[HADOOP-9713] FSDataInputStream.readFully doesn't work on filesystems without seek -even when the offset==getPos

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.1.0-beta, 1.3.0, 3.0.0-alpha1
• Component/s: fs
• Assignee: Mikhail Pryakhin
• Reporter: Steve Loughran
• Created: 09/Jul/13 17:11
• Updated: 05/May/20 13:57

Description

FSDataInputStream.readFully(offset,data) doesn't work even if the offset==the current location -because it always seeks to the offset and seeks back. No seek => Exception.

We could optimise FSDataInputStream.readFully(offset,data) to eliminate the seeks on these operations -which would have tangible benefits for those filesystems where seek is expensive (remote blobstores). It would also let you use readFully against filesystems without seeks, provided you are only reading from the current location.