I have a news site with 150,000 news articles. About 250 new articles are added daily to the database at an interval of 5-15 minutes. I understand that Solr is optimized for millions of records and my 150K won't be a problem for it. But I am worried the frequent updation will be a problem, since the cache gets invalidated with every update. In my dev server, cold load of a page takes 5-7 seconds to load (since every page runs a few MLT queries).
Will it help, if I split my index into two - An archive index and a latest index. The archive index will be updated once every day.
Can anyone suggest any ways to optimize my installation for a constantly updating index?
Thanks
My answer is: test it! Don't try to optimize yet if you don't know how it performs. Like you said, 150K is not a lot, it should be quick to build an index of that size for your tests. After that, run a couple of MLT queries from a different concurrent threads (to simulate users) while you index more documents to see how it behaves.
One setting that you should keep an eye on is auto-commit. Since you are indexing constantly, you can't commit at each document (you will bring Solr down). The value that you will choose for this setting will let you tune the latency of the system (how many times it takes for new documents to be returned in results) while keeping the system responsive.
Consider using mlt=true in the main query instead of issuing per-result MoreLikeThis queries. You'll save the roundtrips and so it will be faster.
Related
The problem I am facing with couchDB is whenever I hit any database for the first time, it fetches quite slowly, though the speed is increased from the second time. Is there any workaround we can do so that this glitch gets removed for the first time as well?
Secondary indexes in CouchDB are not updated during document write operations (doc). So the delay is because the view is actually generated for the first time.
For CouchDB 3.x: look into tuning background indexing
For CouchDB 2.x and before: upgrade and/or prefetch your views regularly so they've been built at the moment you need them quickly available
Ah, and if you're doing mango queries, then make sure required indexes are defined in the first place so you're not rescanning the DB every time :)
What is the best practice for running a database-query after any document in a collection become of certain age?
Let's say this is a node.js web-system with mongoDB, with a collection of posts. After a new post is inserted, it should be updated with some data after 60 minutes.
Would a cron-job that checks all posts with (age < one hour) every minute or two be the best solution? What would be the least stressing solution if this system has >10.000 active users?
Some ideas:
Create a second collection as a queue with a "time to update" field which would contain the time at which the source record needs to be updated. Index it, and scan through looking for values older than "now".
Include the field mentioned above in the original document and index it the same way
You could just clear the value when done or reset it to the next 60 minutes depending on behavior (rather than inserting/deleting/inserting documents into the collection).
By keeping the update-collection distinct, you have a better chance of always keeping the entire working set of queued updates in memory (compared to storing the update info in your posts).
I'd kick off the update not as a web request to the same instance of Node but instead as a separate process so as to not block user-requests.
As to how you schedule it -- that's up to you and your architecture and what's best for your system. There's no right "best" answer, especially if you have multiple web servers or a sharded data system.
You might use a capped collection, although you'd run the risk of potentially losing records needing to be updated (although you'd gain performance)
I have a site search I would like to implement using Solr. Unfortunately, I also have a lot of frequently updated dynamic data in my MySQL database from cron jobs, which I would also like to be searchable.
I would automatically assume that constantly updating records in Solr is not a good idea so is there a workable solution to give me the text-search power of Solr as well as being able to filter based on these frequently updated fields?
I think this depends what "frequently" means and how long your tolerated Solr-lag is.
In my case, i update Solr twice every minute, which works fine.
..based on an MySql DB with some hundred updates a Minute.
In this situation it's important NOT to run an optimize on every Solr update/commit. Better run an optimize every n hoers.
So finally, all the new MySQL stuff will be visible in Solr with max. 30 sec. delay.
It depends on your situation if this is acceptable.
I have a Solr index with document fields something like:
id, body_text, date, num_upvotes, num_downvotes
In my application, a document is created with some integer id and some body_text (500 chars max). The date is set to the time of input, and num_upvotes and num_downvotes begin at 0.
My application gives users the ability to upvote and downvote the content mentioned above, and the reason I want to keep track of this in Solr instead of just the DB is that I want to be able to consider the number of upvotes and downvotes into my search.
This is a problem because you can't simply update a solr document (i.e. increment number of up_votes) and you must replace the entire document, which is probably fairly inefficient considering it would require hitting my DB to grab all the relevant data again.
