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Posted to dev@hive.apache.org by "Remus Rusanu (JIRA)" <ji...@apache.org> on 2013/10/14 16:41:43 UTC
[jira] [Updated] (HIVE-5527) Use of localtime in vectorized
Timestamp arithmetic results in data corruption (results depends on
localtime)
[ https://issues.apache.org/jira/browse/HIVE-5527?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Remus Rusanu updated HIVE-5527:
-------------------------------
Summary: Use of localtime in vectorized Timestamp arithmetic results in data corruption (results depends on localtime) (was: Use of localtime Calendar in vectorized Timestamp arithmetic results in data corruption (depends on localtime))
> Use of localtime in vectorized Timestamp arithmetic results in data corruption (results depends on localtime)
> -------------------------------------------------------------------------------------------------------------
>
> Key: HIVE-5527
> URL: https://issues.apache.org/jira/browse/HIVE-5527
> Project: Hive
> Issue Type: Bug
> Reporter: Remus Rusanu
>
> 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.
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