How do you ensure consistency in a distributed database?

1 Answer

1. First is to take the lock before writing anything to the database or caching system. This ensures read and write lock. This includes master server as well.
2. Secondly, if replication fails then there is the added complex layer of rollovers. This ensures that data is consistent if not then it is not applied.

What is the need of consistency in distributed system?

Consistency in Distributed Systems: Consistency in distributed systems means every node / replica has the same view of data at a given point in time irrespective of whichever client has updated the data.

How eventual consistency is achieved?

Eventual Consistency is a guarantee that when an update is made in a distributed database, that update will eventually be reflected in all nodes that store the data, resulting in the same response every time the data is queried.

Is consistency a challenge in distributed computing?

Yet, replication itself gives birth to another challenge known as the consistency in distributed systems. Scalability and availability are the challenging criteria on which the replication is based upon in distributed systems which themselves require the consistency.

How does distributed cache maintain consistency?

Write-through / read-through cache And cache is responsible of synchronously write to the data store. It doesn’t say anything about reads. Clients can do look-aside reads or read-through. Read-through cache means for reads, client reads directly from cache.

Why is consistency important while replicating nodes in distributed systems?

Strong consistency is where each read of data item x is guaranteed to see the latest write to x (across all data stores). Strong consistency allows you to program as if the underlying data wasn’t replicated.

What are the problems of clock synchronization in distributed operating systems?

Clock inaccuracies cause serious problems and troublesome in distributed systems. The clocks of different processors need to be synchronized to limit errors. This is to have an efficient communication or resource sharing. Hence the clocks need to be monitored and adjusted continuously.

Why NoSQL is not consistent?

To answer the actual question directly: “Why are nosql databases not acid compliant” is because they weren’t designed to be. ACID is a lot of work and requries lots of resources in the machine, but even Google are being forced to go back to ACID and SQL!

Is Cassandra eventually consistent?

Meeting the requirements of performance, reliability, scalability and high availability in production Cassandra is an eventually consistent storage system. Eventually consistent implies that all updates reach all replicas eventually.

What are the different problems encountered in a distributed data system?

Distributed database allows to end worker to store and retrieve data anywhere in the network where database is located, during storing and accessing any data from distributed database through computer network faces numerous difficulties happens e.g. deadlock, concurrency and data allocation using fragmentation.

What is cache consistency problem?

The Cache Coherence Problem is the challenge of keeping multiple local caches synchronized when one of the processors updates its local copy of data which is shared among multiple caches. This cache miss forces the second core’s cache entry to be updated.

Is data in cache always consistent?

In general, any data cached in the heap is always consistent in that heap. For example, if one thread gets and modifies a cached element, another thread that then gets that element sees the change as long as all activity takes place in that heap.

What is a valid timestamp data expression?

A valid timestamp data expression consists of a date and a time, followed by an optional BC or AD. In this case, a valid timestamp data expression consists of a date and a time, followed by a time_zone expression concatenated with a ‘+/-’ sign based on the position of the time zone with respect to ‘GMT’ and finally followed by an optional BC or AD.

What is the use of timestamp in MySQL?

SQL timestamp is a data type and a function that is used to store and work with data values in date and time formats, sometimes along with time zones and AD/BCs. They are very helpful when we have operations all over the world.

What is the storage size of the timestamp?

The timestamp has a storage size of 8 bytes that can accept date and time values ranging from 4713 BC and 294276 AD and provides a resolution of 1 microsecond or 14 digits.

What is timestamptz in PostgreSQL?

For example, in PostgreSQL, we have a “timestamptz” data type that takes care of time zone changes as well. Timestamptz data type also has a storage size similar to a timestamp of 8 bytes that can accept date and time values ranging from 4713 BC and 294276 AD and provides a resolution of 1 microsecond or 14 digits.