I need to destructurate my index mapping.
My index has the following mapping
"A": {
"properties": {
"B": {
"properties": {
-c
-d
-e
}
}
}
}
What I need is to delete "one level" in order to have a mapping like this:
"A": {
"properties": {
-c
-d
-e
}
}
Is it possible to obtain this result without reindexing all my data?
Short answer, No.
Longer answer, also No. This question has been asked so many times. The answer will always be no and this is why :
You can only find that which is stored in your index. In order to make your data searchable, your database needs to know what type of data each field contains and how it should be indexed. If you switch a field type from e.g. a string to a date, all of the data for that field that you already have indexed becomes useless. One way or another, you need to reindex that field.
This applies not just to Elasticsearch, but to any database that uses indices for searching. And if it isn't using indices then it is sacrificing speed for flexibility.
Elasticsearch (and Lucene) stores its indices in immutable segments — each segment is a “mini" inverted index. These segments are never updated in place. Updating a document actually creates a new document and marks the old document as deleted. As you add more documents (or update existing documents), new segments are created. A merge process runs in the background merging several smaller segments into a new big segment, after which the old segments are removed entirely.
Typically, an index in Elasticsearch will contain documents of different types. Each _type has its own schema or mapping. A single segment may contain documents of any type. So, if you want to change the field definition for a single field in a single type, you have little option but to reindex all of the documents in your index.
If you are interested with more info, you can read the rest of the excerpt here by Clinton Gormley.
I also suggest the following readings :
Elasticsearch Zero Downtime Reindexing – Problems and Solutions
The SO question : Is there a smarter way to reindex elasticsearch?
You have to create a new index with the updated (one level deleted) mapping. You cannot updated the same mapping to achieve what you want.
Related
I have an elasticsearch index, my_index, with millions of documents, with key my_uuid. On top of that index I have several filtered aliases of the following form (showing only my_alias as retrieved by GET my_index/_alias/my_alias):
{
"my_index": {
"aliases": {
"my_alias": {
"filter": {
"terms": {
"my_uuid": [
"0944581b-9bf2-49e1-9bd0-4313d2398cf6",
"b6327e90-86f6-42eb-8fde-772397b8e926",
thousands of rows...
]
}
}
}
}
}
}
My understanding is that the filter will be cached transparently for me, without having to do any configuration. The thing is I am experiencing very slow searches, when going through the alias, which suggests that 1. the filter is not cached, or 2. it is wrongly written.
Indicative numbers:
GET my_index/_search -> 50ms
GET my_alias/_search -> 8000ms
I can provide further information on the cluster scale, and size of data if anyone considers this relevant.
I am using elasticsearch 2.4.1. I am getting the right results, it is just the performance that concerns me.
Matching each document with a 4MB list of uids is definetly not the way to go. Try to imagine how many CPU cycles it requires. 8s is quite fast.
I would duplicate the subset of data in another index.
If you need to immediately reflect changes, you will have to manage the subset index by hand :
when you delete a uuid from the list, you delete the corresponding documents
when you add a uuid, you copy the corresponding documents (reindex api with a query is your friend)
when you insert a document, you have to check if the document should be added in subset index too
when you delete a document, delete it in both indices
Force the document id so they are the same in both indices. Beware of refresh time if you store the uuid list in elasticsearch index.
If updating the subset with new uuid is not time critical, you can just run the reindex every day or every hour.
Is there any way to update all data in elasticsearch.
In below example, update done for external '1'.
curl -XPOST 'localhost:9200/customer/external/1/_update?pretty' -d '
{
"doc": { "name": "Jane Doe", "age": 20 }
}'
Similarly, I need to update all my data in external. Is there any way or query to updating all data.
Updating all documents in an index means that all documents will be deleted and new ones will be indexed. Which means lots of "marked-as-deleted" documents.
When you run a query ES will automatically filter out those "marked-as-deleted" documents, which will have an impact on the response time of the query. How much impact it depends on the data, use case and query.
Also, if you update all documents, unless you run a _force_merge there will be segments (especially the larger ones) that will still have "marked-as-deleted" documents and those segments are hard to be automatically merged by Lucene/Elasticsearch.
My suggestion, if your indexing process is not too complex (like getting the data from a relational database and process it before indexing into ES, for example), is to drop the index completely and index fresh data. It might be more effective than updating all the documents.
Theres an index that I want to apply updated mappings to, I have done my best to follow the documentation on ES and Stackoverflow but I am now stuck.
The original index: logstash-index-YYYY.MM with data in it
I created index: logstash-index-new-YYYY.MM (which has a template for the new mapping)
Using the following query:
/logstash-index-YYYY.MM/_search?search_type=scan&scroll=1m
{
"query": {
"match_all": {}
},
"size": 30000
}
I get a _scroll_id and I have less than 30k docs so I should only need to run once.
How do I use that id to push the data into the new index?
