Solaris Interview Questions| Interview Questions For Solaris
What does the pkgadd command do?
How do you create a solaris package?
How do you view shared memory statistics?
How do you get system diagnostics information?
What is OBP and how do you access it?
What is LOM and how do you access it?
What is VTS?
What is an alternative to the “top” command on Solaris?
What is /etc/system for?
What does ndd do?
What does init 5 do?
What does init 0 do?
How do you boot from CD-ROM?
What is jumpstart?
How do you boot from a Network with jumpstart?
What is JASS?
What is the difference between NFS version 2 and NFS version 3?
What is RPC? Why do I need it?
Are kernel parameters tunable during runtime?
What does fmthard do?
Linux Administrator Interview Questions| Linux Interview Questions
Linux Administrator Interview Questions| Linux Interview Questions
How do you take a single line of input from the user in a shell script?
Write a script to convert all DOS style backslashes to UNIX style slashes in a list of files.
Write a regular expression (or sed script) to replace all occurrences of the letter ‘f’, followed by any number of characters, followed by the letter ‘a’, followed by one or more numeric characters, followed by the letter ‘n’, and replace what’s found with the string “UNIX”.
Write a script to list all the differences between two directories.
Write a program in any language you choose, to reverse a file.
What are the fields of the password file?
What does a plus at the beginning of a line in the password file signify?
Using the man pages, find the correct ioctl to send console output to an arbitrary pty.
What is an MX record?
What is the prom command on a Sun that shows the SCSI devices?
What is the factory default SCSI target for /dev/sd0?
Where is that value controlled?
What happens to a child process that dies and has no parent process to wait for it and what’s bad about this?
What’s wrong with sendmail? What would you fix?
What command do you run to check file system consistency?
What’s wrong with running shutdown on a network?
What can be wrong with setuid scripts?
What value does spawn return?
Write a script to send mail from three other machines on the network to root at the machine you’re on. Use a ‘here doc’, but include in the mail message the name of the machine the mail is sent from and the disk utilization statistics on each machine?
Why can’t root just cd to someone’s home directory and run a program called a.out sitting there by typing “a.out”, and why is this good?
What is the difference between UDP and TCP?
What is DNS?
What does nslookup do?
How do you create a swapfile?
How would you check the route table on a workstation/server?
How do you find which ypmaster you are bound to?
How do you fix a problem where a printer will cutoff anything over 1MB?
What is the largest file system size in solaris? SunOS?
What are the different RAID levels?
Write a script to convert all DOS style backslashes to UNIX style slashes in a list of files.
Write a regular expression (or sed script) to replace all occurrences of the letter ‘f’, followed by any number of characters, followed by the letter ‘a’, followed by one or more numeric characters, followed by the letter ‘n’, and replace what’s found with the string “UNIX”.
Write a script to list all the differences between two directories.
Write a program in any language you choose, to reverse a file.
What are the fields of the password file?
What does a plus at the beginning of a line in the password file signify?
Using the man pages, find the correct ioctl to send console output to an arbitrary pty.
What is an MX record?
What is the prom command on a Sun that shows the SCSI devices?
What is the factory default SCSI target for /dev/sd0?
Where is that value controlled?
What happens to a child process that dies and has no parent process to wait for it and what’s bad about this?
What’s wrong with sendmail? What would you fix?
What command do you run to check file system consistency?
What’s wrong with running shutdown on a network?
What can be wrong with setuid scripts?
What value does spawn return?
Write a script to send mail from three other machines on the network to root at the machine you’re on. Use a ‘here doc’, but include in the mail message the name of the machine the mail is sent from and the disk utilization statistics on each machine?
Why can’t root just cd to someone’s home directory and run a program called a.out sitting there by typing “a.out”, and why is this good?
What is the difference between UDP and TCP?
What is DNS?
What does nslookup do?
How do you create a swapfile?
How would you check the route table on a workstation/server?
How do you find which ypmaster you are bound to?
How do you fix a problem where a printer will cutoff anything over 1MB?
