The Cube software (https://github.com/square/cube) allows you to retrieve events.
I want to retrieve a lot of events. But it appears that I am capped at 1000. There are well over 9000 in mongodb in the collection and time range I am querying
Example http GET queries I issue:
# 1000 results
http://1.2.3.4:1081/1.0/event?expression=my_event_type
# 1000 results
http://1.2.3.4:1081/1.0/event?expression=my_event_type&start=2012-02-02&stop=2013-07-03
# 7 results
http://1.2.3.4:1081/1.0/event?expression=my_event_type&limit=7
# 1000 results
http://1.2.3.4:1081/1.0/event?expression=my_event_type&limit=9999
It appears that the limit is pinned:
https://github.com/square/cube/blob/28dad4af27a6680deb46077b16952590f2c21cad/lib/cube/event.js
Line 166
based on the 'batchSize=1000'
Is it possible that you can 'page' through the data in some way? Or is this just a hard limit?
Looks like there is a hard cap on results in three places that need to be updated for large domains:
event.js - line 166
metric.js - line 11
metric.js - line 12
In addition, I was unable to find any query-string apis for the parameters. Ideally, we can leave the cap at 1000 (to avoid server bloat for people not tuning their queries correctly) and allow the consumer to define override behavior.
Related
I have a large database (100M rows) indexed by SphinxSearch. Each search takes 0.1-0.5s. However, if I run 10 searches concurrently, they take 20s on average.
Is it the expected behaviour of SphinxSearch?
Should I adjust the config or move to another search engine for concurrency?
My config file is simple:
searchd
{
listen = 9312
listen = 9306:mysql41
pid_file = /var/searchd.pid
read_timeout = 30
log = /var/log/sphinxsearch/searchd.log
query_log = /var/log/sphinxsearch/query.log
}
Is it the expected behaviour of SphinxSearch?
It heavily depends on the number of CPUs. If you have more than 10 physical CPUs then latency degradation from 0.5 sec to 20 sec by increasing the concurrency from 1 to 10 is definitely not expected. In this case first of all make sure all your CPUs are busy under the concurrency load. If it's not - depending on your Sphinx version and multi-tasking mode let it run with more threads.
Should I adjust the config or move to another search engine for concurrency?
I recommend Manticore Search as:
it's open source - https://github.com/manticoresoftware/manticoresearch/
it's the only fork of Sphinx and if you are familiar with Sphinx in general it shouldn't be a problem to migrate
hundreds of bugs have been fixed
the multi-tasking mode is completely different (coroutines)
I have run a analysis on Sonarqube with Codescan. The number of issues returned, is way above the 10000 web api limit. Therefore, within my client/code I wanted to loop through all of the rules within a quality profile and return all the issues per rule.
How can I get a list of rules using the web api from java?
You can use api/qualityprofiles/backup. It takes a quality profile key as parameter and returns an xml containing all "active rules".
Newer SonarQube versions do not have the 10K issues limitation.
You have to loop n-times to collect all results.
For example:
Consider a project with 44K issues.
You have to discover first how many issues you have to read, call one time the /api/issues/search with only you project key and the parameter ps ( pagesize ) equal to 100
http:///api/issues/search?componentKeys=&ps=100
You could receive an answer like this
{"total":44130,"p":1,"ps":100,"paging":{"pageIndex":1,"pageSize":100,"total":44130},"issues":[{"key":"AVtoCSNP6OwvnmtEJjae","ru..........
So we have to claim 44130 issues, using a pagesize of 100 then you must call (44130 / 100 ) + 1 times the /api/issues/search for your project and for every request remember to increase by 1 the p ( page ) parameter ( so you can point the right portion of results )
Your sequence of command will be like this
http:///api/issues/search?componentKeys=YOUR_PROJECT_KEY>&ps=100&p=1
http:///api/issues/search?componentKeys=YOUR_PROJECT_KEY>&ps=100&p=2
http:///api/issues/search?componentKeys=YOUR_PROJECT_KEY>&ps=100&p=3
....
http:///api/issues/search?componentKeys=YOUR_PROJECT_KEY>&ps=100&p=442
Parse the result of every call and you will be obtained the list of your issues.
Cheers
Massimo
I am running a very simple performance experiment where I post 2000 documents to my application.
Who in tern persists them to a relational DB and sends them to Solr for indexing (Synchronously, in the same request).
I am testing 3 use cases:
No indexing at all - ~45 sec to post 2000 documents
Indexing included - commit after each add. ~8 minutes (!) to post and index 2000 documents
Indexing included - commitWithin 1ms ~55 seconds (!) to post and index 2000 documents
The 3rd result does not make any sense, I would expect the behavior to be similar to the one in point 2. At first I thought that the documents were not really committed but I could actually see them being added by executing some queries during the experiment (via the solr web UI).