You are not using scrollid to push the data into the new index. You use it to get another portion of data from the scroll query.
When you run scan query, first pass doesn't return any results, it scans through shards in your cluster and returns scrollid. Another pass (using scrollid from first one) will return actual results.
If you want to put that data into new index you should write some kind of simple program in language of your choice that will get this data and then put it into your new index.
There is a very good article on elasticsearch blog how to change mappings of your indices on the fly. Unfortunately, reindexing itself is not covered there.
I'm planning a strategy for querying millions of docs in date and user directions.
Option 1 - indexing by user. routing by date.
Option 2 - indexing by date. routing by user.
What are the differences or advantages when using routing or indexing?
One of the design patterns that Shay Banon # Elasticsearch recommends is: index by time range, route by user and use aliasing.
Create an index for each day (or a date range) and route documents on user field, so you could 'retire' older logs and you don't need queries to execute on all shards:
$ curl -XPOST localhost:9200/user_logs_20140418 -d '{
"mappings" : {
"user_log" : {
"_routing": {
"required": true,
"path": "user"
},
"properties" : {
"user" : { "type" : "string" },
"log_time": { "type": "date" }
}
}
}
}'
Create an alias to filter and route on users, so you could query for documents of user_foo:
$ curl -XPOST localhost:9200/_aliases -d '{
"actions": [{
"add": {
"alias": "user_foo",
"filter": {"term": {"user": "foo"}},
"routing": "foo"
}
}]
}'
Create aliases for time windows, so you could query for documents this_week:
$ curl -XPOST localhost:9200/_aliases -d '{
"actions": [{
"add": {
"index": ["user_logs_20140418", "user_logs_20140417", "user_logs_20140416", "user_logs_20140415", "user_logs_20140414"],
"alias": "this_week"
},
"remove": {
"index": ["user_logs_20140413", "user_logs_20140412", "user_logs_20140411", "user_logs_20140410", "user_logs_20140409", "user_logs_20140408", "user_logs_20140407"],
"alias": "this_week"
}
}]
}'
Some of the advantages of this approach:
if you search using aliases for users, you hit only shards where the users' data resides
if a user's data grows, you could consider creating a separate index for that user (all you need is to point that user's alias to the new index)
no performance implications over allocation of shards
you could 'retire' older logs by simply closing (when you close indices, they consume practically no resources) or deleting an entire index (deleting an index is simpler than deleting documents within an index)
Indexing is the process of parsing
[Tokenized, filtered] the document that you indexed[Inverted Index]. It's like appendix of an text book.
When the indexed data exceeds one server limit. instead of upgrading server configurations, add another server and share data with them. This process is called as sharding.
If we search it will search in all shards and perform map reduce and return results.If we group similar data together and search some data in specific data means it reduce processing power and increase speed.
Routing is used to store group of data in particular shards.To select a field for routing. The field should be present in all docs,field should not contains different values.
Note:Routing should be used in multiple shards environment[not in single node]. If we use routing in single node .There is no use of it.
Let's define the terms first.
Indexing, in the context of Elasticsearch, can mean many things:
indexing a document: writing a new document to Elasticsearch
indexing a field: defining a field in the mapping (schema) as indexed. All fields that you search on need to be indexed (and all fields are indexed by default)
Elasticsearch index: this is a unit of configuration (e.g. the schema/mapping) and of data (i.e. some files on disk). It's like a database, in the sense that a document is written to an index. When you search, you can reach out to one or more indices
Lucene index: an Elasticsearch index can be divided into N shards. A shard is a Lucene index. When you index a document, that document gets routed to one of the shards. When you search in the index, the search is broadcasted to a copy of each shard. Each shard replies with what it knows, then results are aggregated and sent back to the client
Judging by the context, "indexing by user" and "indexing by date" refers to having one index per user or one index per date interval (e.g. day).
Routing refers to sending documents to shards as I described earlier. By default, this is done quite randomly: a hash range is divided by the number of shards. When a document comes in, Elasticsearch hashes its _id. The hash falls into the hash range of one of the shards ==> that's where the document goes.
You can use custom routing to control this: instead of hashing the _id, Elasticsearch can hash a routing value (e.g. the user name). As a result, all documents with the same routing value (i.e. same user) land on the same shard. Routing can then be used at query time, so that Elasticsearch queries just one shard (per index) instead of N. This can bring massive query performance gains (check slide 24 in particular).
Back to the question at hand, I would take it as "what are the differences or advantages when breaking data down by index or using routing?"
To answer, the strategy should account for:
how indexing indexing (writing) is done. If there's heavy indexing, you need to make sure all nodes participate (i.e. write similar amounts of data on the same number of shards), otherwise there will be bottlenecks
how data is queried. If queries often refer to a single user's data, it's useful to have data already broken down by user (index per user or routing by user)
total number of shards. The more shards, nodes and fields you have, the bigger the cluster state. If the cluster state size becomes large (e.g. larger than a few 10s of MB), it becomes harder to keep in sync on all nodes, leading to cluster instability. As a rule of thumb, you'll want to stay within a few 10s of thousands of shards in a single Elasticsearch cluster
In practice, I've seen the following designs:
one index per fixed time interval. You'll see this with logs (e.g.
