Add warning regarding quoted identifiers in CQL doc
Project: http://git-wip-us.apache.org/repos/asf/cassandra/repo Commit: http://git-wip-us.apache.org/repos/asf/cassandra/commit/79b94923 Tree: http://git-wip-us.apache.org/repos/asf/cassandra/tree/79b94923 Diff: http://git-wip-us.apache.org/repos/asf/cassandra/diff/79b94923 Branch: refs/heads/cassandra-3.0 Commit: 79b9492363d60863c717a9dfe4ce8c1769071c85 Parents: 1b59357 Author: Sylvain Lebresne <sylv...@datastax.com> Authored: Mon Jan 18 11:27:24 2016 +0100 Committer: Sylvain Lebresne <sylv...@datastax.com> Committed: Mon Jan 18 11:27:24 2016 +0100 ---------------------------------------------------------------------- doc/cql3/CQL.textile | 2 ++ 1 file changed, 2 insertions(+) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/cassandra/blob/79b94923/doc/cql3/CQL.textile ---------------------------------------------------------------------- diff --git a/doc/cql3/CQL.textile b/doc/cql3/CQL.textile index c2ecbd7..2dd96e7 100644 --- a/doc/cql3/CQL.textile +++ b/doc/cql3/CQL.textile @@ -46,6 +46,8 @@ p. Identifiers and (unquoted) keywords are case insensitive. Thus @SELECT@ is th p. There is a second kind of identifiers called _quoted identifiers_ defined by enclosing an arbitrary sequence of characters in double-quotes(@"@). Quoted identifiers are never keywords. Thus @"select"@ is not a reserved keyword and can be used to refer to a column, while @select@ would raise a parse error. Also, contrarily to unquoted identifiers and keywords, quoted identifiers are case sensitive (@"My Quoted Id"@ is _different_ from @"my quoted id"@). A fully lowercase quoted identifier that matches @[a-zA-Z]@@[a-zA-Z0-9_]@@*@ is equivalent to the unquoted identifier obtained by removing the double-quote (so @"myid"@ is equivalent to @myid@ and to @myId@ but different from @"myId"@). Inside a quoted identifier, the double-quote character can be repeated to escape it, so @"foo "" bar"@ is a valid identifier. +p. *Warning*: _quoted identifiers_ allows to declare columns with arbitrary names, and those can sometime clash with specific names used by the server. For instance, when using conditional update, the server will respond with a result-set containing a special result named @"[applied]"@. If you've declared a column with such a name, this could potentially confuse some tools and should be avoided. In general, unquoted identifiers should be preferred but if you use quoted identifiers, it is strongly advised to avoid any name enclosed by squared brackets (like @"[applied]"@) and any name that looks like a function call (like @"f(x)"@). + h3(#constants). Constants CQL defines the following kind of _constants_: strings, integers, floats, booleans, uuids and blobs:
