 8 27 7 NULL 1 0 0 0 0 0
datetimeoffset 43 43 4 NULL 10 34 7 NULL 1 0 0 0 0 0
tinyint 48 48 4 NULL 1 3 0 NULL 1 0 0 0 0 0
smallint 52 52 4 NULL 2 5 0 NULL 1 0 0 0 0 0
int 56 56 4 NULL 4 10 0 NULL 1 0 0 0 0 0
smalldatetime 58 58 4 NULL 4 16 0 NULL 1 0 0 0 0 0
real 59 59 4 NULL 4 24 0 NULL 1 0 0 0 0 0
money 60 60 4 NULL 8 19 4 NULL 1 0 0 0 0 0
datetime 61 61 4 NULL 8 23 3 NULL 1 0 0 0 0 0
float 62 62 4 NULL 8 53 0 NULL 1 0 0 0 0 0
sql_variant 98 98 4 NULL 8016 0 0 NULL 1 0 0 0 0 0
ntext 99 99 4 NULL 16 0 0 Persian_100_CI_AI 1 0 0 0 0 0
bit 104 104 4 NULL 1 1 0 NULL 1 0 0 0 0 0
decimal 106 106 4 NULL 17 38 38 NULL 1 0 0 0 0 0
numeric 108 108 4 NULL 17 38 38 NULL 1 0 0 0 0 0
smallmoney 122 122 4 NULL 4 10 4 NULL 1 0 0 0 0 0
bigint 127 127 4 NULL 8 19 0 NULL 1 0 0 0 0 0
hierarchyid 240 128 4 NULL 892 0 0 NULL 1 0 1 0 0 0
geometry 240 129 4 NULL -1 0 0 NULL 1 0 1 0 0 0
geography 240 130 4 NULL -1 0 0 NULL 1 0 1 0 0 0
varbinary 165 165 4 NULL 8000 0 0 NULL 1 0 0 0 0 0
varchar 167 167 4 NULL 8000 0 0 Persian_100_CI_AI 1 0 0 0 0 0
binary 173 173 4 NULL 8000 0 0 NULL 1 0 0 0 0 0
char 175 175 4 NULL 8000 0 0 Persian_100_CI_AI 1 0 0 0 0 0
timestamp 189 189 4 NULL 8 0 0 NULL 0 0 0 0 0 0
nvarchar 231 231 4 NULL 8000 0 0 Persian_100_CI_AI 1 0 0 0 0 0
nchar 239 239 4 NULL 8000 0 0 Persian_100_CI_AI 1 0 0 0 0 0
xml 241 241 4 NULL -1 0 0 NULL 1 0 0 0 0 0
sysname 231 256 4 NULL 256 0 0 Persian_100_CI_AI 0 0 0 0 0 0
CalculatedCreditInfo 243 257 9 NULL -1 0 0 NULL 0 1 0 0 0 1
udt_QoutaDetail 243 258 21 NULL -1 0 0 NULL 0 1 0 0 0 1
BeforeUpdate 243 259 22 NULL -1 0 0 NULL 0 1 0 0 0 1
udt_StoreInventory 243 260 26 NULL -1 0 0 NULL 0 1 0 0 0 1
udt_WKFHistory 243 261 32 NULL -1 0 0 NULL 0 1 0 0 0 1
IDTable 243 262 1 NULL -1 0 0 NULL
you can use max_length for size of each data type.
Upvotes: 20
Reputation: 46849
http://msdn.microsoft.com/en-us/library/ms187752.aspx
Money : 8 bytes
int : 4 bytes
id - depends on what you mean.
Upvotes: 0
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