How to merge old data to save space in Elasticsearch - elasticsearch

I tried to find information about this, but I have not find what I was looking for.
I am storing metrics every minutes in an Elasticsearch database. My idea is that the frequency is important only in a short period.
For example, I want to have my metrics every minutes for the last past week, but then I would like to merge these metrics in order to have only one document of metrics for each past weeks.
Thus, I have an idea to achieve this with a stream processing framework such as Spark streaming or Flink, but my question is : is there a native way / tool / tricks to make it happen in Elasticsearch ?
Thank you, hope my question is clear enough, otherwise leave a comment for more details.

One idea would be to have a weekly index in which you store all your metrics every minutes, once the week has passed, you could run an aggregation query on the past week index and aggregate all info at the day or week level. You'd then store that weekly aggregated information as new document in another historical index that you can query later on. I don't think it's necessary to leverage Spark streaming for this, ES aggregations can do the job pretty easily.

Related

Implements popular keyword in ElasticSearch

I'm using ElasticSearch on AWS EC2.
And i want to implement today's popular keyword function in ES.
there is 3 indexes(place, genre, name), and i want see today's popular keyword in name index only.
I tried to use ES slowlog and logstash. but slowlog save logs every shard's log.
(ex)number of shards : 5 then 5 query log saved.
Is there any good and easy way to implement popular keyword in ES?
As far as I know, this is not supported by Elasticsearch and you need to build your own custom solution.
Design you mentioned using the slowlog is not good as you mentioned its on per shard basis, even if you do some more computing and able to merge and relate them to a single search at index level, it would not be good, as
you have to change the slow log configuration and for every index there needs to be a different threshold, you can change it to 0ms, to make sure you get all the search queries in slow logs, but that would take a huge disk space and would not be good for Elasticsearch performance.
You have to do some parsing of slow log in your application and if you do it runtime it would be very costly.
I think you can maintain a distributed cache in your application where you store the top searched keyword like the leaderboard of a multi-player gaming app, which is changing very frequently but in your case, you don't even have to update this cache very frequently. I would not go into much implementation details, but simple Hashmap of search term as key and count as value would solve the issue.
Hope this helps. let me know if you have questions.

Re-processing data for Elasticsearch with a new pipeline

I have an ELK-stack server that is being used to analyse Apache web log data. We're loading ALL of the logs, going back several years. The purpose is to look at some application-specific trends over this time period.
The data-processing pipeline is still being tweaked, as this is the first time anyone has looked in detail into this data and some people are still trying to decide how they want the data to be processed.
Some changes were suggested and while they're easy enough to do in the logstash pipeline for new, incoming data, I'm not sure how to apply these changes to the data that's already in elastic. It took several days to load the current data set, and quite a bit more data has been added so re-processing everything through logstash, with the modified pipeline will probably take several days longer.
What's the best way to apply these changes to data that has already been ingested into elastic? In the early stages of testing this set-up, I would just remove the index and rebuild from scratch, but that was done with very limited data sets and with the amount of data in use here, I'm not sure that's feasible. Is there a better way?
Setup an ingest pipeline and use reindex API to move data from current index to new index (with the pipeline configured for destination index)
Ingest Node

