Distributed percolator in elasticsearch

Talk at Amsterdam meetup about the redesigned distributed percolator in Elasticsearch .

Transcript

1. Martijn van Groningen @mvgroningen Percolator Thursday, September 5, 13
2. Topics • What is percolator? • Redesigned percolator • New percolator features • How does the percolator work? Thursday, September 5, 13
3. Percolator? coffee OR pots Title : Coffee percolator Body : A coffee percolator is a type of pot used to brew coffee by continually cycling the boiling or nearly-boiling brew through ... Title : Coffee percolator Body : A coffee percolator is a type of pot used to brew coffee by continually cycling the boiling or nearly-boiling brew through ... Title : Coffee percolator Body : A coffee percolator is a type of pot used to brew coffee by continually cycling the boiling or nearly-boiling brew through ... Title : Coffee percolator Body : A coffee percolator is a type of pot used to brew coffee by continually cycling the boiling or nearly-boiling brew through ... 1. Coffee percolator 2. Plain old telephone service (pots) ... Hits Query Documents Thursday, September 5, 13
4. Percolator? coffee OR pots Title : Coffee percolator Body : A coffee percolator is a type of pot used to brew coffee by continually cycling the boiling or nearly-boiling brew through ... 1. Coffee OR pots 2. boiling AND brew ... Matches Document Queries boiling AND brew other AND stuff Thursday, September 5, 13
5. Percolator? • Reversed search • Document becomes a query and a query becomes a document. • Queries need to be stored. • matches != hits Because hits has relevancy whereas matches have not. Thursday, September 5, 13
6. Percolator, but how? • Search request: • Queries are defined in JSON. • But so are documents! curl -XPOST 'localhost:9200/my-index/_search' -d '{ "query" : { "match" : { "body" : "coffee" } } }' Thursday, September 5, 13
7. Percolator, but how? • Indexing a query (<=0.90): • Any query can be indexed as a document. Plus any arbitrary data curl -XPUT 'localhost:9200/_percolator/my-index/my-id' -d '{ "query" : { "match" : { "body" : "coffee" } }, "click_id" : 12 }' Thursday, September 5, 13
8. Percolator, but how? • Indexing a query: • Path structure index: _percolator is a reserved index for queries. type: The index to register a query to. id: The unique identifier for a query. curl -XPUT 'localhost:9200/_percolator/my-index/my-id' -d '{ "query" : { "match" : { "body" : "coffee" } }, "click_id" : 12 }' Thursday, September 5, 13
9. Percolator, but how? • Percolate api (<=0.90): • All queries registered to ‘my-index’ are consulted. curl -XPUT 'localhost:9200/my-index/my-type/_percolate' -d '{ "doc" : { "title" : "Coffee percolator", "body" : "A coffee percolator is a type of ..." } }' Thursday, September 5, 13
10. Percolator, but how? • Percolate api response (<=0.90): • A simple list of query ids. • Also the percolate api work in realtime. { "ok" : true "matches" : ["my-id",...] } Thursday, September 5, 13
11. Percolation in the wild Thursday, September 5, 13
12. Alerting use case • Store and register queries that monitor data. End users can define their alerts via application. • Execute the percolate api right after indexing. No need to wait - percolator works in realtime. • Examples: Price monitor, News alerts, Stock alerts, Weather alerts Thursday, September 5, 13
13. Alerting use case curl -XPUT 'localhost:9200/_percolator/prices/user-1' -d '{ "query" : { "bool" : [ { "range" : { "product.price" : { "lte" : 500 } } }, { "match" : { "product.name" : "my led tv" } } ] } }' Triggered by user adding an user alert: Thursday, September 5, 13
14. Percolator - alerting use case curl -XPOST 'localhost:9200/prices/price/_percolate' -d '{ "doc" : { "product" : { "name" : "my led tv", "price" : 499 } } }' Then when new TVs are added: Thursday, September 5, 13
15. Pricing use case • Store all users’ queries of a specific time frame Last week’s, last month’s queries. • Provide feedback to advertisement owner. Execute percolate api while editing the ad. • Examples: Real estate, car sales or any other market place. Thursday, September 5, 13
