For now, we have to do read after write and do rollback if needed from the application layer as NebulaGraph DB core doesn’t support transactions for now.

Okay. Thanks for the information.

One more query. I'm using GO statement to retrieve 2nd degree vertices and the result set contains vertices mapped with either of the two tags (Tag_A or Tag_B). In such a case, how do I apply filter/condition to print only the vertices of Tag_A type? GO 2 STEPS FROM "123456" OVER * WHERE tags($$)=="Tag_A" YIELD id($$); I tried the above query but couldn't achieve the desired result

Hi. Does Nebula Java client supports batch insert?

Can anyone please confirm if the Nebula Java client supports batch insert? I checked and looks like it is not supported. Wanted to confirm.

Hi team. Do I have an advantage in terms of performance/lookup speed when choosing int64 as VID over string? I've a vertex which stores a domain name in it (The vertex is associated with a tag named "domain" and domain name is one of its properties). In terms of querying, domain name will be used in most of the cases to query a particular vertex. In such a scenario, should I choose domain name as VID (String type) or use hash algorithm such as snowflake (As suggested in the docs) to generate an int64 and use it as VID. Can you please clarify on the query performance part when using int64 over string as VID?

Any plans to provide support for rolling upgrade? Upgrading clusters with zero-downtime is necessary for us.

It can be done for minor version upgrade, eg 3.2.0 to 3.2.1 (will se for 3.3.0 but I suppose it will be the same) which I did few days ago, upgrading cluster node by node without downtime.

Oh okay. Can you please confirm if the support for rolling upgrade (For major version) is in your roadmap? @wey

Hi team. I've got few queries regarding the usage of domains(Instead of hosts IP) in nebula 1. I had setup 3 meta nodes and DNS mapping was made for 3 of the hosts IP to a single domain. When I configured the domain in place of meta-addrs in the conf file, only one of the IPs were mapped as meta and not all three. May I know the reason for this behaviour? 2. In client side, from Java, what is the suggested method to configure graph processes' IPs? As hosts IP may change at times, i thought of having a DNS mapping to the IPs and provide the domains in Java while making connection. Is this method a suggested one? Also, are DNS lookup results cached in the client side and if cached, how frequent they're invalidated and updated in client side? It would be great if you guys share some insights on this matter. Thank you

I’m using IP addresses in config files, because it is at the end, stored in internal structures of Nebula database. Connecting with DNS names can be used, so client connections can be with DNS names specified.

What this statement means, from documentation for INSERT EDGE ?

When inserting an edge that already exists, INSERT VERTEX *overrides* the edge.

I’ve executed some queries using FETCH with VertexID but for first request for specific VertexID always got

[ERROR (-1005)]: Storage Error: Not the leader of 103. Please retry later.

second request returns valid response. Also some request don’t return any results for keys that were inserted earlier. I’ve upgraded my cluster to 3.3.0 version from 3.2.1 one node at a time. fyi: one parameter for rocksdb I’ve changed

--rocksdb_compression_per_level=no:no:lz4:lz4:lz4hc:lz4hc:lz4hc

from default setting that was empty string can that change have impact to not be able to query some of the data ? I’ve actually changed another one, using query optimizer, previously it was disabled !

--enable_optimizer=true

Did you tested compression change on already populated database and is there need to execute some compaction or some other action to have data available for query ?

Here are some errors I’ve got when executing LOOKUP query

E20221129 23:24:55.530879 332829 StorageAccessExecutor.h:39] IndexScanExecutor failed, error E_RPC_FAILURE, part 90
E20221129 23:24:55.530885 332829 StorageAccessExecutor.h:39] IndexScanExecutor failed, error E_RPC_FAILURE, part 92
E20221129 23:24:55.530894 332829 StorageAccessExecutor.h:39] IndexScanExecutor failed, error E_RPC_FAILURE, part 95
E20221129 23:24:55.530901 332829 StorageAccessExecutor.h:39] IndexScanExecutor failed, error E_RPC_FAILURE, part 96
E20221129 23:24:55.530913 332829 StorageAccessExecutor.h:136] Storage Error: part: 124, error: E_RPC_FAILURE(-3).
E20221129 23:24:55.530952 332825 QueryInstance.cpp:137] Storage Error: part: 124, error: E_RPC_FAILURE(-3).

