Inserts and New Parquet Files

05-03-25

Every time you insert individual rows into a Fabric warehouse table, the engine generates a new Parquet file because the files are immutable (they can’t change). So, it's best to batch these operations. In the example below, option two creates three Parquet files.

/*Option 1*/
INSERT INTO dbo.Table1 (Column1, Column2)
VALUES (1,'red'), (2,'green'),(3,'yellow');

/*Option 2*/
INSERT INTO dbo.Table1 (Column1, Column2)
VALUES (1,'red');
INSERT INTO dbo.Table1 (Column1, Column2)
VALUES (2,'green');
INSERT INTO dbo.Table1 (Column1, Column2)
VALUES (3,'yellow');

However, performing trickle inserts isn't a good approach for loading data into a warehouse.