What is the largest file system size in solaris? SunOS?
What are the different RAID levels?
Weblogic Realtime Interview Questions| Weblogic Interview Questions
Weblogic Realtime Interview Questions| Weblogic Interview Questions
1). If two managed servers is there Same Domain is configured in both servers, but one physical server is crashed then how can you create a domain with the same configuration?
2). Give me the real time scenario to configure weight based algorithm in a cluster?
3). If some servers in cluster are running some of them are down is it deployment is possible?
4). Is it possible two different versions of the same application deploy at the same time?
5). How to recover password in weblogic?
6). How to recover boot.properties?
7). How to recover serializedini.dat, if the file is corrupted?
8). How admin server knows that the managed server is down?
9). What you can do if multicast buffer is full and how you know that?
10). What is the Max amount of information that can be saved in a session object?
11). How do u differentiate a out of memory and memory leak issue?
1). If two managed servers is there Same Domain is configured in both servers, but one physical server is crashed then how can you create a domain with the same configuration?
2). Give me the real time scenario to configure weight based algorithm in a cluster?
3). If some servers in cluster are running some of them are down is it deployment is possible?
4). Is it possible two different versions of the same application deploy at the same time?
5). How to recover password in weblogic?
6). How to recover boot.properties?
7). How to recover serializedini.dat, if the file is corrupted?
8). How admin server knows that the managed server is down?
9). What you can do if multicast buffer is full and how you know that?
10). What is the Max amount of information that can be saved in a session object?
11). How do u differentiate a out of memory and memory leak issue?
Informatica Interview Questions and Answers
Informatica Interview Questions and Answers
1=which of the following type of sources are supported for sorter transformation?
A=relational database & flat files
B= relational database & COBOL files
C= relational database & COBOL files & FLAT FILES
D= relational database ONLY
B= relational database & COBOL files
C= relational database & COBOL files & FLAT FILES
D= relational database ONLY
ANS:A
2=with which of the following the master gateway is associated?
2=with which of the following the master gateway is associated?
A=Node if you do not have high availability and domain if you do
B=node
C=domain
D=Repository
B=node
C=domain
D=Repository
ANS :C
3=which of the following is related to character sets during the repository configuration?
3=which of the following is related to character sets during the repository configuration?
A=Codepage
B=none of the listed options
C=Char type
D=Code char
ANS:A
4=In which of the following tab of Domain in Administration console you can view or modify the user permission?
A=Permission
B=user activity monitoring
C=manage user
D=resources
4=In which of the following tab of Domain in Administration console you can view or modify the user permission?
A=Permission
B=user activity monitoring
C=manage user
D=resources
ANS:A
5=the integration services holds two different values for a workflow variable what are they?
A=start value and end value
B=current value and end value
C=start value and current value
D=none
A=start value and end value
B=current value and end value
C=start value and current value
D=none
ANS:C
6=what are the available windows in workflow manager?
A= navigator, workspace, overview
B=workspace, output
C=navigator, workspace, output, overview
D=navigator, workspace, output
ANS:C
7=which of the following components integration service does not use to move data from source to target?
A=data transformation manager(DTM)process
B=service manager
C=load balancer
D= integration service process
ANS:C
8=we can run session task ………….?
8=we can run session task ………….?
A=concurrently
B=both concurrently & sequentially
C=sequentially
D=one sessin at a time
B=both concurrently & sequentially
C=sequentially
D=one sessin at a time
ANS:B
9=which of the below statement is not true about reusable transformation?
9=which of the below statement is not true about reusable transformation?
A=when you add a reusable transformation to a mapping you add an actual transformation
B=you can create reusable transformation in transformation developer or mapping developer
C=reusable transformation can be used in multiple mappings
D=the transformation marked as reusable in mapping designer cannot be reversed
ANS:A
10=how can you identify source bottleneck in case of relational source?
A=use a filter transformation
B=all of the listed options
C=use a read test mapping
D=use a database query
ANS:B
11=where can you create workflow task?
