Is it a known bug? Any workaround?

Added a vertex

gremlin> v=graph.addVertex();

==>v[204804096]

gremlin> v.property("name", "name1");

==>vp[name->name1]

gremlin> v.property("p1", "v");

==>vp[p1->v]

gremlin> v.property("p2", "v");

==>vp[p2->v]

gremlin> graph.tx().commit();

==>null

gremlin> g.V(204804096).properties();

==>vp[name->name1]

==>vp[p1->v]

==>vp[p2->v]

gremlin> graph.tx().commit();

==>null

Updated propeties p1 and p2 to value x

gremlin> v=g.V().has("name", "name1").next();

==>v[204804096]

gremlin> v.property("p1", "x");

==>vp[p1->x]

gremlin> v.property("p2", "x")

==>vp[p2->x]

gremlin> graph.tx().commit();

==>null

gremlin> g.V(204804096).properties();

==>vp[name->name1]

==>vp[p1->x]

==>vp[p2->x]

Updated propeties p1 and p2 to value y and in the same transaction the properties are removed

gremlin> v=g.V().has("name", "name1").next();

==>v[204804096]

gremlin> v.property("p1", "y");

==>vp[p1->y]

gremlin> v.property("p2", "y");

==>vp[p2->y]

gremlin> v.property("p1").remove()

==>null

gremlin> v.property("p2").remove()

==>null

gremlin> g.V(204804096).properties();

==>vp[name->name1]

==>vp[p1->x]

==>vp[p2->x]

gremlin> graph.tx().commit();

==>null

gremlin> g.V(204804280).properties();

==>vp[name->v1]

==>vp[p1->x]

==>vp[p2->x]

Properties p1 and p2 are not removed. Their values are set to previous value of "x".

I think this is a bug. You may raise an issue on GitHub about that.

Basically, when we updated a property and then removing this property in the same transaction, JanusGraph thinks that the property is new and remove it only from added relations inside the current transaction (i.e. remove the updated version of the property without marking it for deletion during the transaction closure). I think, we should mark the property as a modified property to resolve the issue.

As a temporary workaround, you may call "remove" 2 times for modified properties. In such case, the property will be marked for deletion and will be removed during the commit operation.

I.e. call  next 4 operations to remove 2 properties:

v.property("p1").remove()
v.property("p1").remove()

v.property("p2").remove()
v.property("p2").remove()

After the issue is fixed, you will need only 1 "remove" call per each modified property. Please open the issue on GitHub about that.

Thank you,

Oleksandr

On Tuesday, February 18, 2020 at 3:41:54 PM UTC-8, Bharat Dighe wrote:

Is it a known bug? Any workaround?

Added a vertex

gremlin> v=graph.addVertex();

==>v[204804096]

gremlin> v.property("name", "name1");

==>vp[name->name1]

gremlin> v.property("p1", "v");

==>vp[p1->v]

gremlin> v.property("p2", "v");

==>vp[p2->v]

gremlin> graph.tx().commit();

==>null

gremlin> g.V(204804096).properties();

==>vp[name->name1]

==>vp[p1->v]

==>vp[p2->v]

gremlin> graph.tx().commit();

==>null

Updated propeties p1 and p2 to value x

gremlin> v=g.V().has("name", "name1").next();

==>v[204804096]

gremlin> v.property("p1", "x");

==>vp[p1->x]

gremlin> v.property("p2", "x")

==>vp[p2->x]

gremlin> graph.tx().commit();

==>null

gremlin> g.V(204804096).properties();

==>vp[name->name1]

==>vp[p1->x]

==>vp[p2->x]

Updated propeties p1 and p2 to value y and in the same transaction the properties are removed

gremlin> v=g.V().has("name", "name1").next();

==>v[204804096]

gremlin> v.property("p1", "y");

==>vp[p1->y]

gremlin> v.property("p2", "y");

==>vp[p2->y]

gremlin> v.property("p1").remove()

==>null

gremlin> v.property("p2").remove()

==>null

gremlin> g.V(204804096).properties();

==>vp[name->name1]

==>vp[p1->x]

==>vp[p2->x]

gremlin> graph.tx().commit();

==>null

gremlin> g.V(204804280).properties();

==>vp[name->v1]

==>vp[p1->x]

==>vp[p2->x]

Properties p1 and p2 are not removed. Their values are set to previous value of "x".