Logstash writes to daily indices by default)
one index per time interval, rotated by size. This maintains constant index sizes even if write throughput varies
one index "series" (either 1. or 2.) per user. This works well if you have few users, because it eliminates filtering. But it won't work with many users because you'd have too many shards
one index per time interval (either 1. or 2.) with lots of shards and routing by user. This works well if you have many users. As Mahesh pointed out, it's problematic if some users have lots of data, leading to uneven shards. In this case, you need a way to reindex big users into their own indices (see 3.), and you can use aliases to hide this logic from the application.
I didn't see a design with one index per user and routing by date interval yet. The main disadvantage here is that you'll likely write to one shard at a time (the shard containing today's hash). This will limit your write throughput and your ability to balance writes. But maybe this design works well for a high-but-not-huge number of users (e.g. 1K), few writes and lots of queries for limited time intervals.
BTW, if you want to learn more about this stuff, we have an Elasticsearch Operations training, where we discuss a lot about architecture, trade-offs, how Elasticsearch works under the hood. (disclosure: I deliver this class)
I work with Couchbase DB and I want to index part of its data on Elastic Search (ES).
The data from Couchbase should be synced, i.e. if the document on CB changes, it should change the document on ES.
I have several questions about what is the best way to do it:
What is the best way to sync the data ? I saw that there is a CB plugin for ES (http://www.couchbase.com/couchbase-server/connectors/elasticsearch), but it that the recommended way ?
I don't want to store all the CB document on ES, but only part of it, e.g. some of the fields I want to store and some not - how can I do it ?
My documents may have different attributes and the difference may be big (e.g. 50 different attributes/fields). Assuming I want to index all these attributes to ES, will it effect the performance because I have a lot of fields indexed ?
10x,
Given the doc link, I am assuming you are using Couchbase and not CouchDB.
You are following the correct link for use of Elastic Search with Couchbase. Per the documentation, configure the Cross Data Center Replication (XDCR) capabilities of Couchbase to push data to ES automatically as mutations occur.
Without a defined mapping file, ES will create a default mapping. You can provide your own mapping file (or alter the one it generates) to control which fields get indexed. Refer to the enabled property in the ES documentation at http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/mapping-object-type.html.
Yes, indexing all fields will affect performance. You can find some performance management tips for the Couchbase integration at http://docs.couchbase.com/couchbase-elastic-search/#managing-performance. The preferred approach to the integration is perform the search in ES and only get keys back for the matched documents. You then make a multiget call against the Couchbase cluster to retrieve the document details themselves. So while ES will index many fields, you do not store all fields there nor do you retrieve their values from ES. The in-memory multiget against Couchbase is the fastest way to retrieve the matching documents, using the IDs from ES.
Lot of questions..!
Let me answer one by one:
1)The best way and already available solution to use river plugin to dynamically sync the data.And also it ll index the changed document alone..It ll help a lot in performance.
2)yes you can restrict the field to be indexed in river plugin. refer
The documents of plugin is available in couchbase website itself.
Refer: http://docs.couchbase.com/couchbase-elastic-search/
Github river is still in development.,but you can use the code and modify as your need.
https://github.com/mschoch/elasticsearch-river-couchbase
3)If you index all the fields, yes there will be some lag in performance.So better to index the needed fields alone. if you need to store some field just to store, then mention in mapping as not analyzed to specific.It will decrease indexing time and also searching time.
HOpe it helps..!
You might find this additional explanation regarding Don Stacy's answer to question 2 useful:
When replicating from Couchbase, there are 3 ways in which you can interfere with Elasticsearch's default mapping (before you start XDCR) and thus, as desired, not store certain fields by setting "store" = false:
Create manual mappings on your index
Create a dynamic template
Edit couchbase_template.json
Hints:
Note that when we do XDCR from Couchbase to Elasticsearch, Couchbase wraps the original document in a "doc" field. This means that you have to take this modified structure into account when you create your mapping. It would look something like this:
curl -XPUT 'http://localhost:9200/test/couchbaseDocument/_mapping' -d '
{
"couchbaseDocument": {
"_source": {
"enabled": false
},
"properties": {
"doc": {
"properties": {
"your_field_name": {
"store": true,
...
},
...
}
}
}
}
}'
Documentation: https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping.html
Including/Excluding fields from _source: https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-source-field.html
Documentation: https://www.elastic.co/guide/en/elasticsearch/reference/2.0/dynamic-templates.html
https://forums.couchbase.com/t/about-elasticsearch-plugin/2433
https://forums.couchbase.com/t/custom-maps-for-jsontypes-with-elasticsearch-plugin/395