A=in task developer
B=in task developer or workflow designer
C= in task developer or workflow designer, or the worklet designer
D= in task developer or workflow designer, or the worklet designer or session wizard
ANS:B
12=what power center does while validating an expression which contain an user defined function?
A=a power center does not validate the user-defined function it just validate expression
B=a power center validates fails with validation error as it contain UDF
C=none
D=power center validates both the user-defined function and expression
B=a power center validates fails with validation error as it contain UDF
C=none
D=power center validates both the user-defined function and expression
ANS:A (NOT SURE)
13=you can configure expression syntax for a user-defined function by using the argument, as well as custom function TRUE/FALSE
14=parameter file contain which of the following parameter and variables?
1=service processvariable
2=workflow variable
3=worklet variable
4=workflow parameter
A=1,2 &4
B=1,2,3 & 4
C=1,2 & 3
D=1,2 &4
ANS:C
15=which of the following objects are required to create grid?
13=you can configure expression syntax for a user-defined function by using the argument, as well as custom function TRUE/FALSE
14=parameter file contain which of the following parameter and variables?
1=service processvariable
2=workflow variable
3=worklet variable
4=workflow parameter
A=1,2 &4
B=1,2,3 & 4
C=1,2 & 3
D=1,2 &4
ANS:C
15=which of the following objects are required to create grid?
A=nodes, workflow & session
B=domains
C=nodes and domain
D=nodes
ANS:C
16=integration services rolls back transaction under which circumstances?
B=domains
C=nodes and domain
D=nodes
ANS:C
16=integration services rolls back transaction under which circumstances?
A=invalid transaction
B=open transaction
C=roll back or session failure
D= closed transaction
B=open transaction
C=roll back or session failure
D= closed transaction
ANS:C
The Integration Service rolls back transactions in the following circumstances:
Rollback evaluation. The transaction control expression returns a rollback value.
Open transaction. You choose to roll back at the end of file.
Roll back on error. You choose to roll back commit transactions if the Integration Service encounters a non-fatal error.
Roll back on failed commit. If any target connection group in a transaction control unit fails to commit, the Integration Service rolls back all uncommitted data to the last successful commit point.
Rollback evaluation. The transaction control expression returns a rollback value.
Open transaction. You choose to roll back at the end of file.
Roll back on error. You choose to roll back commit transactions if the Integration Service encounters a non-fatal error.
Roll back on failed commit. If any target connection group in a transaction control unit fails to commit, the Integration Service rolls back all uncommitted data to the last successful commit point.
17=what can be done to improve integration services performation?
A=cache power center metadata for the repository services
B=use native drivers instead of ODBC drivers for the integration services
C=all of the listed options
D=run integration service with high availability
B=use native drivers instead of ODBC drivers for the integration services
C=all of the listed options
D=run integration service with high availability
ANS:C
18=which of the following target definition does power center 8 support?
18=which of the following target definition does power center 8 support?
A=relational. Flat file
B= relational. Flat file, XML files
C=relational only
D= relational. Flat file, XML files, COBOL files
ANS:B
19=which of the following setting you can configure while configuring the load balancing for a node?
19=which of the following setting you can configure while configuring the load balancing for a node?
A=resource
B=service level
C=dispatch mode
D=you cannot configure load balancing for node
ANS:C
20=which of the following transformation can be placed b/w the sort origin and the joiner transformation?
B=service level
C=dispatch mode
D=you cannot configure load balancing for node
ANS:C
20=which of the following transformation can be placed b/w the sort origin and the joiner transformation?
A=rank
B=filter
C=union
D=normalize
ANS:D
21=folder and session name are case sensitive ,mapping parameter and variable name are not case sensitive in parameter file TRUE/FALSE?
21=folder and session name are case sensitive ,mapping parameter and variable name are not case sensitive in parameter file TRUE/FALSE?
Session parameter names are not case sensitive.
Mapping parameter and variable names are not case sensitive TRUE.
22=What are the different states of debugger?
Mapping parameter and variable names are not case sensitive TRUE.
22=What are the different states of debugger?
