I'm using nebula docker but it throws me an error when I connected first. Then I retried everything is ok. Why is that? Must I retry every time?
This is likely caused by setting the heartbeat_interval_secs value to fetch data from the meta server. Conduct the following steps to resolve:
If meta has registered, check heartbeat_interval_secs value in console with the following command.
nebula> GET CONFIGS storage:heartbeat_interval_secs
nebula> GET CONFIGS graph:heartbeat_interval_secs
If the value is large, change it to 1s with the following command.
nebula> UPDATE CONFIGS storage:heartbeat_interval_secs=1
nebula> UPDATE CONFIGS graph:heartbeat_interval_secs=1
Note the changes take effect in the next period.
I was doing some R&D on table field alterations. So, I needed a clone of an table.
I ran the command "create table <table name> as select * from <old table>" and it worked.
However, when I ran the second time, I cancelled the command in between and after that I am getting the below error.
$ select count(*) from my_table_copy;
SQL -211: Cannot read system catalog (systables).
ISAM -154: ISAM error: Lock Timeout Expired
SQLSTATE: IX000 at /dev/stdin:1
When I tried to fetch the DB through Open Admin, there also am getting the error:
256 : Database query failed: -
Error: -244 [Informix][Informix ODBC Driver][Informix]Could not do a
physical-order read to fetch next row. sqlerrm(systables)
(SQLExecute[-244] at
How to resolve this?
Thanks,
You must be getting these lock errors, because engine is rolling back your clone table transaction.
Check with "onstat -x" if there is a transaction with an R on the flags column. The est. rb_time column shows an estimate of recovery complete process.
My suggestion? If you don't need exactly the same actual data on the new table, you can put a "SET ISOLATION TO DIRTY READ;" right before your create table command.
I just created a new folder name-Test and started Neo4j server.
When i run the below script, i get the error - "Neo.ClientError.Statement.EntityNotFound"
and a message "Node with id 0"
start root=node(0)
create
(tatham {Name:'Tatham'}),
(tom {Name:'Tom'}),
(pat {Name:'Pat'}),
(chrissy {Name:'Chrissy'}),
(sailing {Name:'Sailing'}),
(mtb {Name:'MTB'}),
(rowing {Name:'Rowing'}),
(tennis {Name:'Tennis'}),
root-[:HAS_USER]->tatham,
root-[:HAS_USER]->tom,
root-[:HAS_USER]->pat,
root-[:HAS_USER]->chrissy,
tatham-[:FRIEND]->tom,
tom-[:FRIEND]->pat,
tatham-[:FRIEND]->chrissy,
tatham-[:LIKES]->sailing,
tatham-[:LIKES]->mtb,
tom-[:LIKES]->sailing,
pat-[:LIKES]->mtb,
tom-[:LIKES]->rowing,
pat-[:LIKES]->tennis,
chrissy-[:LIKES]->mtb,
chrissy-[:LIKES]->sailing
Can you kindly help me hot to fix this issue
A #WilliamLyon indicated:
A new DB has no nodes, and therefore has no node with the ID of 0.
The START clause is now deprecated.
You are apparently using a very old version of neo4j. If possible, you should install the latest version.
In addition:
Nodes now must always be specified within parentheses.
Try the following, instead, which should work with your version of neo4j as well as the latest versions:
CREATE
(tatham {Name:'Tatham'}),
(tom {Name:'Tom'}),
(pat {Name:'Pat'}),
(chrissy {Name:'Chrissy'}),
(sailing {Name:'Sailing'}),
(mtb {Name:'MTB'}),
(rowing {Name:'Rowing'}),
(tennis {Name:'Tennis'}),
(root)-[:HAS_USER]->(tatham),
(root)-[:HAS_USER]->(tom),
(root)-[:HAS_USER]->(pat),
(root)-[:HAS_USER]->(chrissy),
(tatham)-[:FRIEND]->(tom),
(tom)-[:FRIEND]->(pat),
(tatham)-[:FRIEND]->(chrissy),
(tatham)-[:LIKES]->(sailing),
(tatham)-[:LIKES]->(mtb),
(tom)-[:LIKES]->(sailing),
(pat)-[:LIKES]->(mtb),
(tom)-[:LIKES]->(rowing),
(pat)-[:LIKES]->(tennis),
(chrissy)-[:LIKES]->(mtb),
(chrissy)-[:LIKES]->(sailing);
The root node will be created automatically the first time it is encountered by the query, and then re-used.
The problem is the first line of your Cypher query: start root=node(0). That statement is saying "find a Node with id 0", however if you haven't inserted any data yet there is no Node to find, thus the error.
start has been deprecated and is no longer required so you can just remove it.
