[jira] [Comment Edited] (ORC-362) String direct length streams gets some values even if data is null

["Owen O'Malley (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ORC-362?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16481338#comment-16481338 ] 

Owen O'Malley edited comment on ORC-362 at 5/18/18 11:34 PM:
-------------------------------------------------------------

The "78,16,0,541,0,11" for an uncompressed file with direct encoded string, which I assume this is:

{code}
present:
   bytes: 78
   byte rle: 16
   bit: 0
data:
  bytes: 541
length:
  bytes: 0
  int rle: 11
{code}

Since the previous entry has 2 elements, it makes sense that it moved up from 9 to 11. The 11 is the number of items and not a number of bytes, so I'd guess the 13 bytes is right.


was (Author: owen.omalley):
The "78,16,0,541,0,11" for an uncompressed file with direct encoded string, which I assume this is:

present:
   bytes: 78
   byte rle: 16
   bit: 0
data:
  bytes: 541
length:
  bytes: 0
  int rle: 11

Since the previous entry has 2 elements, it makes sense that it moved up from 9 to 11. The 11 is the number of items and not a number of bytes, so I'd guess the 13 bytes is right.

> String direct length streams gets some values even if data is null
> ------------------------------------------------------------------
>
>                 Key: ORC-362
>                 URL: https://issues.apache.org/jira/browse/ORC-362
>             Project: ORC
>          Issue Type: Bug
>    Affects Versions: 1.4.3
>            Reporter: Prasanth Jayachandran
>            Priority: Major
>
> Observed this in one of the orc files recently.
> Looking at the orcfiledump (compression is NONE) something looks odd
> {code:java}
>     Stream: column 2 section PRESENT start: 13976 length 80
>     Stream: column 2 section DATA start: 14056 length 541
>     Stream: column 2 section LENGTH start: 14597 length 13
> ..
> ..
> ..
>     Row group indices for column 2:
>       Entry 0: count: 4 hasNull: true min: a max: z sum: 157 positions: 0,0,0,0,0,0
>       Entry 1: count: 5 hasNull: true min: a max: z sum: 314 positions: 26,111,0,157,0,4
>       Entry 2: count: 2 hasNull: true min: a max: z sum: 70 positions: 52,62,0,471,0,9
>       Entry 3: count: 0 hasNull: true positions: 78,16,0,541,0,11
> {code}
> If we look at Entry 3 (last entry) and related the stream positions, last entry is all nulls, the corresponding data stream ended at 541 offset (which is same as length). Data stream looks correct. But now if we look at length stream, the position is recorded as 11 in last entry but the length is actually 13 (this last 2 bytes is not expected). If there is no data the length stream is supposedly not record anything. If the data is null, only isPresent stream is expected to have an entry. Looks like orc writer is writing entries to length stream even if data is null (probably recording 0 lengths).



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