16. Contextual ads use case • Store advertisement as queries. • On page display percolate document against the stored advertisements. • Examples: Gmail Thursday, September 5, 13
17. Classification use case • Store queries that can identify patterns in your documents. • Percolate a document before indexing it. Enrich the document with the queries it matches with. • Examples: Automatically tag documents, geo tag documents and ways to automatically categorize documents. Thursday, September 5, 13
18. Distributed Percolator Thursday, September 5, 13
19. Percolator - redesign • The _percolator index can only have one primary shard. Node 1 p1 Node 2 p1 Node 3 p1 C Percolate ? ? ? ? ? ? ? ? ? Thursday, September 5, 13
20. Percolator - redesign • The redesigned percolator has no dedicated reserved _percolator index. • Instead the redesigned percolator has a _percolator type / mapping. • Any index can become a percolator index. Without any restrictions on (sharding) settings. Thursday, September 5, 13
21. Percolator - redesign • Because _percolator index has been replaced by _percolator type: • Queries and your data coexist in the same index. Percolator shares the settings of the index it sits in. • Or have a number dedicated percolator indices. Thursday, September 5, 13
22. Percolator - redesign • Redesigned percolator is fully distributed. Node 1 a1 Node 2 a1 C Percolate a2 a2 Thursday, September 5, 13
23. Percolator - redesign • Indexing a query: • Path structure index: The index to hold the query. type: The reserved _percolator type. id: The unique identifier for a query. curl -XPUT 'localhost:9200/my-index/_percolator/my-id' -d '{ "query" : { "match" : { "body" : "coffee" } }, "click_id" : 12 }' Thursday, September 5, 13
24. • Percolate api remains similar, but: Fully multi tenant: Full alias support: And routing support. Percolator - redesign curl -XGET 'localhost:9200/my-index1,my-index2/my-type/_percolate' -d '{ "doc" : { "title" : "Coffee percolator", "body" : "A coffee percolator is a type of ..." } }' curl -XGET 'localhost:9200/my-alias/my-type/_percolate' -d '{ "doc" : { "title" : "Coffee percolator", "body" : "A coffee percolator is a type of ..." } }' Thursday, September 5, 13
25. Percolator - redesign • Percolate api response: { "took" : 19, "_shards" : { "total" : 2, "successful" : 2, "failed" : 0 }, "count" : 4, "matches" : [ { "_index" : "my-index1", "_id" : "my-id" }, { "_index" : "my-index2", "_id" : "my-id" }, ... ] } Thursday, September 5, 13
26. Percolator - how does it work? • Each shard holds a Collection of parsed queries in memory. • The queries are also stored on the shard (Lucene index) • The collection of queries get updated by every index, create, update or delete operation in realtime. Thursday, September 5, 13
27. Percolator - how does it work? • During percolating the document to be percolated gets indexed into an in memory index. • All shard queries are executed against this one document in memory index. Shard level execution time is linear to the amount queries to evaluate. • After all queries have been evaluated the in memory index gets cleaned up. Thursday, September 5, 13
28. Distributed percolator • Percolate api executes the request in parallel on all shards. • Use routing and multi tenancy to reduce the amount of queries to evaluate. - Routing will reduce the amount of shards. - More indices (and therefore more shards) reduces the amount of queries per shard. Thursday, September 5, 13
29. Distributed percolator • No routing / partitioning Node 1 a1 Node 2 a1 C Percolate a2 a2 a3 a3 Thursday, September 5, 13
30. Distributed percolator • Percolating with routing: Node 1 a1 Node 2 a1 C Percolate, but route with XYZ a2 a2 a3 a3 Thursday, September 5, 13
31. Node 1 Distributed percolator • Percolating based on location partitioning in different indices. a1 Node 2 a1 C a2 a2 b1 b1 b2 index a = EU queries index b = NA queries b2 Thursday, September 5, 13
