How do I easily find IDENTITY columns in danger of overflowing? - sql-server

Question

My database is getting old, and one of my biggest INT IDENTITY columns has a value around 1.3 billion. This will overflow around 2.1 billion. I plan on increasing it's size, but I don't want to do it too soon because of the number of records in the database. I may replace my database hardware before I increase the column size, which could offset any performance problems this could cause. I also want to keep an eye on all the other columns in my databases that are more than 50% full. It's a lot of tables, and checking each one manually is not practical.
This is how I am getting the value now (I know the value returned may be slightly out of date, but it's good enough for my purposes):
PRINT IDENT_CURRENT('MyDatabase.dbo.MyTable')
Can I use the INFORMATION_SCHEMA to get this information?

Answer 1

You can consult the sys.identity_columns system catalog view:
SELECT
name,
seed_value, increment_value, last_value
FROM sys.identity_columns
This gives you the name, seed, increment and last value for each column. The view also contains the data type, so you can easily figure out which identity columns might be running out of numbers soonish...

Answer 2

I created a stored procedure to solve this problem. It uses the INFORMATION_SCHEMA to find the IDENTITY columns, and then uses IDENT_CURRENT and the column's DATA_TYPE to calculate the percent full. Specify the database as the first parameter, and then optionally the minimum percent and data type.
EXEC master.dbo.CheckIdentityColumns 'MyDatabase' --all
EXEC master.dbo.CheckIdentityColumns 'MyDatabase', 50 --columns 50% full or greater
EXEC master.dbo.CheckIdentityColumns 'MyDatabase', 50, 'int' --only int columns
Example output:
Table Column Type Percent Full Remaining
------------------------- ------------------ ------- ------------ ---------------
MyDatabase.dbo.Table1 Table1ID int 9 1,937,868,393
MyDatabase.dbo.Table2 Table2ID int 5 2,019,944,894
MyDatabase.dbo.Table3 Table3ID int 9 1,943,793,775
I created a reminder to check all my databases once per month, and I log this information in a spreadsheet.
CheckIdentityColumns Procedure
USE master
GO
CREATE PROCEDURE dbo.CheckIdentityColumns
(
#Database AS NVARCHAR(128),
#PercentFull AS TINYINT = 0,
#Type AS VARCHAR(8) = NULL
)
AS
--this procedure assumes you are not using negative numbers in your identity columns
DECLARE #Sql NVARCHAR(3000)
SET #Sql =
'USE ' + #Database + '
SELECT
[Column].TABLE_CATALOG + ''.'' +
[Column].TABLE_SCHEMA + ''.'' +
[Table].TABLE_NAME AS [Table],
[Column].COLUMN_NAME AS [Column],
[Column].DATA_TYPE AS [Type],
CAST((
CASE LOWER([Column].DATA_TYPE)
WHEN ''tinyint''
THEN (IDENT_CURRENT([Table].TABLE_NAME) / 255)
WHEN ''smallint''
THEN (IDENT_CURRENT([Table].TABLE_NAME) / 32767)
WHEN ''int''
THEN (IDENT_CURRENT([Table].TABLE_NAME) / 2147483647)
WHEN ''bigint''
THEN (IDENT_CURRENT([Table].TABLE_NAME) / 9223372036854775807)
WHEN ''decimal''
THEN (IDENT_CURRENT([Table].TABLE_NAME) / (([Column].NUMERIC_PRECISION * 10) - 1))
END * 100) AS INT) AS [Percent Full],
REPLACE(CONVERT(VARCHAR(19), CAST(
CASE LOWER([Column].DATA_TYPE)
WHEN ''tinyint''
THEN (255 - IDENT_CURRENT([Table].TABLE_NAME))
WHEN ''smallint''
THEN (32767 - IDENT_CURRENT([Table].TABLE_NAME))
WHEN ''int''
THEN (2147483647 - IDENT_CURRENT([Table].TABLE_NAME))
WHEN ''bigint''
THEN (9223372036854775807 - IDENT_CURRENT([Table].TABLE_NAME))
WHEN ''decimal''
THEN ((([Column].NUMERIC_PRECISION * 10) - 1) - IDENT_CURRENT([Table].TABLE_NAME))
END
AS MONEY) , 1), ''.00'', '''') AS Remaining
FROM
INFORMATION_SCHEMA.COLUMNS AS [Column]
INNER JOIN
INFORMATION_SCHEMA.TABLES AS [Table]
ON [Table].TABLE_NAME = [Column].TABLE_NAME
WHERE
COLUMNPROPERTY(
OBJECT_ID([Column].TABLE_NAME),
[Column].COLUMN_NAME, ''IsIdentity'') = 1 --true
AND [Table].TABLE_TYPE = ''Base Table''
AND [Table].TABLE_NAME NOT LIKE ''dt%''
AND [Table].TABLE_NAME NOT LIKE ''MS%''
AND [Table].TABLE_NAME NOT LIKE ''syncobj_%''
AND CAST(
(
CASE LOWER([Column].DATA_TYPE)
WHEN ''tinyint''
THEN (IDENT_CURRENT([Table].TABLE_NAME) / 255)
WHEN ''smallint''
THEN (IDENT_CURRENT([Table].TABLE_NAME) / 32767)
WHEN ''int''
THEN (IDENT_CURRENT([Table].TABLE_NAME) / 2147483647)
WHEN ''bigint''
THEN (IDENT_CURRENT([Table].TABLE_NAME) / 9223372036854775807)
WHEN ''decimal''
THEN (IDENT_CURRENT([Table].TABLE_NAME) / (([Column].NUMERIC_PRECISION * 10) - 1))
END * 100
) AS INT) >= ' + CAST(#PercentFull AS VARCHAR(4))
IF (#Type IS NOT NULL)
SET #Sql = #Sql + 'AND LOWER([Column].DATA_TYPE) = ''' + LOWER(#Type) + ''''
SET #Sql = #Sql + '
ORDER BY
[Column].TABLE_CATALOG + ''.'' +
[Column].TABLE_SCHEMA + ''.'' +
[Table].TABLE_NAME,
[Column].COLUMN_NAME'
EXECUTE sp_executesql #Sql
GO