I realize the solution may require a different layout of data, or possibly multiple indexes (although I don't know if you can query/score across solr cores).
Is anyone able to offer any recommendations on how to tackle this?
A solution that I use in a similar problem is to update that information in database and do SOLR Updates/Inserts every ten minutes using the documents that were modified since the last update.
Also every night, when I don't have much traffic I do index optimize.
After each import I set up some warm-up queries in SOLR config.
In my SOLR index I have around 1.5 milion documents,each document has 24 fields, and around 2000 characters in the entire document.
I update the index every 10 minutes around 500 documents ( without optimizing the index ), and I do around 50 warmup queries comprised of most common facets, most used filter queries and free text search.
I don't get negative impact on performance. ( at least it is not visible ) - my queries run average in 0.1 seconds. ( before doing update at every 10 minutes average queries were 0.09 seconds)
LATER EDIT:
I didn't encounter any problems during this updates. I allways take the documents from database and insert them with a Unique key to SOLR. If the document exist in SOLR it is replaced ( this is what I mean by update).
It never takes more than 3 minutes to update SOLR. Actually I am doing 10 minutes break after each update. So I start the update of the index, I wait for it to finish, and then I wait another 10 minutes to start again.
I did not look on the performance over the night, but for me it is not relevant, as I want to have fresh information of data during the users visits peaks.
The Join feature would help you here. Then you could store the up/down votes in a separate document.
The bad news is that you need to wait until Solr 4 unless you're comfortable running with a trunk build.
If you are only going to be updating the up/down votes. Instead of going back to the database, just use the appropriate Solr Client for your application and pull the document from the index, set the up/down values as needed and then reinsert the document back into the index.
There is no solution to your problem within SOLR. You have a database problem and you are trying to solve it with a search engine.
The best way to deal with this is to keep a redis database that records the document id from SOLR and the up/down vote counts. Then your app can merge the data from both sources before displaying.
I am new to CouchDB, but that is not related to the problem. The question is simple, yet not clear to me.
For example: Boris was on the site 5 seconds ago and viewing his profile Ivan sees it.
How to correctly implement this feature (users last-access time)?
The problem is that, if we update users profile document in CouchDB, for ex. property last_access_time, each time a page is refreshed, than we will have the most relevant information (with MySQL we did it this way), but on the other hand, we will have _rev of the document somewhere about 100000++ by the end of the day.
So, how do you do that or do you have any ideas?
This is not a full answer but a possible optimization. It will work in addition to any other answers here.
Instead of storing the latest timestamp, update the timestamp only if it has changed by e.g. 5 seconds, or 60 seconds.
Assume a user refreshes every second for a day. That is 86,400 updates. But if you only update the timestamp at 5-second intervals, that is 17,280; for 60-seconds it is 1,440.
You can do this on the client side. When you want to update the timestamp, fetch the current document and check the old timestamp. If it is less than 5 seconds old, don't do anything. Otherwise, update it normally.
You can also do it on the server side. Write an _update function in CouchDB, which you can query like e.g. POST /db/_design/my_app/_update/last-access/the_doc_id?time=2011-01-31T05:05:31.872Z. The update function will do the same thing: check the old timestamp, and either do nothing, or update it, depending on the elapsed time.
If there was (a large) part of a document that is relatively static, and (a small) part that is highly dynamic, I would consider splitting it into two different documents.
Another option might be to use something more suited to the high write throughput of small pieces of data of that nature such as Redis or possibly MongoDB, and (if necessary) have a background task to occasionally write the info to CouchDB.
CouchDB has no problem with rapid document updates. Just do it, like MySQL. High _rev is no problem.
The only thing is, you have to be responsible about your couch from day 1. All CouchDB users must do this anyway, however you may have to do it sooner. (Applications with few updates have lower risk of a full disk, so developers can postpone this work.)
Poll your database and run compaction if it needs it (based on size, document count, seq_id number)
Poll your views and run compaction too
Always have enough disk capacity and i/o bandwidth to support compaction. Mathematical worst-case: you need 2x the database size, and 2x the write speed; however, most applications require less. Since you are updating documents, not adding them, you will need way less.