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From "Eric Evans (JIRA)" <j...@apache.org>
Subject [jira] Commented: (CASSANDRA-1704) CQL reads (aka SELECT)
Date Thu, 04 Nov 2010 21:20:43 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-1704?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12928360#action_12928360
] 

Eric Evans commented on CASSANDRA-1704:
---------------------------------------

Still chewing this over, but one reason this seems (somewhat )strange to me is that <COLUMNS>
here is both of "a list of columns to include in the result" (like in an RDBMS), and "the
query predicate" (or a portion of it anyway). I know that in a very real way those are kind
of one and the same, but the SQL databases people are familiar with all have schema and the
column names are identifiers. It's not just syntactically different, it's semantically different
as well, and I wonder if this isn't going to set people up for misunderstandings.

Also, I'm not clear on whether you intended the <EXPRESSION> portion to remain the same;
you chose a different syntax (less-SQL FWIW) to specifiy ranges and sets of columns than what
I used in <EXPRESSION>.

> CQL reads (aka SELECT)
> ----------------------
>
>                 Key: CASSANDRA-1704
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1704
>             Project: Cassandra
>          Issue Type: Sub-task
>          Components: API
>    Affects Versions: 0.8
>            Reporter: Eric Evans
>            Priority: Minor
>             Fix For: 0.8
>
>   Original Estimate: 0h
>  Remaining Estimate: 0h
>
> Data access specification and implementation for CQL.  
> This corresponds to the following RPC methods:
> * get()
> * get_slice()
> * get_count()
> * multiget_slice()
> * multiget_count()
> * get_range_slices()
> * get_indexed_slices()
> The initial check-in to trunk/ uses a syntax that looks like:
> {code:SQL}
> SELECT (FROM)? <CF> [USING CONSISTENCY.<LVL>] WHERE <EXPRESSION> [ROWLIMIT
X] [COLLIMIT Y] [ASC|DESC]
> {code}
> Where:
> * <CF> is the column family name.
> * <EXPRESSION> consists of relations chained by the AND keyword.
> * <LVL> corresponds to one of the enum values in the RPC interface(s).
> What is still undone:
> * Support for indexes
> * Counts
> * Complete test coverage
> And of course, all of this is still very much open to further discussion.

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