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I have a question regarding Solr replica how to create and what is the different way to create in solr and please explain and elaborate to simple way so I can understand because I am new to solr .
Replicas are exact copies of your shards and this will actually provide redundancy. To achieve high-availability/fault-tolerant behavior, every node of the cluster must have a replica of every collection.
When you create a collection, using the replicationFactor parameter you can specify the number of replicas to be created for each shard.
Example:
http://localhost:8983/solr/admin/collections?action=CREATE&name=collectionName&numShards=number&replicationFactor=number
Here is an example command to add a replica:
http://localhost:8983/solr/admin/collections?action=ADDREPLICA&collection=collectionName&shard=shard1&node=localhost:8983_solr
In the Solr documentation, you can find the ADDREPLICA parameters to use, for example the type parameter. In fact, there are 3 types of replicas; the default is NRT(Near real time) replicas, eligible to become the leader and are the only ones supporting soft commits.
Also, Solr provides a way to automatically add replicas for a collection when the number of active replicas drops below the replication factor specified at the time of the creation of the collection.
N.B. The autoscaling framework in its current form is deprecated and will be removed in Solr 9.0.
Depending on the version of Solr you are using, here you can find the relative reference guide.
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I am using redis to store highly requested info, but I want to store less-requested stuff in a list/set on the disk. I have been looking around with no luck. Memcached, Riak etc. don't seem to have list/set datatypes. Is there a database that have those features?
Thanks.
Run another Redis instance and configure it with AOF on. Append-only file.
You can read more about it here:
http://redis.io/topics/persistence
Scroll half way down, there is alot of good information on it.
Append-only file
Snapshotting is not very durable. If your computer
running Redis stops, your power line fails, or you accidentally kill
-9 your instance, the latest data written on Redis will get lost. While this may not be a big deal for some applications, there are use
cases for full durability, and in these cases Redis was not a viable
option. The append-only file is an alternative, fully-durable strategy
for Redis. It became available in version 1.1. You can turn on the AOF
in your configuration file: appendonly yes From now on, every time
Redis receives a command that changes the dataset (e.g. SET) it will
append it to the AOF. When you restart Redis it will re-play the AOF
to rebuild the state.
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I'm looking for an efficient key-value distributed persistent database.
I've look into Redis, but it only support hashes with up to $2^{32}$ keys, which is not enough for my application
I've look into Memcached, but it is not designed for long-term persistence, it is designed for keys-value pairs to expire after a while
I've look into BerkeleyDB, but does not support a client-server paradigm, it is basically a in-app storage engine
I've look into HyperTable, but is not really row-oriented, you cannot edit existing rows unless you want to hack the timestamps, and after a key + timestamp is deleted, it cannot be reinserted. Also, the only supported value type are strings, if you want to store floats or complex objects you need to serialize into a string and then deserialize
I've look into MongoDB, which is very flexible, but it has suffered from very important performance and scalability issues that haven't been addressed in the last two years. They are summarized in this blog post.
I'm going to look next into Cassandra and Riak, and as you see i'm quickly running out of real options
What other databases are there that can fit the description i've outlined above?
Take a look at CouchDB. http://guide.couchdb.org/draft/why.html
It is a non-relational database, open-source, distributed (incremental, bidirectional replication), schema-free. Data is stored in documents formatted as JSON. It has robust persistence and is a distributed key value database.
Take a look at http://code.google.com/p/fastdht
It is a high performance distributed hash table based on Berkeley DB.
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I'm pretty new to CouchDB. I have googled without finding a database viewer for CouchDB.
How do you view a CouchDB database without manipulating the raw HTTP messages ?
Ideally, the tool would meet the following requirements :
Cross-platform (Windows or Linux mainly)
Desktop application or Web application
Allow editing of documents, databases etc
There is built-in web application that allows you to manage CouchDB instance -- http://guide.couchdb.org/draft/tour.html#welcome
And your question is very ambiguous. You ask for the web application as option but without "a classic browser" you cannot use it.
In case you don't find Futon very intuitive, please checkout CouchDB Query Explorer. The tool is aimed at providing an intuitive approach to configure & use. Define your own fields & filters. Querying is as simple as selecting one or more filters. For more information please visit here
couchdb
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Are there any databases, in either the SQL or NoSQL worlds, that support protocol buffers? (Support could mean various things, but hopefully would include being able to index on fields in protocol buffers.)
ProfaneDB: http://profanedb.gitlab.io
"ProfaneDB is a gRPC interface between Protocol Buffers and RocksDB"
P.S:
Though the question was asked 10 years ago I still find it very relevant, specially with the ascension of gRPC. Hope that can be of help.
I am not aware of any (not that they don't exist, I just don't know about them), but perhaps it is worth discussing an alternate strategy and the pros and cons.
Typically you would want to store a serialized version of your protocol buffer, indexed by some particular key (a unique identifier, perhaps). You could then build secondary indexes for other interesting fields that point to that unique identifier. The idea is that you would want explicit indexes like this to scale beyond what a system that provides arbitrary indexes. This obviously opens up a world of new problems (such as stale arbitrary indexes).
Here is a project I found: https://github.com/google/mysql-protobuf
It's sql that speaks protobuf, looks promising but last commit was in mid March 2016.
ClickHouse lately added support for protobuf messages.
Cloud Spanner would provide native support for protobufs.
https://cloud.google.com/spanner/
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We are currently in the process of solidifying a database change management process.
We run MySql 5 running on RedHat 5. I have selected LiquiBase as the tool because it's open source and allows us to expand its functionality later if needed. It also seems to be one of the few free projects that are still active. Has anyone here had any experience using LiquiBase or other Db versioning tools?
Company Background: We are an SaaS company providing a 7/24 hosted application. There are dozens of instances running different versions of the same database and we need a way to manage the deploy process as it's starting to get out of control. The databases have hundreds of tables and we typically do releases once every 3 months.
I may be biased since I started LiquiBase, but I have been using it in production environments for several years and there have been many, many times where releases would have been a nightmare without it. LiquiBase has evolved to be very flexible and powerful and I have not ran into a situation that it was not able to handle (in one way or another) for quite some time.
The last code release contained of a project I am working on using LiquiBase contained a major database refactoring with hundreds of database changes and needed to be applied to a variety of installations that had different starting points for the database. When we did the release, the databases updated without any problems.
Doctrine, a PHP ORM/DBAL offers Migrations, doing what you want.
The Doctrine migration package allows
you to easily update your production
databases through a nice programmatic
interface. The changes are done in a
way so that your database is versioned
and you can walk backwards and
forwards through the database
versions.