Does Cassandra support like attribute on a string. I feel like based on partition system in cassandra, this type of query is not even supported in cassandra.
If I have model post
CREATE TABLE Post (
title text PRIMARY KEY,
description text,
);
How can I search title and description for a particular string pattern.?
what are options to implement this in cassandra.?
Do I need to pull all key strings using some text analytics API from title and description and store separately in a different table ?
You're right, wildcard searches are not supported in Cassandra, given its key-value structure. A common solution people used is to use another product like Solr or Elastisearch to create indexes off of your Cassandra data.
Cassandra 3.4 and later includes support for a new type of indexing that will allow you to do partial matching and full text search. Details can be found in the DataStax documentation: Using a SSTable Attached Secondary Index (SASI).
Related
Is it possible to query items in a CQL table that exactly match a specific element in a set. For example, can we search for where tag="music" on the following table?
create table if not exists example (
website text,
uuid text,
message text,
tags set<text>,
created timestamp,
primary key ((site), uuid))
It's possible to search for elements in the collection using the CONTAINS operator (see documentation). But it will be very slow, so index on collection may help (see docs for syntax) but it's also not necessary optimal. Better solution would be something like Storage Attached Indexes from DataStax, but they aren't in the OSS Cassandra yet. Another solution could be integration of real search engine, like, Solr (known as DSE Search), or Elasticsearch (as in Elassandra).
The main thing to take into account would be to analyze the latency requirements, in some cases, it would be better to have a separate table with tag as partition key, but in this case you may have data skew as there are not so many tags, and distribution of data is not uniform.
How can I query based on only one field in UDT (Cassandra) ?
I have a UDT which contains marital status and I need data for all the married people
but when I query based on one field it gives empty output
How can I do this ?
short answer - NO, at least not in the stock Cassandra. It's possible to do using the DSE Search, but it adds its own constraints. Maybe when SAI will be implemented some day, it will support indexing of UDT fields. I don't remember if SASI supports this, but it's really not recommended to use. But even if indexing was supported, it's still bad case (maybe except SAI) for Cassandra because it will create big partitions to represent each status.
The general rule is that you need to always query by partition key, with possibility to use secondary indexes when you need to search for another field, but only inside partition. If you need to query by multiple fields that not primary keys, I would suggest to take another database, or use Elasticsearch/Solr (although they aren't very good in geo-distributed environment).
i wanna to search in cassandra database.
After much research, I found
Stratio’s Cassandra Lucene Index
Is there another way to simple search on Cassandra?
I mean a simple search query something like in Mysql
I've used this query but his conclusion was wrong
select * from users where uname > 'sa' allow filtering;
It seems to me that you'd want to perform a text search on a non PRIMARY KEY column.
If that's the case, you could use a SSTable Attached Secondary Index (SASI) that would allow to exactly search as you wrote. Specifically, you'd need to create a CONTAINS index to perform inequality searches on text fields. You need Cassandra 3.4 and later.
In SQL, we have an option to specify the LIKE operator in the where clause. Is there something like that in Cassandra? I am building a search feature for my site. All the data resides on Cassandra. So, it would be easier to search for keywords with LIKE operator.
No.You dont have such feature in cassandra. You gotto create a search engine on the data that is stored in cassandra to index the entries in cassandra may be. Cassandra serves as a container to hold your data and does not provide such features like full text search yet(I doubt if they will really as the storage is across SSTables).
If you need search capabilities on cassandra data, look no further than DSE:
http://docs.datastax.com/en/datastax_enterprise/4.7/datastax_enterprise/srch/srchIntro.html
I have a cassandra column family which has a row key like
2012-09-30-05-42-00:30:5856869
I need to query some thing like
select * from cf where key like %5856869%
Currently I am using Astyanax , is same possible in astyanax. If not, which implementation would support it.
LIKE queries are not supported in Cassandra. If you want to query based on part of a key, you'll want to use composite keys. But in this specific case, the 5856869 portion of the key would have to be the first part for you to do what you want. Remember that with Cassandra, you must write your data the way you expect to read it.
None.... you need to write index manually - this is how you handle such things in Cassandra, or you might try full text search: Cassandra full text search like