[jira] Closed: (DERBY-2591) DataDictionaryImpl.getSystemSQLName() may generate duplicates

["Bernt M. Johnsen (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DERBY-2591?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bernt M. Johnsen closed DERBY-2591.
-----------------------------------


> DataDictionaryImpl.getSystemSQLName() may generate duplicates
> -------------------------------------------------------------
>
>                 Key: DERBY-2591
>                 URL: https://issues.apache.org/jira/browse/DERBY-2591
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>            Reporter: Bernt M. Johnsen
>         Assigned To: Bernt M. Johnsen
>             Fix For: 10.3.0.0
>
>         Attachments: DERBY-2591.diff
>
>
> DataDictionaryImpl.getSystemSQLName() may generates names on the form SQLYYMMDDHHMMSSmmN where mm is in 10 milliseconds and N is number to avoid collisions with 10 milliseconds. The name was probably generated this way to fit into the 18 caharcter limit of constraint names in older derby versions. However, if a getSystemSQLName() is called 12 hours after a call on the same date (e.g at 01:00:00 and 13:00:00), which is unlikely but not very unlikely, a duplicate name is generated, since the HH-part is filled by the call
> 				generatedSystemSQLName.append(twoDigits(calendarForLastSystemSQLName.get(Calendar.HOUR)));
> and Calendar.HOUR implementes the pretty stupid idea that there are only 12 hours. It was definitely Calendar.HOUR_OF_DAY which gives you the hour for a 24-hour clock that should have been used. 

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