Hi Team. Got a query. I've defined an edge type with four properties in it. I'm using rank to add multiple edges with same edge type, source vertex, destination vertex by using different rank values(These edges differ in properties). My flow to add an edge (Implementation in Java using nebula-jdbc) is the following 1. I query to check if an edge with the same properties exists. 2. If it doesn't exists, I query again to get the max rank of the edge type between the vertices 3. Now, after fetching the max rank, I increment it and then create a new edge with the incremented rank. My questions: 1. Suppose I do a parallel write and when I try to get the max rank, there is a possibility for the same max rank to be returned when things run in parallel. In such a case, two parallel write requests with the max rank will be executed. This doesn't create two different edges but overrides one another. How should it be handled? 2. If there is a better approach to handle this, kindly let me know.

Hi team. Is there an option to send logs to syslog? If yes, can you please share the procedure

Hi. I've enabled the "redirect_stdout" flag in the conf file. Although, I've enabled it, corresponding logs are not being written to the stdout.log file, while logs are being written to the stderr.log file correctly. Anyone facing similar issue?

Hello, I've been trying to implement versioning/data provenance by using edge attributes - data could be versioned/have provenance tracked by having edges of the same type between two entities only differing by a version/dataset attribute. It seems though that you cannot have edges like that. Is that expected? This caught me somewhat by surprise and I checked with Neo4j and they allow that. Am I doing something wrong or is it a design decision?

It is by design, last property overwrite previous, but you can use RANK to differentiate same edge type versions. That feature can’t be used with Cypher queries.

OpenCypher has no such concept as rank.

Hi team! I've a tag type "report" and have stored the id of a report as a edge property. When I try to retrieve the report id(stored as edge property) using GO query and then use FETCH query to get the report details, the following error is thrown "[ERROR (-1009)]: SemanticError: `reportIDs', the srcs should be type of FIXED_STRING, but was`__EMPTY__'". Can't we store the id as edge property and then retrieve it and use it in FETCH query? Please find the query below: GO FROM "196.210.231.155" OVER edge_type_1 REVERSELY YIELD id($$) as idList | GO FROM $-.idList OVER edge_type_2 YIELD properties(edge).report_id as reportIDs | FETCH PROP ON report $-.reportIDs YIELD vertex as v;

Just observation here, it looks like some of the properties on edge are empty, but in general it looks strange. Maybe you can add filter to get only edges with properties which are not empty.

Hi team. Is there support to run NebulaGraph in Debian OS v11?

should be fine, not precisely tested though, you could try with the closest .deb package for Ubuntu, just in case anything unexpected happens, let the community know:)

Hi Team. In the "Show Hosts" table, is there an option to update the IP with domain?

Hi Team. Does nebula graph support sharing subgraphs with graph database style to other users? If I want to share permissions for a subgraph in a large graph database to others, how should I do that?

Hi, I am just starting utilising nebula and I was wondering if it would be better to use a single connection for all my queries or to open multiple, one for each transaction?

Hi, does Nebula Exchange support importing data from Neo4j version 5 and onwards? On the documentation it states that it is using driver version 4.0.1

hi, I'm wondering about the different usage of

EMPTY

and

NULL

, when displaying an edge with one missing vertex. it seems that if a source vertex is missing, Nebula displays EMPTY (and you can filter with: IS NOT EMPTY). However, if a destination vertex is missing, Nebula displays NULL (and you can filter with: IS NOT NULL). Is there a reason for such difference, and is it safe to rely on such EMPTY/NULL filtering in queries (or is this likely to change in new Nebula versions)? Here is a short example:

CREATE TAG player(name string)
CREATE EDGE follow()
INSERT VERTEX player(name) VALUES "001":("John")
INSERT VERTEX player(name) VALUES "002":("Michael")
INSERT EDGE follow () VALUES '001' -> '002':()

(manager@nebula) [rlgraph]> GO FROM '001' OVER follow YIELD $^.player.name as player1, $$.player.name AS player2
| player1 | player2   |
| "John"  | "Michael" |

DELETE VERTEX '001'

(manager@nebula) [rlgraph]> GO FROM '001' OVER follow YIELD $^.player.name as player1, $$.player.name AS player2
| player1 | player2   |
|         | "Michael" |

INSERT VERTEX player(name) VALUES "001":("John")
DELETE VERTEX '002'

(manager@nebula) [rlgraph]> GO FROM '001' OVER follow YIELD $^.player.name as player1, $$.player.name AS player2
| player1 | player2  |
| "John"  | __NULL__ |