A=initializing running and paused
B=running, paused & aborted
C=starting, running & stopped
D=running, aborted & stopped
23=what happen when you use $target in a stored procedure transformation and the pipeline contain multiple relational target?
B=running, paused & aborted
C=starting, running & stopped
D=running, aborted & stopped
23=what happen when you use $target in a stored procedure transformation and the pipeline contain multiple relational target?
A=none of the listed option
B=the DB server uses the database connections you specify for the target
C=the informatica server uses the database connection you specify the target
D= the session fails
ANS:D
24=how many output group can you create in a java transformation?
A=equal to no of output ports
B=not limited
C=equal to no of input ports
D=1
ANS:D
25=what type of cache he give performance benefit in Lookup?
25=what type of cache he give performance benefit in Lookup?
A=dynamic
B=shared & persistence
C=cache dosent give performance benefit
D=static
B=shared & persistence
C=cache dosent give performance benefit
D=static
ANS:B
26=which of the following is true about enabling a high precision data handling?
1=use the decimal datatype with a precision of 16 to 28 in the mapping
2=select enable high precission in the session properties
3=power center will automatically process the high precession data no explicit setting are required
A =1 & 2
B=1
C=2
D=3
ANS:A
27=which of the following statement accurately describes the repository service?
27=which of the following statement accurately describes the repository service?
A=each repository service can manage multiple repositories
B=a repository service may be located on two or more domains
C=each repository service can manage only one repository
D=each node must be assigned at least one repository service
B=a repository service may be located on two or more domains
C=each repository service can manage only one repository
D=each node must be assigned at least one repository service
ANS:C
28=in which of the following tabs of administration console-you can manage users, monitor user activity & domain activity?
28=in which of the following tabs of administration console-you can manage users, monitor user activity & domain activity?
A=domain tab
B=you cannot manage user and monitor user activity in administration console
C=logs tab
D=administration tab
ANS:D NOT SURE
29=workflow schedule can be ……………………?
A=both reusable & non-reusable
B=nonreusable
C=global
D=reusable
ANS:A
30=under which of the following condition you can edit the ports of a target definition in the mapping designer?
A=you cannot change the ports of a target definition in mapping designer under any condition
B=always
C=if target definition is reusable
D=if mapping is saved in the repository
ANS:C
B=always
C=if target definition is reusable
D=if mapping is saved in the repository
ANS:C
31=in joiner transformation to get performation benefits unsorted master source should be ?
1=large
2=small
3=don’t depend on source size
4=master source should not be cached
2=small
3=don’t depend on source size
4=master source should not be cached
A=1
B=2
C=3
D=4
ANS:B
32=workflow manager concist of how many tools?
32=workflow manager concist of how many tools?
A=4
B=3
C=5
D=2
ANS:3
33=a user sets the “treat rows as ” session property as “update” what is the effect of making this selection?
33=a user sets the “treat rows as ” session property as “update” what is the effect of making this selection?
A=all records processed by the session will be treated as update statement on the target table provided that the primary key constraint exists on the corresponding target table definition
B=all records processed by the session will be treated as update statement on the target table
C=the session allowa us the sue of the update strategy transformation provide that one or more update strategy transformation are present in the mapping run by the session
D= the session allowa us the sue of the update strategy transformation provide that one or more update strategy transformation are present in the mapping run by the session & provided that the primary key constraint exists on the corresponding target table definition
ANS:A
34=when you import the COBOL source in the source analyser how does the designer interpret each occurs clause?
34=when you import the COBOL source in the source analyser how does the designer interpret each occurs clause?
A=it creates the different column for each occurs statement in the COLOB file
B=each occurs produce multiple output column for each column in the COBOL data set
C=each occurs produce multiple unique identifier in the mapping pipeline, which may correspond to multiple rows or columns in the COBOL data set
D=it has no effect
C=each occurs produce multiple unique identifier in the mapping pipeline, which may correspond to multiple rows or columns in the COBOL data set
D=it has no effect
ANS:A
35=what you can do to improve session performance?
