Can I upgrade my slave from 5.6 to 5.7 and connect more masters to it? When upgrading so that the master version is lower/earlier than the slave version there is always a large risk it will not work. This is because newer versions may have made incompatible changes that means the older version will not be able to process or understand that change in the newer version. However, there is always a chance that it will work, but it is always recommended that if you want to go this way, attempt it … [Read more...] about MySQL Interview Questions : Multi-source Replication in MySQL Server
Interview Questions
Linux Interview Questions – Basic File and Directory Permissions
What are Basic Linux File permissions? Linux, like UNIX, is a multi-user system, and file permissions are one way the system protects against malicious tampering. One way to gain entry when you are denied permission is to su to root. Keep in mind, whoever knows the root password has complete access. But switching to the superuser is not always convenient or recommended since it is easy to make mistakes and alter important configuration files as the superuser. All files and directories are … [Read more...] about Linux Interview Questions – Basic File and Directory Permissions
Oracle Database Interview Questions : Redo Logs and Archiving
What is the Redo Log? Redo Logs consist of two or more pre-allocated files that store all changes made to the database as they occur. Every instance of an Oracle Database has associated online redo logs to protect the database in case of an instance failure. Redo log files are filled with redo records. A redo record also called a redo entry, is made up of a group of change vectors, each of which is a description of a change made to a single block in the database. Redo entries record data … [Read more...] about Oracle Database Interview Questions : Redo Logs and Archiving
Interview Questions : Oracle 12c Multitenant Database Architecture
General CDB / PDB Concept in 12c Multitenant Architecture What is a pluggable database (PDB) in Multitenant Architecture? Pluggable Databases (PDBs) is new in Oracle Database 12c Release 1 (12.1). You can have many pluggable databases inside a single Oracle Database occurrence. Pluggable Databases are fully backwards compatible with an ordinary pre-12.1 database. Why would I consider using the Multitenant option? You should consider following Database Consolidation Goals to … [Read more...] about Interview Questions : Oracle 12c Multitenant Database Architecture
Linux Interview Questions : Open Files / Open File Descriptors
What is an open file? An open file may be a regular file, a directory, a block special file, a character special file, an executing text reference, a library, a stream or a network file. What is file descriptor? A file descriptor is a data structure used by a program to get a handle on a file. The most commonly known are: 0 for standard in 1 for standard out 2 for standard error Does the number of open files equal the number of open file descriptors? There is a difference in the … [Read more...] about Linux Interview Questions : Open Files / Open File Descriptors
Linux interview questions – Special permissions (SUID, SGID and sticky bit)
There are two special permissions that can be set on executable files: Set User ID (setuid) and Set Group ID (sgid). These permissions allow the file being executed to be executed with the privileges of the owner or the group. Similarly, there are two special permissions for directories: the sticky bit and the setgid bit. Below are few of the most commonly asked Linux interview questions on the special permissions like SUID, SGID and sticky bit. What is Set User ID (setuid)? SUID is a … [Read more...] about Linux interview questions – Special permissions (SUID, SGID and sticky bit)
Oracle Database interview questions – Privileges And Roles
What is a Privilege? A privilege is the right to execute a particular type of SQL statement. It can allow a user to access database objects or execute stored programs that are owned by another user or to perform system level actions. There are two types of privileges: system privileges schema object privileges What are system privileges? The system privileges are not related to a certain object. They control the ability of a user to perform system level actions such as connecting to … [Read more...] about Oracle Database interview questions – Privileges And Roles
The ultimate Linux interview questions : swap
What is swap space? Swap space in Linux is used when the amount of physical memory (RAM) is full. If the system needs more memory resources and the physical memory is full, inactive pages in memory are moved to the swap space. While swap space can help machines with a small amount of RAM, it should not be considered a replacement for more RAM. Swap space is located on hard drives, which have a slower access time than physical memory. Swap space can be a dedicated swap partition … [Read more...] about The ultimate Linux interview questions : swap
The ultimate Solaris Volume Manager (SVM) interview questions
What are the configuration files used in SVM ? /etc/lvm/md.tab 1. The file is empty by default. The file is only used when metainit command is issued by the administrator. It is configured manually. 2. It can be populated by appending the output of # metastat -p. For example #metastat -p >> /etc/lvm/md.tab. 3. It can be used to recreate all the metadevices in one go. Best used in recovery of SVM configurations. For example # metainit -a (to create all metadevices mentioned in md.tab … [Read more...] about The ultimate Solaris Volume Manager (SVM) interview questions
The ultimate Solaris zones (containers) interview questions
Basics Whats the difference between a whole root zone and a sparse root zone ? Whole root zone - Gets its own writable copy of all file systems. Thus installation takes longer time than the sparse root zone. - Also called as big zone. - Bigger disk footprint, thus consumes more disk space - To create a Whole root zone we use the option -b with create sub-command : # zonecfg -z zone01 zonecfg:zone01> create -b Sparse root zone - critical file systems like /usr, /lib, /etc, … [Read more...] about The ultimate Solaris zones (containers) interview questions