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Posted to commits@cassandra.apache.org by sl...@apache.org on 2014/02/05 16:37:07 UTC
[4/4] git commit: Merge branch 'cassandra-1.2' into cassandra-2.0
Merge branch 'cassandra-1.2' into cassandra-2.0
Conflicts:
CHANGES.txt
NEWS.txt
build.xml
debian/changelog
Project: http://git-wip-us.apache.org/repos/asf/cassandra/repo
Commit: http://git-wip-us.apache.org/repos/asf/cassandra/commit/49bb972c
Tree: http://git-wip-us.apache.org/repos/asf/cassandra/tree/49bb972c
Diff: http://git-wip-us.apache.org/repos/asf/cassandra/diff/49bb972c
Branch: refs/heads/cassandra-2.0
Commit: 49bb972c6f79c6717b4750488bdcb035bb770784
Parents: 29670eb 16efdf4
Author: Sylvain Lebresne <sy...@datastax.com>
Authored: Wed Feb 5 16:36:50 2014 +0100
Committer: Sylvain Lebresne <sy...@datastax.com>
Committed: Wed Feb 5 16:36:50 2014 +0100
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doc/cql3/CQL.textile | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
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http://git-wip-us.apache.org/repos/asf/cassandra/blob/49bb972c/doc/cql3/CQL.textile
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diff --cc doc/cql3/CQL.textile
index cf73708,b18ce22..f82fc19
--- a/doc/cql3/CQL.textile
+++ b/doc/cql3/CQL.textile
@@@ -459,11 -443,9 +457,11 @@@ INSERT INTO NerdMovies (movie, director
VALUES ('Serenity', 'Joss Whedon', 'Nathan Fillion', 2005)
USING TTL 86400;
- The @INSERT@ statement writes one or more columns for a given row in a table. Note that since a row is identified by its @PRIMARY KEY@, the columns that compose it must be specified. Also, since a row only exists when it contains one value for a column not part of the @PRIMARY KEY@, one such value must be specified too.
+ The @INSERT@ statement writes one or more columns for a given row in a table. Note that since a row is identified by its @PRIMARY KEY@, at least the columns composing it must be specified.
-Note that unlike in SQL, @INSERT@ does not check the prior existence of the row: the row is created if none existed before, and updated otherwise. Furthermore, there is no mean to know which of creation or update happened. In fact, the semantic of @INSERT@ and @UPDATE@ are identical.
+Note that unlike in SQL, @INSERT@ does not check the prior existence of the row by default: the row is created if none existed before, and updated otherwise. Furthermore, there is no mean to know which of creation or update happened.
+
+It is however possible to use the @IF NOT EXISTS@ condition to only insert if the row does not exist prior to the insertion. But please note that using @IF NOT EXISTS@ will incur a non negligible performance cost (internally, Paxos will be used) so this should be used sparingly.
All updates for an @INSERT@ are applied atomically and in isolation.