[HIVE-5527] Use of localtime in vectorized Timestamp arithmetic results in data corruption (results depends on localtime)

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Assignee: Unassigned
• Reporter: Remus Rusanu
• Created: 12/Oct/13 15:07
• Updated: 14/Oct/13 14:40

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.