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Posted to dev@ignite.apache.org by "Vladimir Ozerov (JIRA)" <ji...@apache.org> on 2017/09/14 14:33:00 UTC
[jira] [Created] (IGNITE-6383) SQL: review date/time format
Vladimir Ozerov created IGNITE-6383:
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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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