35=what you can do to improve session performance?
A=reduce the number of log events generated by the integration service when it run the session
B=set tracing level to verbos data
C=do not set session tracing level to terse
D=all of the listed options
ANS:A
36=the sql always returns one row for each input row in which of the following modes?
A=script
B=query
C=output
D=input
ANS:A
37=where can you create a reusable task?
A=in task developer or workflow designer
B=in task developer
C= in task developer or workflow designer or the worklet designer
D= in task developer or workflow designer or the worklet designer or session wizard
ANS:A
38=which of the following statement about DTM is incorrect?
A=retrieve and validate session information from the repository
B=reads the parameter file and expandsworkflow variable
C= verifies connection object permission
D=runs post-sessions stored procedure SQL and shell commands
ANS:A
39=can an active java transformation be converted into passive?
A=need to remove active transformation logic from code first
B=no
C=yes
D=yes, but reverse is not true
B=no
C=yes
D=yes, but reverse is not true
ANS:B
40=what are the threads that will be created when you start a session for execution?
40=what are the threads that will be created when you start a session for execution?
A=reader thread and writer thread
B=writer thread and transformation thread
C= reader thread and transformation thread
D=reader, writer and transformation thread
ANS:D
41=what happen in a router transformation when the filter condition for more than one output groups evalutes to true?
A=the router will pass the output data from all the output group where the expression is true
B=the roiuter will generate a transformation error
C=the router will pass the data from first output group where the expression is true
D= the router will pass the data from first output group where the expression is true & where the output port is mapped to another transformation
B=the roiuter will generate a transformation error
C=the router will pass the data from first output group where the expression is true
D= the router will pass the data from first output group where the expression is true & where the output port is mapped to another transformation
ANS:A
42=which statement is not true about bulk loading?
A=buk loading improves the performance of a session that insert a target amount of data to target database
B= integration service invokes a database bulk utility and bypass the database log
C=we can enable recovery by bulk loading
D= we can enable recovery by bulk loading when you load to DB2, Sybase, oracle or Microsoft SQL Server
B= integration service invokes a database bulk utility and bypass the database log
C=we can enable recovery by bulk loading
D= we can enable recovery by bulk loading when you load to DB2, Sybase, oracle or Microsoft SQL Server
ANS:C & D
43=what system variable can be used within a workflow?
43=what system variable can be used within a workflow?
A=workflow start time
B=session start time & workflow start time
C=sys date & workflow start time
D=session start time & sys date
B=session start time & workflow start time
C=sys date & workflow start time
D=session start time & sys date
ANS:C
44=what happen when you use $source in a stored procedure transformation and the pipeline contain multiple relational sources joined by a joiner transformation?
44=what happen when you use $source in a stored procedure transformation and the pipeline contain multiple relational sources joined by a joiner transformation?
A=none
B=the session fails
C=integration service uses different database connections
D=DB server uses different database connection
ANS:B
45=which of the following is an optional JAVA transformation property?
45=which of the following is an optional JAVA transformation property?
A=is active
B= transformation scope
C=language
D=generate transactions
ANS:A
46=what are the different dispatch mode of load balancing?
46=what are the different dispatch mode of load balancing?
A=adaptive
B=all listed options
C=round robin
D=metric based
B=all listed options
C=round robin
D=metric based
ANS:B
47=what happen when transaction control expression evaluates to a value other then commit. Rollback or continue?
47=what happen when transaction control expression evaluates to a value other then commit. Rollback or continue?
A=the integration service fails the session
B= the integration service rollback the transaction
C= the integration service does not perform any transaction changes
D= the integration service commit the transaction
ANS:A
48=what happen if you edit reusable task instance in workflow designer?
48=what happen if you edit reusable task instance in workflow designer?
A=you cannot edit the task instance of a reusable task in workflow designer
B=task cannot be reusable, you can only create it inside workflow
C= the original task definition changes
D=the task definition remain unchanged in task developer
ANS:D
49=when 3 session are running in a parallel in a workflow and suspension is enabled what will be the status of the workflow when one of the task fails and other two are still running?
