PostgreSQL MCQs
PostgreSQL MCQs
These PostgreSQL multiple-choice questions and their answers will help you strengthen your grip on the subject of PostgreSQL. You can prepare for an upcoming exam or job interview with these PostgreSQL MCQs.
So scroll down and start answering.
1: PostgreSQL can be used from just about any major programming language, including C, C++, Perl, Python, Java, Tcl, and PHP.
A. True
B. FALSE
2: The value NULL, in database terminology, means?
A. The value is not relevant for this particular row.
B. The value is undetermined
C. The value is undetermined at this time
D. All of these
3: True or false: With table inheritance, not null and check constraints are inherited.
A. False
B. True
4: What do you call the application that makes requests of the PostgreSQL server?
A. Workstation
B. Thin Client
C. Interface
D. Client
5: What is the wrapper around the SQL command CREATE DATABASE?
A. newdb
B. add_DB
C. NEW_DB
D. createdb
6: When retrieving data in a particular table, we use the_____________ statement.
A. SELECT FROM
B. \dt
C. \i<filename>
D. ORDER BY
7: PostgreSQL is:
A. An open-source ORDBMS developed at UC Berkley, which supports many modern features.
B. Enterprise-class proprietary software developed at Bell Labs, with a basic set of features.
C. A NoSQL solution.
D. An open-source SMTP server.
8: PostgreSQL is
A. an XML database management system.
B. a network-type database management system.
C. a hierarchical database management system.
D. a relational database management system.
9: PostgreSQL has many modern features including:
A. SQL Sub-selects
B. All of the above
C. Views
D. Complex SQL queries
10: PostgreSQL can be installed?
A. from the source code
B. from Linux binaries
C. on a Windows computer via the PostgreSQL installer
D. All of these
11: PostgreSQL runs on:
A. Windows only
B. all major operating systems, including Linux, UNIX (AIX, BSD, HP-UX, SGI IRIX, Mac OS X, Solaris, Tru64), and Windows.
C. on all UNIX versions except Solaris.
D. Linux and Windows only.
12: With PostgreSQL, you can access data by
A. Use function calls (APIs) to prepare and execute SQL statements, scan result sets, and perform updates from a large variety of different programming languages.
B. Embed SQL directly into your application
C. Use a command-line application to execute SQL statements
D. All of these
13: Triggers can be configured to execute when which of the following operations are performed:
A. All of the above
B. DELETE statements
C. INSERT statements
D. UPDATE statements
14: We add data to PostgreSQL by using which statement?
A. UPDATE
B. ADD
C. SELECT
D. INSERT
15: The heart of SQL is the __________ statement.
A. VALUES
B. INSERT INTO
C. SELECT
D. GROUP BY
16: The most common method to get data into a table is to use what command?
A. Write
B. Send
C. Execute
D. Insert
17: In PostgreSQL, a named collection of tables is called what?
A. Schema
B. View
C. Diagram
D. Trigger
18: What command tells PostgreSQL that all of the changes you made to a database should become permanent?
A. Commit
B. Send
C. Apply
D. Execute
19: The SQL condition for pattern matching is?
A. IN
B. DISTINCT
C. LIKE
D. BETWEEN
20: ____________ allow us to define formally in the database how different tables relate to each other.
A. table management
B. Views
C. temporary tables
D. Foreign Key Constraints
21: Which of the following best describes a role:
A. The purpose of a particular database.
B. A cluster's purpose.
C. A server's purpose within a cluster.
D. A template for authorization to various database objects.
22: The basic psql command to list tables is?
A. \do
B. \h
C. \dT
D. \dt
23: True or False? VACUUM FULL shrinks indexes, optimizing database performance.
A. True - This was addressed in version 9.0
B. False - This was addressed in version 9.0
24: WAL stands for:
A. Write Anywhere List
B. Write Anywhere Logging
C. Write Ahead Log
D. Write Ahead List
25: Deadlocks occur when:
A. Two users try to access the same table at the same time.
B. Two users are connected to the same database at the same time.
C. Data is being written to the same cell by separate processes at the same time.
D. Two transactions hold exclusive locks on resources they both need.
26: True or False? When using a SELECT statement on a table, or group of tables, those resources are locked exclusively.
