Prasanth Jayachandran created ORC-362:
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Summary: 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
Observed this in one of the orc files recently.
Looking at the orcfiledump (compression is NONE) something looks odd
{code}
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: Date Record First Seen at LOGSA max:
Unit Identification Code Assigned to this DoDAAC sum: 157 positions: 0,0,0,0,0,0
Entry 1: count: 5 hasNull: true min: The equipment-type-id of a specific
WEAPON-TYPE (a role name for object-type-id). max: This column should always be
blank. sum: 314 positions: 26,111,0,157,0,4
Entry 2: count: 2 hasNull: true min: This column should always be blank.
max: This column should always be blank. 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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