SQL SERVER: Identity Column Capacity Report

IdentityColumnCapacityReport.sql

-- ============================================================
-- Identity Column Capacity Report
-- ============================================================
-- Reports on all tables with identity columns that have 100,000
-- or more rows, showing how much ID space remains and when each
-- table is projected to exhaust its identity range.
--
-- For each qualifying table this query provides:
--   - Current identity value and data type maximum
--   - Remaining IDs available before overflow
--   - Average daily insert rate (sampled since last SQL Server
--     service restart via sys.dm_db_index_operational_stats)
--   - Estimated days remaining and projected exhaustion date
--
-- Results are sorted by risk: int columns first (lowest ceiling),
-- then by percentage of ID range already consumed descending.
-- Exhaustion dates beyond ~500 years are suppressed to avoid
-- integer overflow in DATEADD and shown as a year estimate instead.
--
-- Usage:
--   1. Change the USE statement to your target database.
--   2. Run as-is -- all identity tables are auto-discovered.
--   3. Pay close attention to any int columns near exhaustion;
--      consider ALTER TABLE ... ALTER COLUMN to bigint if at risk.
-- ============================================================

USE [YOUR_DB_NAME]; -- ← set this before running
GO

-- Cap days at ~500 years before DATEADD to prevent int overflow
DECLARE @MaxMeaningfulDays INT = 182500;
-- Tables need to have this many rows to be included in the results, to avoid noise from very small tables where insert patterns may not be established
DECLARE @MinRowLimit INT = 100000

SELECT
    s.name + '.' + t.name                              AS table_name,
    ic.name                                             AS identity_column,
    tp.name                                             AS data_type,
    FORMAT(CAST(IDENT_CURRENT(
        '[' + s.name + '].[' + t.name + ']')
    AS BIGINT), 'N0')                                   AS current_value,

    FORMAT(
        CASE tp.name
            WHEN 'tinyint'  THEN 255
            WHEN 'smallint' THEN 32767
            WHEN 'int'      THEN 2147483647
            WHEN 'bigint'   THEN 9223372036854775807
            ELSE 2147483647
        END, 'N0')                                      AS max_allowed_value,

    FORMAT(
        (   CASE tp.name
                WHEN 'tinyint'  THEN 255
                WHEN 'smallint' THEN 32767
                WHEN 'int'      THEN 2147483647
                WHEN 'bigint'   THEN 9223372036854775807
                ELSE 2147483647
            END
            - CAST(IDENT_CURRENT('[' + s.name + '].[' + t.name + ']') AS BIGINT)
        ) / CAST(ic.increment_value AS BIGINT)
    , 'N0')                                             AS remaining_ids,

    CAST(DATEDIFF(DAY, si.sqlserver_start_time, GETDATE()) AS INT)
                                                        AS stats_sample_days,

    CASE
        WHEN ops.leaf_insert_count = 0 THEN 'No insert activity recorded'
        ELSE FORMAT(CEILING(
            ops.leaf_insert_count * 1.0
            / NULLIF(DATEDIFF(DAY, si.sqlserver_start_time, GETDATE()), 0)
        ), 'N0')
    END                                                 AS avg_inserts_per_day,

    CASE
        WHEN ops.leaf_insert_count = 0 THEN 'Cannot estimate'
        WHEN (
            (   CASE tp.name
                    WHEN 'tinyint'  THEN 255
                    WHEN 'smallint' THEN 32767
                    WHEN 'int'      THEN 2147483647
                    WHEN 'bigint'   THEN 9223372036854775807
                    ELSE 2147483647
                END
                - CAST(IDENT_CURRENT('[' + s.name + '].[' + t.name + ']') AS BIGINT)
            ) / CAST(ic.increment_value AS BIGINT)
        ) / NULLIF(ops.leaf_insert_count * 1.0
            / NULLIF(DATEDIFF(DAY, si.sqlserver_start_time, GETDATE()), 0), 0)
            > @MaxMeaningfulDays
        THEN FORMAT(CEILING((
            (   CASE tp.name
                    WHEN 'tinyint'  THEN 255
                    WHEN 'smallint' THEN 32767
                    WHEN 'int'      THEN 2147483647
                    WHEN 'bigint'   THEN 9223372036854775807
                    ELSE 2147483647
                END
                - CAST(IDENT_CURRENT('[' + s.name + '].[' + t.name + ']') AS BIGINT)
            ) / CAST(ic.increment_value AS BIGINT)
        ) / NULLIF(ops.leaf_insert_count * 1.0
            / NULLIF(DATEDIFF(DAY, si.sqlserver_start_time, GETDATE()), 0), 0)
            / 365.25), 'N0')
        ELSE FORMAT(CEILING((
            (   CASE tp.name
                    WHEN 'tinyint'  THEN 255
                    WHEN 'smallint' THEN 32767
                    WHEN 'int'      THEN 2147483647
                    WHEN 'bigint'   THEN 9223372036854775807
                    ELSE 2147483647
                END
                - CAST(IDENT_CURRENT('[' + s.name + '].[' + t.name + ']') AS BIGINT)
            ) / CAST(ic.increment_value AS BIGINT)
        ) / NULLIF(ops.leaf_insert_count * 1.0
            / NULLIF(DATEDIFF(DAY, si.sqlserver_start_time, GETDATE()), 0), 0)
        ), 'N0')
    END                                                 AS estimated_remaining,