32. Percolator features Thursday, September 5, 13
33. Feature - percolate existing doc • Percolating a newly indexed document is very common pattern. curl -XGET 'localhost:9200/my-index1/my-type/1/_percolate' curl -XGET 'localhost:9200/my-index1/my-type/1/_percolate?percolate_index=my-index2' my-index1 is both percolate and source index: my-index2 contains the queries to evaluate: and my-index1 contains the document to percolate Thursday, September 5, 13
34. Feature - count api curl -XPUT 'localhost:9200/my-index1/my-type/_percolate/count' -d '{ "doc" : { "title" : "Coffee percolator", "body" : "A coffee percolator is a type of ..." } }' { "took" : 8, "_shards" : { "total" : 2, "successful" : 2, "failed" : 0 }, "count" : 5 } Response: Count api: curl -XPUT 'localhost:9200/my-index1/my-type/1/_percolate/count' Count existing doc api: Thursday, September 5, 13
35. Feature - filtering curl -XGET 'localhost:9200/my-index1/my-type/_percolate/count' -d '{ "doc" : { "title" : "Coffee percolator", "body" : "A coffee percolator is a type of ..." }, "query" : { "term" : {"click_id" : "43"} } }' Filtering by query: curl -XGET 'localhost:9200/my-index1/my-type/_percolate/count' -d '{ "doc" : { "title" : "Coffee percolator", "body" : "A coffee percolator is a type of ..." }, "filter" : { "term" : {"click_id" : "43"} } }' Filtering by filter: Thursday, September 5, 13
36. Feature - sorting / scoring • Build on top on the query support. • Sorting based on percolator query fields. Document being percolated isn’t scored! • Three new options: • size The amount of matches to return (required with sort) • sort Whether to sort based on query. • score Just include score, but don’t sort • Like the query / filter support not realtime. Thursday, September 5, 13
37. Feature - sorting / scoring • Sorting support works nicely with function score query. curl -XGET 'localhost:9200/my-index1/my-type/_percolate' -d '{ "doc" : { ... }, "query" : { "function_score" : { "query" : { "match_all": {}}, "functions" : [ { "exp" : { "create_date" : { "reference" : "2013/08/14", "scale" : "1000d" } } } ] } } "sort" : true, "size" : 10 }' Field in query Thursday, September 5, 13
38. Feature - sorting / scoring { "took": 2, "_shards": { "total": 5, "successful": 5, "failed": 0 }, "total": 2, "matches": [ { "_index": "my-index", "_id": "2", "_score": 0.85559505 }, { "_index": "my-index", "_id": "1", "_score": 0.4002574 } ] } • Response: Thursday, September 5, 13
39. Feature - highlighting curl -XPUT 'localhost:9200/my-index/_percolator/1' -d '{ "query": { "match" : { "body" : "brown fox" } } }' curl -XPUT 'localhost:9200/my-index/_percolator/2' -d '{ "query": { "match" : { "body" : "lazy dog" } } }' • Lets index two queries: Thursday, September 5, 13
40. Feature - highlighting • The size option is required. • All highlight options are supported. curl -XGET 'localhost:9200/my-index/my-type/percolate' -d '{ "doc" : { "body" : "The quick brown fox jumps over the lazy dog" }, "highlight" : { "fields" : { "body" : {} } }, "size" : 5 }' Thursday, September 5, 13
41. Feature - highlighting { ... "total": 2, "matches": [ { "_index": "my-index", "_id": "1", "highlight": { "body": [ "The quick <em>brown</em> <em>fox</em> jumps over the lazy dog" ] } }, { "_index": "my-index", "_id": "2", "highlight": { "body": [ "The quick brown fox jumps over the <em>lazy</em> <em>dog</em>" ] } } ] } Thursday, September 5, 13
42. Feature - multi percolate • Combine multiple percolate requests into a single request. {"percolate" : {"index" : "my-index", "type" : "my-tweet"}} {"doc" : {"title" : "coffee percolator"}} {"percolate" : "index" : "my-index", "type" : "my-type", "id" : "1"} {} {"count" : {"index" : "my-index", "type" : "my-type"}} {"doc" : {"title" : "coffee percolator"}} {"count" : "index" : "my-index", "type" : "my-type", "id" : "1"} {} curl -XGET 'localhost:9200/_mpercolate' --data-binary @requests.txt; echo requests.txt: Request: Thursday, September 5, 13