Reasons & Consequences of putting a Date in Elastic Index Name

I am looking at sending my App logs to Elastic (6.x) via FileBeat and Logstash. As mentioned in Configure the Logstash output and recommended elsewhere, it seems that I need add the Date to the Index name. The reason for doing so was that when the time came to delete old data, it was easier to delete an entire Index by date, rather than individual documents. Is this true?
If I should be following this recommendation of adding the Date to the Index Name, I’m curious what additional things I need to do to ensure seamless querying? By this I mean querying esp. in Kibana, for e.g. over the past day which would need to look at today’s index as well as yesterday’s index.
Speaking of querying in Kibana, is there a way of simply working with the base index name without the date stamp i.e. setting it up so that I do not see or have to deal with the date named indexes?
Edit: Kamal raised a good point that I have not provided any information about my cluster and my needs. The following is what I'm working with:
What is your daily data creation/expected count
I'm not sure. I don't expect anything more than a GB of data day, and no more than a couple of 100K documents a day. Since these are logs, I don't expect any updates to the documents once they are created.
Growth rate of the data in the future (1 year - 5 years)
At the moment, I don't see the growth rate to cross a GB a day.
How many teams are using the same cluster apart from yours if there is
any
The cluster would be used (actually queried) by just my team. We are about 5 right now, but I don't see more than 10 users (and that's not concurrent, just over a day or month)
Usage patterns, type of queries used etc.
I'm not sure, but there certainly would not be updates to the data other than deletions
Hardware details
I've not worked this out with management. For most part I expect 3 nodes. Also this is not critical i.e. if we lose all of our logs for some reason, I would not lose sleep over it.
First of all you need to take a step back and understand do you really need multiple index or single one(where you need to filter documents while querying using a date field for a particular date).
Some of questions you must have before you take on such decision
What is your daily data creation/expected count
Growth rate of the data in the future (1 year - 5 years)
How many teams are using the same cluster apart from yours if there is any
Usage patterns, type of queries used etc.
Hardware details
Advantages
In a way, having multiple indexes(with date field as its index name) would be more beneficial.
You can delete the old indexes without affecting new ones.
In case if you have to change the mapping, you can do so with the new index without affecting the old ones. Comparatively less overhead while for single index, you have to reindex all the documents which would take lot more time if size is pretty huge. And if this keeps happening every now and then, you would need to come up with solution where you have to execute such operations at the times of minimal usages. That means, it can harm productivity.
searching using multiple indexes still is convenient.
not really sure but its easier for scaling using multiple indexes.
Disadvantages are:
Additional shards are created for each and every index that can waste some storage space.
Overhead to maintain multiple indexes by monitoring/operations team.
At times can lead to over-creation of indexes.
No mapping changes and less documents insertion(in 100s or few 100s), it'd be better to use single index.
The only way and the only correct way to figure out what's best is to have a cluster that closely resembles the production one with data too resembling to production, try various configurations and see which solution fits best.
Speaking of querying in Kibana, is there a way of simply working with
the base index name without the date stamp i.e. setting it up so that
I do not see or have to deal with the date named indexes?
Yes there is. If you have indexes with names like logs-0001, logs-0002, you can use logs-* as indexname when you query.
Including date in an index name is a very common use case implemened by many Elasticsearch users. It helps with archiving/ purging old indices as you mentioned. You dont need to do anything additionally to be able to query. Setup your index basename as an index pattern for your indices for ex. logstash-* and you can query on that particular index pattern in Kibana.

Elasticseach & Kibana - best practice for visualizing one year's logs

I am using ElasticSearch with Kibana to store and visualize data from my logs. I know it is customary to use Logstash, but I just use the elasticsearch Rest API and POST new elements to it.
I am trying to look for best practices in terms of how I should manage my indices, given I have about 50k logs per day, and I want to visualize sometimes weekly, sometimes monthly and sometimes yearly data. And also I have no need for more than one node. I don't need a high available cluster.
So I am basically trying to determine:
-How should I store my indexes, by time? Monthly? Weekly? One index for everything?
-What are the disadvantages of a huge index (one index that contains all my data)? Does it mean that the entire index is in memory?
Thank you.
I like to match indexes to the data retention policy. Daily indexes work very well for log files, so you can expire one day's worth after X days of retention.
The fewer indexes/shards you have, the less RAM is used in overhead by Elasticsearch to manage them.
The mapping for a field is frozen when the field is added to the index. With a daily index, I can update the mapping and have it take effect for the new indexes, and wait for the old ones to expire. With a longer-term indexes, you'd probably need to reindex the data, which I always try to avoid.
The settings for shards and replicas are also frozen when you create the index.
You can visualize them in Kibana regardless of how they're stored. Use the #timestamp field as your X-axis and change the "interval" to the period you want.
Using logstash would be important if you wanted to alter your logs at all. We do a lot of normalization and creation of new fields, so it's very helpful. If it's not a requirement for you, you might also look into filebeats, which can write directly to elasticsearch.
Lots to consider...

ElasticSearch - Operational Insights , and Trends

Given an ElasticSearch Installation, I want to know current trends and insights. I am not sure if Aggregators would help here.
What are the top queries for last 24 hours?
Most frequently searched terms in last 24 hours? etc.
Most accessed documents in last 24 hours?
Is there any way to collect and get hold of these metrics from ElasticSearch.
A typical use case- As a user visits the homepage, i want to show the trending searches, and top content.
One alternative if you do not want to load your existing ElasticSearch installation with additional metrics is to send this data to a log management solution on the cloud -- such as Loggly, Logentries, etc.

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