I am worried that I am missing something very big. Is it possible that committing after each add will degrade performance by a factor of 400?!
The code I use for point 2:
SolrInputDocument = // get doc
SolrServer solrConnection = // get connection
solrConnection.add(doc);
solrConnection.commit();
Where as the code for point 3:
SolrInputDocument = // get doc
SolrServer solrConnection = // get connection
solrConnection.add(doc, 1); // According to API documentation I understand there is no need to call an explicit commit after this
According to this wiki:
https://wiki.apache.org/solr/NearRealtimeSearch
the commitWithin is a soft-commit by default. Soft-commits are very efficient in terms of making the added documents immediately searchable. But! They are not on the disk yet. That means the documents are being committed into RAM. In this setup you would use updateLog to be solr instance crash tolerant.
What you do in point 2 is hard-commit, i.e. flush the added documents to disk. Doing this after each document add is very expensive. So instead, post a bunch of documents and issue a hard commit or even have you autoCommit set to some reasonable value, like 10 min or 1 hour (depends on your user expectations).
is there a way to find queries in mongodb that are not using Indexes or are SLOW? In MySQL that is possible with the following settings inside configuration file:
log-queries-not-using-indexes = 1
log_slow_queries = /tmp/slowmysql.log
The equivalent approach in MongoDB would be to use the query profiler to track and diagnose slow queries.
With profiling enabled for a database, slow operations are written to the system.profile capped collection (which by default is 1Mb in size). You can adjust the threshold for slow operations (by default 100ms) using the slowms parameter.
First, you must set up your profiling, specifying what the log level that you want. The 3 options are:
0 - logger off
1 - log slow queries
2 - log all queries
You do this by running your mongod deamon with the --profile options:
mongod --profile 2 --slowms 20
With this, the logs will be written to the system.profile collection, on which you can perform queries as follows:
find all logs in some collection, ordering by ascending timestamp:
db.system.profile.find( { ns:/<db>.<collection>/ } ).sort( { ts: 1 } );
looking for logs of queries with more than 5 milliseconds:
db.system.profile.find( {millis : { $gt : 5 } } ).sort( { ts: 1} );
You can use the following two mongod options. The first option fails queries not using index (V 2.4 only), the second records queries slower than some ms threshold (default is 100ms)
--notablescan
Forbids operations that require a table scan.
--slowms <value>
Defines the value of “slow,” for the --profile option. The database logs all slow queries to the log, even when the profiler is not turned on. When the database profiler is on, mongod the profiler writes to the system.profile collection. See the profile command for more information on the database profiler.
You can use the command line tool mongotail to read the log from the profiler within a console and with a more readable format.
First activate the profiler and set the threshold in milliseconds for the profile to consider an operation to be slow. In the following example the threshold is set to 10 milliseconds for a database named "sales":
$ mongotail sales -l 1
Profiling level set to level 1
$ mongotail sales -s 10
Threshold profiling set to 10 milliseconds
Then, to see in "real time" the slow queries, with some extra information like the time each query took, or how many registries it need to "walk" to find a particular result:
$ mongotail sales -f -m millis nscanned docsExamined
2016-08-11 15:09:10.930 QUERY [ops] : {"deleted": {"$exists": false}, "prod_id": "367133"}. 8 returned. nscanned: 344502. millis: 12
2016-08-11 15:09:10.981 QUERY [ops] : {"deleted": {"$exists": false}, "prod_id": "367440"}. 6 returned. nscanned: 345444. millis: 12
....
In case somebody ends up here from Google on this old question, I found that explain really helped me fix specific queries that I could see were causing COLLSCANs from the logs.
Example:
db.collection.find().explain()
This will let you know if the query is using a COLLSCAN (Basic Cursor) or an index (BTree), among other things.
https://docs.mongodb.com/manual/reference/method/cursor.explain/
While you can obviously use Profiler a very neat feature of Mongo DB due to which I actually fall in love with it is Mongo DB MMS.
Takes less than 60 seconds and can manage from anywhere. I am sure you will Love it.
https://mms.mongodb.com/
UPDATE I have put up a follow up question that contains updated scripts and and a clearer setup on neo4j performance compared to mysql (how can it be improved?). Please continue there./UPDATE
I have some problems verifying the performance claims made in the "graph databases" book (page 20) and in the neo4j (chapter 1).
To verify these claims I created a sample dataset of 100000 'person' entries with 50 'friends' each, and tried to query for e.g. friends 4 hops away. I used the very same dataset in mysql. With friends of friends over 4 hops mysql returns in 0.93 secs, while neo4j needs 65 -75 secs (on repeated calls).
How can I improve this miserable outcome, and verify the claims made in the books?