Answer 3

Keith Walton has a very comprehensive query that is very good. Here's a little simpler one that is based on the assumption that the identity columns are all integers:
SELECT sys.tables.name AS [Table Name],
last_value AS [Last Value],
MAX_LENGTH,
CAST(cast(last_value as int) / 2147483647.0 * 100.0 AS DECIMAL(5,2))
AS [Percentage of ID's Used],
2147483647 - cast(last_value as int) AS Remaining
FROM sys.identity_columns
INNER JOIN sys.tables
ON sys.identity_columns.object_id = sys.tables.object_id
ORDER BY last_value DESC
The results will look like this:
Table Name Last Value MAX_LENGTH Percentage of ID's Used Remaining
My_Table 49181800 4 2.29 2098301847
Checking Integer Identity Columns

Answer 4

While crafting a solution for this problem, we found this thread both informative and interesting (we also wrote a detailed post about this and described how our tool works).
In our solution we're querying the information_schema to acquire a list of
all columns. Then we wrote a program that would go through each of them and compute the maximum and minimum (we account for both overflow and underflow).
SELECT
b.COLUMN_NAME,
b.COLUMN_TYPE,
b.DATA_TYPE,
b.signed,
a.TABLE_NAME,
a.TABLE_SCHEMA
FROM (
-- get all tables
SELECT
TABLE_NAME, TABLE_SCHEMA
FROM information_schema.tables
WHERE
TABLE_TYPE IN ('BASE TABLE', 'VIEW') AND
TABLE_SCHEMA NOT IN ('mysql', 'performance_schema')
) a
JOIN (
-- get information about columns types
SELECT
TABLE_NAME,
COLUMN_NAME,
COLUMN_TYPE,
TABLE_SCHEMA,
DATA_TYPE,
(!(LOWER(COLUMN_TYPE) REGEXP '.*unsigned.*')) AS signed
FROM information_schema.columns
) b ON a.TABLE_NAME = b.TABLE_NAME AND a.TABLE_SCHEMA = b.TABLE_SCHEMA
ORDER BY a.TABLE_SCHEMA DESC;