    CASE
        WHEN ops.leaf_insert_count = 0 THEN 'N/A'
        WHEN (
            (   CASE tp.name
                    WHEN 'tinyint'  THEN 255
                    WHEN 'smallint' THEN 32767
                    WHEN 'int'      THEN 2147483647
                    WHEN 'bigint'   THEN 9223372036854775807
                    ELSE 2147483647
                END
                - CAST(IDENT_CURRENT('[' + s.name + '].[' + t.name + ']') AS BIGINT)
            ) / CAST(ic.increment_value AS BIGINT)
        ) / NULLIF(ops.leaf_insert_count * 1.0
            / NULLIF(DATEDIFF(DAY, si.sqlserver_start_time, GETDATE()), 0), 0)
            > @MaxMeaningfulDays
        THEN 'Years (> 500 yr range)'
        ELSE 'Days'
    END                                                 AS unit,

    CASE
        WHEN ops.leaf_insert_count = 0 THEN NULL
        WHEN (
            (   CASE tp.name
                    WHEN 'tinyint'  THEN 255
                    WHEN 'smallint' THEN 32767
                    WHEN 'int'      THEN 2147483647
                    WHEN 'bigint'   THEN 9223372036854775807
                    ELSE 2147483647
                END
                - CAST(IDENT_CURRENT('[' + s.name + '].[' + t.name + ']') AS BIGINT)
            ) / CAST(ic.increment_value AS BIGINT)
        ) / NULLIF(ops.leaf_insert_count * 1.0
            / NULLIF(DATEDIFF(DAY, si.sqlserver_start_time, GETDATE()), 0), 0)
            > @MaxMeaningfulDays
        THEN NULL
        ELSE CAST(DATEADD(DAY, CAST(CEILING((
            (   CASE tp.name
                    WHEN 'tinyint'  THEN 255
                    WHEN 'smallint' THEN 32767
                    WHEN 'int'      THEN 2147483647
                    WHEN 'bigint'   THEN 9223372036854775807
                    ELSE 2147483647
                END
                - CAST(IDENT_CURRENT('[' + s.name + '].[' + t.name + ']') AS BIGINT)
            ) / CAST(ic.increment_value AS BIGINT)
        ) / NULLIF(ops.leaf_insert_count * 1.0
            / NULLIF(DATEDIFF(DAY, si.sqlserver_start_time, GETDATE()), 0), 0)
        ) AS INT), GETDATE()) AS DATE)
    END                                                 AS projected_exhaustion_date

FROM sys.identity_columns ic
JOIN sys.tables t  ON ic.object_id = t.object_id
JOIN sys.schemas s ON t.schema_id  = s.schema_id
JOIN sys.types tp  ON ic.user_type_id = tp.user_type_id
CROSS JOIN sys.dm_os_sys_info si
JOIN (
    SELECT
        t2.object_id,
        SUM(ops.leaf_insert_count) AS leaf_insert_count
    FROM sys.tables t2
    JOIN sys.identity_columns ic2 ON t2.object_id = ic2.object_id
    CROSS APPLY sys.dm_db_index_operational_stats(DB_ID(), t2.object_id, NULL, NULL) ops
    GROUP BY t2.object_id
) ops ON ops.object_id = t.object_id

JOIN (
    SELECT object_id, SUM(row_count) AS row_count
    FROM sys.dm_db_partition_stats
    WHERE index_id IN (0, 1) -- heap or clustered index only
    GROUP BY object_id
    HAVING SUM(row_count) >= @MinRowLimit
) rc ON rc.object_id = t.object_id

ORDER BY
    -- Sort tables with int columns and higher usage % to the top as they are most at risk
    CASE tp.name WHEN 'int' THEN 0 ELSE 1 END,
    CAST(IDENT_CURRENT('[' + s.name + '].[' + t.name + ']') AS BIGINT) * 1.0
    / CASE tp.name
        WHEN 'tinyint'  THEN 255
        WHEN 'smallint' THEN 32767
        WHEN 'int'      THEN 2147483647
        WHEN 'bigint'   THEN 9223372036854775807
        ELSE 2147483647
      END DESC;