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From "Vladimir Ozerov (JIRA)" <j...@apache.org>
Subject [jira] [Created] (IGNITE-6383) SQL: review date/time format
Date Thu, 14 Sep 2017 14:33:00 GMT
Vladimir Ozerov created IGNITE-6383:
---------------------------------------

             Summary: SQL: review date/time format
                 Key: IGNITE-6383
                 URL: https://issues.apache.org/jira/browse/IGNITE-6383
             Project: Ignite
          Issue Type: Task
          Components: sql
    Affects Versions: 2.1
            Reporter: Vladimir Ozerov


Currently Ignite stores date as {{long}} and timestamp as {{long + int}}. This is rather compact
form, however it is extremely inefficient for SQL operations requirind date parts, such as
{{DAYOFF(...)}}. Moreover, it require costly conversions between {{long}} and {{java.util.Date}}.

Probably we should review our date-time format. E.g. this is how Oracle format looks like
(thanks to [~sergey.puchnin@gmail.com]):
{code}
timestamp '2015-07-31 08:55:06.157047'
Typ=180 Len=11: 120,115,7,31,9,56,7,9,92,88,216
Century: 120-100 = 20 centuries
Year : 115-100 = 15 year in the 20th century
Month: 7
Day:31
Hours: 9-1 =8
minutes: 56 -1 = 55
Seconds: 07 -1 = 06
Fractions: 09,92,88,216 (dec) -> 09,5C,58,D8 (hex) = 0x095C58D8 -> 157047000 -> 0.157047
{code}



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