Details
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Bug
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Status: Open
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Major
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Resolution: Unresolved
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Description
A query like
SELECT ctimestamp2 from alltypesorc WHERE ctimestamp2 > -10669;
returns rows in row mode, but not in vector mode when running in GMT+2 timezone.
I know what causes this, but I don’t know exactly whether is a bug or not.
The reading of the TIMESTAMP types is done in TimeStampTreeReader class,
long ms = (result.vector[result.isRepeating ? 0 : i] + WriterImpl.BASE_TIMESTAMP)
- WriterImpl.MILLIS_PER_SECOND;
long ns = parseNanos(nanoVector.vector[nanoVector.isRepeating ? 0 : i]);
// the rounding error exists because java always rounds up when dividing integers
// -42001/1000 = -42; and -42001 % 1000 = -1 (+ 1000)
// to get the correct value we need
// (-42 - 1)*1000 + 999 = -42001
// (42)*1000 + 1 = 42001
if(ms < 0 && ns != 0) { ms -= 1000; }// Convert millis into nanos and add the nano vector value to it
result.vector[i] = (ms * 1000000) + ns;
As you see this relies on the ORC WriterImpl.BASE_TIMESTAMP, which is declared as:
static final long BASE_TIMESTAMP =
Timestamp.valueOf("2015-01-01 00:00:00").getTime() / MILLIS_PER_SECOND;
On US/Pacific time, this will be 1420099200
On EEST (GMT+2) time is 1420063200
The first row in alltypesorc for ctimestamp2 reads -1420099192 as data[0] and 7005 as nanos[0]. On US/Pacific, with a LONG vector timestamp value of 8875000000. On EEST it ends up with -35992125000000. (Note how the abs(data[0]) value is smaller than the US/Pacific basetime, but bigger than the EEST, so it goes negative on EEST and just cascades to a huge negative number).
The vector filter simply compares this with -10669 (the query WHERE clause) and it qualifies the row on US/Pacific, but fails on EEST.
I’m not sure what the right solution is, the whole of Hive code appears to be riddled with Timezone problems. As a side node, the build-common.xml sets an environment variable TZ to US/Pacific, but this has no effect in running tests on Windows.
But the gist of it is this: in row mode the results are consistent on any time zone. In vector mode the results vary (rows qualify for WHERE clause) depending on the timezone.