SSIS OLE DB Source Editor Data Access Mode: "SQL command" vs "Table or view"
I will make a small experiment. i will use SQL profiler to see what is going in the background while using an OLEDB Source in the two cases:

I have a Table named dbo.Table_1 that contains 3 columns (ID,name,department)

I used SQL profiler to Tune the database containing this Table and i used the 2 access mode, below the results:

Table or View - selecting only ID column

The profiler shows that the following command is executed

SELECT * FROM [dbo].[Table_1]


Even if you only select one column, the OLEDB Source reads all data then filters columns after reading them all.



SQL COMMAND

The profiler shows that the following command is executed

SELECT [ID] FROM [dbo].[Table_1]






Recently I published an article that contains more details, you can check it on the following link:


SQLShack - SSIS OLE DB Source: SQL Command vs Table or View