Disable prefetching of next rowgroup by setting max_buffered_morsels to 1

Dandandan · Dandandan · commit 5df7cb093089 · 2026-03-25T08:25:14.000+01:00
diff --git a/datafusion/datasource/src/file_stream/mod.rs b/datafusion/datasource/src/file_stream/mod.rs
@@ -57,7 +57,7 @@ const DEFAULT_OUTSTANDING_IOS_PER_PARTITION: usize = 2;
 ///
 /// TODO make this a config option
 fn max_buffered_morsels() -> usize {
-    2
+    1
 }
 
 /// Resolve the shared outstanding-I/O budget for one `DataSourceExec`.

Original file line number	Diff line number	Diff line change
`@@ -57,7 +57,7 @@ const DEFAULT_OUTSTANDING_IOS_PER_PARTITION: usize = 2;`
`57`	`57`	`///`
`58`	`58`	`/// TODO make this a config option`
`59`	`59`	`fn max_buffered_morsels() -> usize {`
`60`		`- 2`
	`60`	`+ 1`
`61`	`61`	`}`
`62`	`62`
`63`	`63`	/// Resolve the shared outstanding-I/O budget for one `DataSourceExec`.