This bug introduced by optimization, when property changed - no one read query will be triggered, data just overwritten blindly, see https://github.com/JanusGraph/janusgraph/blob/100a2ee21351c24eedc0bd9533a49870ab16002a/janusgraph-core/src/main/java/org/janusgraph/graphdb/transaction/StandardJanusGraphTx.java#L796-L808

For fix that we need to read old property from db to mark it deleted

Or rewrite property explicitly

graph=JanusGraphFactory.open("inmemory")
g=graph.traversal()
v=graph.addVertex();
vid=v.id();
v.property("name", "name1");
v.property("p1", "a");
graph.tx().commit();
v=g.V().has("name", "name1").next();
v.property("p1").remove() // remove old property explicitly
v.property("p1", "y");
v.property("p1").remove()
g.V(vid).properties();
graph.tx().commit();
g.V(vid).properties();

четверг, 20 февраля 2020 г., 20:14:12 UTC+3 пользователь Oleksandr Porunov написал:

I think this is a bug. You may raise an issue on GitHub about that.

Basically, when we updated a property and then removing this property in the same transaction, JanusGraph thinks that the property is new and remove it only from added relations inside the current transaction (i.e. remove the updated version of the property without marking it for deletion during the transaction closure). I think, we should mark the property as a modified property to resolve the issue.

As a temporary workaround, you may call "remove" 2 times for modified properties. In such case, the property will be marked for deletion and will be removed during the commit operation.

I.e. call  next 4 operations to remove 2 properties:

v.property("p1").remove()
v.property("p1").remove()

v.property("p2").remove()
v.property("p2").remove()

After the issue is fixed, you will need only 1 "remove" call per each modified property. Please open the issue on GitHub about that.

Thank you,

Oleksandr

On Tuesday, February 18, 2020 at 3:41:54 PM UTC-8, Bharat Dighe wrote:

Is it a known bug? Any workaround?

Added a vertex

gremlin> v=graph.addVertex();

==>v[204804096]

gremlin> v.property("name", "name1");

==>vp[name->name1]

gremlin> v.property("p1", "v");

==>vp[p1->v]

gremlin> v.property("p2", "v");

==>vp[p2->v]

gremlin> graph.tx().commit();

==>null

gremlin> g.V(204804096).properties();

==>vp[name->name1]

==>vp[p1->v]

==>vp[p2->v]

gremlin> graph.tx().commit();

==>null

Updated propeties p1 and p2 to value x

gremlin> v=g.V().has("name", "name1").next();

==>v[204804096]

gremlin> v.property("p1", "x");

==>vp[p1->x]

gremlin> v.property("p2", "x")

==>vp[p2->x]

gremlin> graph.tx().commit();

==>null

gremlin> g.V(204804096).properties();

==>vp[name->name1]

==>vp[p1->x]

==>vp[p2->x]

Updated propeties p1 and p2 to value y and in the same transaction the properties are removed

gremlin> v=g.V().has("name", "name1").next();

==>v[204804096]

gremlin> v.property("p1", "y");

==>vp[p1->y]

gremlin> v.property("p2", "y");

==>vp[p2->y]

gremlin> v.property("p1").remove()

==>null

gremlin> v.property("p2").remove()

==>null

gremlin> g.V(204804096).properties();

==>vp[name->name1]

==>vp[p1->x]

==>vp[p2->x]

gremlin> graph.tx().commit();

==>null

gremlin> g.V(204804280).properties();

==>vp[name->v1]

==>vp[p1->x]

==>vp[p2->x]

Properties p1 and p2 are not removed. Their values are set to previous value of "x".