49=when 3 session are running in a parallel in a workflow and suspension is enabled what will be the status of the workflow when one of the task fails and other two are still running?
A=suspending
B=running
C=failed
D=suspend
ANS:A
50=under what circumstances is it desirable to alter the datatype in the source qualifier?
50=under what circumstances is it desirable to alter the datatype in the source qualifier?
A=to alter the way the source definition binds data when it is importing into the mapping
B=when the precession required by the mapping is less then the precesion of the data stored in the table of flat file being read by the source qualifier
C=when the precision required by the mapping is greater than the
D=never. The data type in the source qualifier and the corresponding sources must match
ANS:D
51=aggregator function that cannot be used in incremental aggregator?
51=aggregator function that cannot be used in incremental aggregator?
1=percentage
2=standard deviation
3=variance
4=count
A=2 4 & 1
B=1 2 & 3
C=2 4 & 3
D=1 2 & 4
B=1 2 & 3
C=2 4 & 3
D=1 2 & 4
NOT CLEAR
52=by which of the following you access the data in informatica using the ODBC data source?
A=none
B=excel
C=excel & Sybase
D=flat files
ANS:C
53=you might use stored procedures to complete which of the following task?
53=you might use stored procedures to complete which of the following task?
A=determine if enough space exist in database
B=drop and recreate indexes
C=all of the listed options
D=check the status of the target database
ANS:C
54=which of the following types of objects are visible in repository manager navigation window?
54=which of the following types of objects are visible in repository manager navigation window?
A=mapping, repository user,source & target definition
B=repository, source, target, mapping
C=repository service, integration service, domain, folder
D=source & target definition, integration service, nodes
ANS:B
55=what value of new lookup row specifies that integration service updates the row in the cache?
A=0
B=1
C=2
D=3
ANS:2
56=which of the following are true about recovering the workflow?
A=when you recover the workflow, integration service recover the entire workflow and continue running the workflow path
B= when you recover the workflow, integration service recover the failed session and restart the workflow path
C= when you recover the workflow, integration service recover the failed session and continue running the rest of the task in the workflow path
D= you cannot recover a workflow if it fails you need to abort it and restart
B= when you recover the workflow, integration service recover the failed session and restart the workflow path
C= when you recover the workflow, integration service recover the failed session and continue running the rest of the task in the workflow path
D= you cannot recover a workflow if it fails you need to abort it and restart
ANS:B
57=in which of the following operating modes an integration service can run?
57=in which of the following operating modes an integration service can run?
A=normal & safe
B=normal & exclusive
C=enabled & disabled
D=enabled, disabled & exclusive
ANS:A
58=what will be the relationship b/w the code page and the informatica server, source & target?
A=source & target code pages must be subsets of informatica server
B=informatica server and source code page must be subsets of targets
C=informatica server & target code pages must be subsets of source
D=none
ANS:A
59=metadata is stored in……………………….?
A=DB
B=flat file
C=repository
D=ODBC
ANS:A
60=following filter condition used in filter
IIF(ISNULL(FIRST_NAME), TRUE,FALSE)
All the rows having NULL as FIRST_NAME…………………………………..
A=this will give error at run time and the record will be logged in the session log file
B= will bw discarded
C=the condition is invalid
D=will be passed to the next transformation
ANS:D
MySQL Interview Questions And Answers
MySQL Interview Questions And Answers
How do you start and stop MySQL on Windows? – net start MySQL, net stop MySQL
How do you start MySQL on Linux? – /etc/init.d/mysql start
Explain the difference between mysql and mysqli interfaces in PHP? – mysqli is the object-oriented version of mysql library functions.
What’s the default port for MySQL Server? – 3306
What does tee command do in MySQL? – tee followed by a filename turns on MySQL logging to a specified file. It can be stopped by command notee.
Can you save your connection settings to a conf file? – Yes, and name it ~/.my.conf. You might want to change the permissions on the file to 600, so that it’s not readable by others.
