AWS Databases

 


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RDS vs Aurora DB

 1) Backtrack/Point in Time Restore (PITR) RDS Point in time restore is restore is supported, but it requires another RDS instance to be launched. Aurora Backtracks lets you quickly rewind the DB cluster to a specific point in time, without having to create another DB cluster. 2) Engine Options - Differences RDS - No concept of Global DB. Aurora - Global DB, Primary DB in one region and secondary DB in another region. 3) Compatibility with DB engines Aurora is compatible with two DBMSs namely PostgreSQL and MySQL. It is compatible with PostgreSQL 9.6.1 and MySQL 5.6. This means that you can run your existing database tools and applications on Aurora without any modifications.  On the other hand, Amazon RDS requires you to use AWS Database Migration Service to migrate from EC2-hosted or on-premises databases such as MySQL, PostgreSQL, MariaDB, Microsoft SQL Server, and Oracle. 4) Failover In RDS, Failover to read replica is done manually, which could lead to data loss. You can ...
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Find Loop in a Linked List

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 Problem Statement In this problem, we are given a linked list with a loop. We have to find the first node of the loop in the linked list. Problem Statement Understanding Let’s try to understand the problem statement with the help of examples. Suppose the given list is: According to the problem statement, we need to find the starting node of the loop. From the linked list, we can see that there is a loop in the linked list starting at node with value 3 and containing 3 nodes 3, 5, and 7. The last node of the loop points back to the first node of the loop. As node with value 3 is the first node of the loop, so we will return 3 as output. Approach and Algorithm (Floyd’s Cycle Detection) Our approach will be simple: 1) Firstly, we have to detect the loop in the given linked list. For detecting a loop in any linked list, we know the most efficient algorithm is the  Floyd Cycle detection Algorithm . 2) In Floyd's cycle detection algorithm, we initialize 2 pointers,  slow ...
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Optional Vs Null Check

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The purpose of Optional is not to replace every single null reference in your codebase but rather to help design better APIs in which—just by reading the signature of a method—users can tell whether to expect an optional value. In addition, Optional forces you to actively unwrap an Optional to deal with the absence of a value; as a result, you protect your code against unintended null pointer exceptions. String version = computer.getSoundcard().getUSB().getVersion(); This code can lead to NullPointerException. Handle NullPointerException - This code looks ugly. String version = "UNKNOWN"; if(computer != null){   Soundcard soundcard = computer.getSoundcard();   if(soundcard != null){     USB usb = soundcard.getUSB();     if(usb != null){       version = usb.getVersion();     }   } } String name = computer.flatMap(Computer::getSoundcard)                           .f...
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