Author: mreutegg
Date: Thu Jul 11 13:07:01 2013
New Revision: 1502213
URL: http://svn.apache.org/r1502213
Log:
OAK-893: MongoMK may fail with MicroKernelException under concurrent commits
- Update documentation to reflect recent changes
Modified:
jackrabbit/oak/trunk/doc/mongomk.md
Modified: jackrabbit/oak/trunk/doc/mongomk.md
URL:
http://svn.apache.org/viewvc/jackrabbit/oak/trunk/doc/mongomk.md?rev=1502213&r1=1502212&r2=1502213&view=diff
==============================================================================
--- jackrabbit/oak/trunk/doc/mongomk.md (original)
+++ jackrabbit/oak/trunk/doc/mongomk.md Thu Jul 11 13:07:01 2013
@@ -27,7 +27,7 @@ The basic MongoDB document of a node in
},
"_modified" : NumberLong(274208361),
"_revisions" : {
- "r13f3875b5d1-0-1" : "true"
+ "r13f3875b5d1-0-1" : "c"
}
}
@@ -46,15 +46,16 @@ the revision the node was deleted in.
The sub-document `_lastRev` contains the last revision written to this node by
each cluster node. In the above example the MongoMK cluster node with id `1`
modified the node the last time in revision `r13f3875b5d1-0-1`, when it created
-the node.
+the node. These revisions are only updated for non-branch commits.
The `_modified` field contains a low-resolution timestamp when the node was
last
-modified. The time resolution is five seconds.
+modified. The time resolution is five seconds. This field is also updated when
+a branch commit modifies a node.
The sub-document `_commitRoot` contains commit root depth for the commit in
which
the node was created against the revision.
-Finally, the `_revision` sub-document contains commit information about changes
+Finally, the `_revisions` sub-document contains commit information about
changes
marked with a revision. E.g. the single entry in the above document tells us
that everything marked with revision `r13f3875b5d1-0-1` is committed and
therefore valid. In case the change is done in a branch then the value would
be the
@@ -74,8 +75,8 @@ result in the following document:
},
"_modified" : NumberLong(274208516),
"_revisions" : {
- "r13f3875b5d1-0-1" : "true",
- "r13f38818ab6-0-1" : "true"
+ "r13f3875b5d1-0-1" : "c",
+ "r13f38818ab6-0-1" : "c"
},
"prop" : {
"r13f38818ab6-0-1" : "\"foo\""
@@ -85,7 +86,7 @@ result in the following document:
Now the document contains a new sub-document with the name of the new property.
The value of the property is annotated with the revision the property was set.
With each successful commit to this node, a new field is added to the
-`_revision` sub-document. Similarly the `_lastRev` sub-document and `_modified`
+`_revisions` sub-document. Similarly the `_lastRev` sub-document and
`_modified`
field are updated.
After the node is deleted the document looks like this:
@@ -101,9 +102,9 @@ After the node is deleted the document l
},
"_modified" : NumberLong(274208539),
"_revisions" : {
- "r13f3875b5d1-0-1" : "true",
- "r13f38818ab6-0-1" : "true",
- "r13f38835063-2-1" : "true"
+ "r13f3875b5d1-0-1" : "c",
+ "r13f38818ab6-0-1" : "c",
+ "r13f38835063-2-1" : "c"
},
"prop" : {
"r13f38818ab6-0-1" : "\"foo\""
@@ -124,7 +125,7 @@ Revision Model
Background Operations
---------------------
-Each MongoMK instance connecting to same database in Mongo server performs
certain backgroun task
+Each MongoMK instance connecting to same database in Mongo server performs
certain background task.
### Renew Cluster Id Lease
@@ -133,7 +134,7 @@ Each MongoMK instance connecting to same
While performing commits there are certain nodes which are modified but do not
become part
of commit. For example when a node under /a/b/c is updated then the `_lastRev`
property also
needs to be updated to the commit revision. Such changes are accumulated and
flushed periodically
-through a asynch job
+through a asynch job.
### Background Reads