How do you change a password for an existing user via mysqladmin? – mysqladmin -u root -p password “newpassword”
Use mysqldump to create a copy of the database? – mysqldump -h mysqlhost -u username -p mydatabasename > dbdump.sql
Have you ever used MySQL Administrator and MySQL Query Browser? Describe the tasks you accomplished with these tools.
What are some good ideas regarding user security in MySQL? – There is no user without a password. There is no user without a user name. There is no user whose Host column contains % (which here indicates that the user can log in from anywhere in the network or the Internet). There are as few users as possible (in the ideal case only root) who have unrestricted access.
Explain the difference between MyISAM Static and MyISAM Dynamic. – In MyISAM static all the fields have fixed width. The Dynamic MyISAM table would include fields such as TEXT, BLOB, etc. to accommodate the data types with various lengths. MyISAM Static would be easier to restore in case of corruption, since even though you might lose some data, you know exactly where to look for the beginning of the next record.
What does myisamchk do? – It compressed the MyISAM tables, which reduces their disk usage.
Explain advantages of InnoDB over MyISAM? – Row-level locking, transactions, foreign key constraints and crash recovery.
Explain advantages of MyISAM over InnoDB? – Much more conservative approach to disk space management – each MyISAM table is stored in a separate file, which could be compressed then with myisamchk if needed. With InnoDB the tables are stored in tablespace, and not much further optimization is possible. All data except for TEXT and BLOB can occupy 8,000 bytes at most. No full text indexing is available for InnoDB. TRhe COUNT(*)s execute slower than in MyISAM due to tablespace complexity.
What are HEAP tables in MySQL? – HEAP tables are in-memory. They are usually used for high-speed temporary storage. No TEXT or BLOB fields are allowed within HEAP tables. You can only use the comparison operators = and <=>. HEAP tables do not support AUTO_INCREMENT. Indexes must be NOT NULL.
How do you control the max size of a HEAP table? – MySQL config variable max_heap_table_size.
What are CSV tables? – Those are the special tables, data for which is saved into comma-separated values files. They cannot be indexed.
Explain federated tables. – Introduced in MySQL 5.0, federated tables allow access to the tables located on other databases on other servers.
What is SERIAL data type in MySQL? – BIGINT NOT NULL PRIMARY KEY AUTO_INCREMENT
What happens when the column is set to AUTO INCREMENT and you reach the maximum value for that table? – It stops incrementing. It does not overflow to 0 to prevent data losses, but further inserts are going to produce an error, since the key has been used already.
Explain the difference between BOOL, TINYINT and BIT. – Prior to MySQL 5.0.3: those are all synonyms. After MySQL 5.0.3: BIT data type can store 8 bytes of data and should be used for binary data.
Explain the difference between FLOAT, DOUBLE and REAL. – FLOATs store floating point numbers with 8 place accuracy and take up 4 bytes. DOUBLEs store floating point numbers with 16 place accuracy and take up 8 bytes. REAL is a synonym of FLOAT for now.
If you specify the data type as DECIMAL (5,2), what’s the range of values that can go in this table? – 999.99 to -99.99. Note that with the negative number the minus sign is considered one of the digits.
What happens if a table has one column defined as TIMESTAMP? – That field gets the current timestamp whenever the row gets altered.
But what if you really want to store the timestamp data, such as the publication date of the article? – Create two columns of type TIMESTAMP and use the second one for your real data.
Explain data type TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP – The column exhibits the same behavior as a single timestamp column in a table with no other timestamp columns.
What does TIMESTAMP ON UPDATE CURRENT_TIMESTAMP data type do? – On initialization places a zero in that column, on future updates puts the current value of the timestamp in.
Explain TIMESTAMP DEFAULT ‘2006:09:02 17:38:44′ ON UPDATE CURRENT_TIMESTAMP. – A default value is used on initialization, a current timestamp is inserted on update of the row.
If I created a column with data type VARCHAR(3), what would I expect to see in MySQL table? – CHAR(3), since MySQL automatically adjusted the data type.
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