In our unit testing suite, we create and destroy a large number of SQLite databases that use the path of ":memory:". Occasionally, and only when running on the iOS simulator, the creation of those databases fails with the rather enigmatic message:
Database ":memory:": unable to open database file
99% of the time, these requests succeed. (Subsequent tests within the same test run typically succeed after this failure occurs.) But when you're using this in an automated build-acceptance test, you want 100%.
We've instrumented for memory consumption (it's within normal limits) and disk-space availability (20GB+ available).
Any ideas?
UPDATE: Captured this happening with extra logging per Richard's suggestion below. Here's the log output:
SQLITE ERROR: (28) attempt to open "/Users/xxx/Library/Developer/CoreSimulator/Devices/CF762060-7D23-4C79-A466-7F20AB6233E7/data/Containers/Data/Application/582E1ED0-81E0-4CC7-A6F6-DBEBC101BBE8/tmp/etilqs_1ghbf1MSTa8ilSj" as
SQLITE ERROR: (14) cannot open file at line 30595 of [f66f7a17b7]
SQLITE ERROR: (14) os_unix.c:30595: (17) open(/Users/xxx/Library/Developer/CoreSimulator/Devices/CF762060-7D23-4C79-A466-7F20AB6233E7/data/Containers/Data/Application/582E1ED0-81E0-4CC7-A6F6-DBEBC101BBE8/tmp/etilqs_1ghbf1MST
I've noticed that even a :memory: database will files on disk if you create a temporary table. The temporary files for unix system are built by a Prng, so there is a non-zero chance of name collision if lots and lots of temporary files are created simultaneously. Or, if the disk is full, the create could fail. Or if for some reason the unix temp directory is not accessible either because it's been deleted or permissions on it are invalid.
For example, I've turned on several loggers in sqlite3 command line by adding these command line arguments to llvc-gcc: -DSQLITE_DEBUG_OS_TRACE=1 -DSQLITE_TEST=1 -DSQLITE_DEBUG=1 then I observed a temp file being created from the command line using this SQL:
$ ./sqlite3
SQLite version 3.8.8.2 2015-01-30 14:30:45
Enter ".help" for usage hints.
Connected to a transient in-memory database.
Use ".open FILENAME" to reopen on a persistent database.
sqlite> create temporary table t( x );
OPENX 3 /var/folders/nf/l1cw8sn1707b73zy5nqycrpw0000gn/T//etilqs_fvwR6KbMm518S4w 01002
OPEN 3
WRITE 3 512 0 0
OPENX 4 /var/folders/nf/l1cw8sn1707b73zy5nqycrpw0000gn/T//etilqs_OJJJ1lrTtQIFnUO 05402
OPEN 4
WRITE 4 1024 0 0
WRITE 4 1024 1024 0
WRITE 3 28 0 0
sqlite>
No ideas. But perhaps if you turned on the error and warning log it will give some clues.
I'm trying to use the Java API for Neo4j but I seem to be stuck at IndexHits. If I query the DB with Cypher using
START n=node:types(type="Process") RETURN n;
I get all 2087 nodes of type "Process".
In my application I have the following lines
Index<Node> nodeIndex = db.index().forNodes("types");
IndexHits<Node> hits = nodeIndex.get("type", "Process");
System.out.println("Node index size: " + hits.size());
which leads my console to spit out a value of 0. Here, db is of course an instance of GraphDatabaseService.
I expected an object that included all 2087 nodes. What am I doing wrong?
The .size() question is just the prelude to my iterator
for(Node process : hits) { ... }
but that does not much when hits.size() == 0. According to http://api.neo4j.org/1.9.2/org/neo4j/graphdb/index/IndexHits.html this should be possible, provided there is something in hits.
Thanks in advance for your help.
I figured it out. Man, I feel so embarrassed...
It so happens that I had set up the DB_PATH to my default data folder, whereas the default storage folder is the default data folder plus graph.db. When I tried to run the code from that corrected DB_PATH I got an error saying that a lock file was in place because the Neo4j server was running. After shutting it down it worked perfectly.
So, if you happen to see the following error, just stop the server and run the code again:
Caused by: org.neo4j.kernel.StoreLockException: Could not create lock file
at org.neo4j.kernel.StoreLocker.checkLock(StoreLocker.java:74)
at org.neo4j.kernel.StoreLockerLifecycleAdapter.start(StoreLockerLifecycleAdapter.java:40)
at org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:491)
I found on several forums that you cannot run the Neo4j server and use the Java API to query it at the same time.