[teiid-issues] [JBoss JIRA] (TEIID-5290) NOW() function returns the same value for each call in BEGIN...END block

[Steven Hawkins (JIRA)]

    [ https://issues.jboss.org/browse/TEIID-5290?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13548601#comment-13548601 ] 

Steven Hawkins commented on TEIID-5290:
---------------------------------------

On 2 - prior to TEIID-5204 the function was non-deterministic, but planned as if it were command deterministic.  That was not desirable as the behavior was not consistent, but most of the time it meant that a single value per user command was used.  Post TEIID-5204 it's fully command deterministic.  Thinking about this more it's probably better to leave it that way as that is the most consistent with previous planning.  So I'm leading instead toward adding a new function, such as clock_timestamp.

> NOW() function returns the same value for each call in BEGIN...END block
> ------------------------------------------------------------------------
>
>                 Key: TEIID-5290
>                 URL: https://issues.jboss.org/browse/TEIID-5290
>             Project: Teiid
>          Issue Type: Bug
>          Components: Query Engine
>    Affects Versions: 10.1
>         Environment: teiid-10.1.0 on WildFly Full 11.0.0.Final (WildFly Core 3.0.8.Final)
>            Reporter: dalex dalex
>            Assignee: Steven Hawkins
>             Fix For: 10.2
>
>
> Run the following queries:
> {code:sql}
> BEGIN
> 	declare timestamp ts1 = select now();
> 	DECLARE integer c = 20000;
> 	WHILE (c > 0) 
> 		BEGIN
> 			c= c-1; 
> 		END
> 	declare timestamp ts2 = select now();
> 	select ts1, ts2;
> END ;;
> {code}
> and
> {code:sql}
> BEGIN
> 	DECLARE integer c = 20000;
> 	create local temporary table #tem(ts timestamp);
> 	WHILE (c > 0) 
> 		BEGIN
> 			INSERT INTO #tem VALUES((select NOW()));
> 			c= c-1; 
> 		END 
> 	select * from #tem;
> END ;;
> {code}
> NOW() function returns the same value for each call in BEGIN...END block and it doesn't matter if it is atomic or not.



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