A bit more detail:
I run the whole setup on a i5-3570K with 16GB Ram, using ubuntu12.04 64bit, java version "1.7.0_25" and mysql 5.5.31, neo4j-community-2.0.0-M03 (I get a similar outcome with 1.9)
All code/sample data can be found on https://github.com/jhb/neo4j-experiements/ (to be used with 2.0.0). The resulting sample data in different formats can be found on https://github.com/jhb/neo4j-testdata.
To use the scripts you need a python with mysql-python, requests and simplejson installed.
the dataset is created with friendsdata.py and stored to friends.pickle
friends.pickle gets imported to neo4j using import_friends_neo4j.py
friends.pickle gets imported to mysql using import_friends_mysql.py
I add indexes on t_user_friend.* in mysql
I added "create index on :node(noscenda_name) in neo4j
To make life a bit easier the friends.*.bz2 contain sql and cypher statements to create those datasets in mysql and neo4j 2.0 M3.
Mysql performance
I first warm mysql up by querying:
select count(distinct name) from t_user;
select count(distinct name) from t_user;
Then, for the real meassurment I do
python query_friends_mysql.py 4 10
This creates the following sql statement (with changing t_user.names):
select
count(*)
from
t_user,
t_user_friend as uf1,
t_user_friend as uf2,
t_user_friend as uf3,
t_user_friend as uf4
where
t_user.name='person8601' and
t_user.id = uf1.user_1 and
uf1.user_2 = uf2.user_1 and
uf2.user_2 = uf3.user_1 and
uf3.user_2 = uf4.user_1;
and repeats this 4 hop query 10 times. The queries need around 0.95 secs each. Mysql is configured to use a key_buffer of 4G.
neo4j performance testing
I have modified neo4j.properties:
neostore.nodestore.db.mapped_memory=25M
neostore.relationshipstore.db.mapped_memory=250M
and the neo4j-wrapper.conf:
wrapper.java.initmemory=2048
wrapper.java.maxmemory=8192
To warm up neo4j I do
start n=node(*) return count(n.noscenda_name);
start r=relationship(*) return count(r);
Then I start using the transactional http endpoint (but I get the same results using the neo4j-shell).
Still warming up, I run
./bin/python query_friends_neo4j.py 3 10
This creates a query of the form (with varying person ids):
{"statement": "match n:node-[r*3..3]->m:node where n.noscenda_name={target} return count(r);", "parameters": {"target": "person3089"}
after the 7th call or so each call needs around 0.7-0.8 secs.
Now for the real thing (4 hops) I do
./bin/python query_friends_neo4j.py 4 10
creating
{"statement": "match n:node-[r*4..4]->m:node where n.noscenda_name={target} return count(r);", "parameters": {"target": "person3089"}
and each call takes between 65 and 75 secs.
Open questions/thoughts
I'd really like see the claims in the books to be reproducable and correct, and neo4j faster then mysql instead of magnitudes slower.
But I don't know what I am doing wrong... :-(
So, my big hopes are:
I didn't do the memory settings for neo4j correctly
The query I use for neo4j is completely wrong
Any suggestions to get neo4j up to speed are highly welcome.
Thanks a lot,
Joerg
2.0 has not been performance optimized at all, so you should use 1.9.2 for comparison.
(if you use 2.0 - did you create an index for n.noscenda_name)
You can check the query plan with profile start ....
With 1.9 please use a manual index or node_auto_index for noscenda_name.
Can you try these queries:
start n=node:node_auto_index(noscenda_name={target})
match n-->()-->()-->m
return count(*);
Fulltext indexes are also more expensive than exact indexes, so keep the exact auto-index for noscenda_name.
can't get your importer to run, it fails at some point, perhaps you can share the finished neo4j database
python importer.py
reading rels
reading nodes
delete old
Traceback (most recent call last):
File "importer.py", line 9, in <module>
g.query('match n-[r]->m delete r;')
File "/Users/mh/java/neo/neo4j-experiements/neo4jconnector.py", line 99, in query
return self.call(payload)
File "/Users/mh/java/neo/neo4j-experiements/neo4jconnector.py", line 71, in call
self.transactionurl = result.headers['location']
File "/Library/Python/2.7/site-packages/requests-1.2.3-py2.7.egg/requests/structures.py", line 77, in __getitem__
return self._store[key.lower()][1]
KeyError: 'location'
Just to add to what Michael said, in the book I believe the authors are referring to a comparison that was done in the Neo4j in Action book - it's described in the free first chapter of that book.
At the top of page 7 they explain that they were using the Traversal API rather than Cypher.
I think you'll struggle to get Cypher near that level of performance at the moment so if you want to do those types of queries you'll want to use the Traversal API directly and then perhaps wrap it in an unmanaged extension.