Tuesday 30 April 2019

Finding databases with biggest tables in SQL Server

I created a T-SQL script today for use with SQL Server that will list the tables that have most rows for SQL Server, able to loop through all databases.

DECLARE @currentDB AS VARCHAR(100)
DECLARE @mrsdb_sqlscript AS NVARCHAR(500)
DECLARE db_cursor CURSOR FOR 
SELECT name from sys.databases where state_desc <> 'offline' and name not in ('master', 'tempdb', 'model', 'msdb') order by name 
DROP TABLE IF EXISTS #largestTables 
CREATE TABLE #largestTables (
 DatabaseName VARCHAR(100),
 SchemaName VARCHAR(200), 
 TableName VARCHAR(200), 
 TotalRowCount INT 
)

OPEN db_cursor 
FETCH NEXT from db_cursor into @currentDB 

WHILE @@FETCH_STATUS = 0 
BEGIN
 SET @mrsdb_sqlscript = N'INSERT INTO #largestTables 
  SELECT ''' + @currentDB + ''' , SCHEMA_NAME(schema_id) AS [SchemaName],
 [Tables].name AS [TableName],
 SUM([Partitions].[rows]) AS [TotalRowCount]
 FROM ' + @currentDB + '.sys.tables AS [Tables]
 JOIN ' + @currentDB + '.sys.partitions AS [Partitions]
 ON [Tables].[object_id] = [Partitions].[object_id]
 AND [Partitions].index_id IN ( 0, 1 )
 GROUP BY SCHEMA_NAME(schema_id), [Tables].name';

 PRINT 'Looking for largest table in the following DB: ' + @currentDB 
 exec sp_executesql @mrsdb_sqlscript 

 FETCH NEXT FROM db_cursor into @currentDB
END

CLOSE db_cursor 
DEALLOCATE db_cursor 

SELECT TOP 100 * FROM #largestTables 
ORDER BY TotalRowCount DESC, Schemaname ASC


The SQL script above will use a temporary table variable and database cursor and loop through all databases, executing a SQL script that will insert data into a temporary table variable and after the cursor has looped through its dataset, the result in the temporary table variable is presented to the DBA monitoring. Use it to spot where you have much data in your databases of the data base server you are working with!