A. False
B. True
27: Tablespaces:
A. Allow an administrator to designate specific locations in a file system where database objects can be stored.
B. Are a fancy name for table.
C. Are the width, or number of columns, of a particular table.
D. Are the amount of disk space a table is using.
28: If you don’t specify ASC or DESC, PostgreSQL will assume you want to see results:
A. in ascending order
B. in a random order
C. grouped together by field type
D. in descending order
29: True or False: A tablespace is the place where database objects are stored on disk.
A. True
B. False
30: When you want to use a join between columns that are in the same table, you use what type of join?
A. right outer
B. left outer
C. union
D. self
31: True or False? Within a table, a single column may be encrypted.
A. False
B. True
32: True or False? ALTER TABLE may be issued while a VACUUM process is running.
A. False
B. True
33: The core PostgreSQL source code includes what interfaces?
A. VB and VB.NET interfaces
B. The C and embedded C interfaces
C. Ruby and PHP interfaces
D. C++ and Java interfaces
34: A VACUUM operation is used:
A. All of these
B. To recover or reuse disk space occupied by updated or deleted rows.
C. To update data statistics used by the PostgreSQL query planner.
D. To protect against loss of very old data due to transaction ID wraparound.
35: True or False? PostgreSQL is so lightweight that performance and reliability are not affected by hardware.
A. False
B. True
36: Unless you specify NOT NULL, PostgreSQL will assume that a column is:
A. Optional
B. Text
C. Required
D. Integers
37: To describe a table in PostgreSQL which of the following is correct:
A. psql> describe table_name
B. psql> \D table_name
C. psql> DESCRIBE table_name
D. psql> \d table_name
38: Query trees can be viewed in the server logs as long as which of the following configuration parameters are enabled?
A. debug_print_parse
B. All of these
C. debug_print_rewritten
D. debug_print_plan
39: A meta-command always begins with what?
A. Backslash character (\)
B. Dollar sign ($)
C. Question mark (?)
D. Forwardslash character (/)
40: To create a database in PostgreSQL, you must have the special CREATEDB privilege or
A. the special CREATETBL privilege
B. have a script do it.
C. be a superuser.
D. be an admin
41: What does the following statement do? CREATE INDEX lower_title_idx ON books ((lower(title)));
A. Nothing, it's invalid SQL
B. Creates a non-write-locking index
C. Modifies an index in place to be lowercase
D. Creates a new index with a special operator class 'lower' for case insensitive comparisons.
E. Creates an index for efficient case-insensitive searches on the titles column within the books table
42: What command allows you to edit PostgreSQL queries in your favorite editor ?
A. \ed
B. edit sql #go
C. \edit
D. \e
43: To prevent transaction wraparound, a VACUUM operation should be run on every table no less than once every:
A. 4 billion transactions
B. 3 billion transactions
C. 2 billion transactions
D. 5 billion transactions
44: Asynchronous Commits:
A. May cause recent transactions to be lost
B. None of these
C. All of these
D. Allow transactions to complete more quickly
45: The rule system:
A. Takes the output of the parser, one query tree, and the user-defined rewrite rules, which are also query trees with some extra information, and creates zero or more query trees as result.
B. Operates between the parser and the planner.
C. None of these
D. All of these
46: True or False? Only the administrator can make use of tablespaces.
A. False
B. True
47: What command turns on timing?
A. \start time
B. \timing
C. \on timing
D. \time start
48: When looking at 'ps' output on a unix system, you see the following: postgres 1016 0.1 2.4 6532 3080 pts/1 SN 13:19 0:00 postgres: tgl regression [local] idle in transaction What does "idle in transaction" mean?
A. A client is connected, and the server is awaiting input.
B. The server is idle, awaiting a client connection.
C. A transaction is possibly hung.
D. A user issued an IDLE statement to the database.
49: Advisory locks are allocated out of a shared memory pool whose size is defined by the configuration variables....
A. max_connections
B. None of these
C. max_locks_per_transaction
D. All of these
50: This is used to determine how text is stored and sorted within PostgreSQL?
A. Collations
B. Index
C. Data Types
D. Database
51: True or False? Dynamic Tracing is enabled by default at compile time.
A. True
B. False
52: Which statement is true about PostgreSQL data types?
A. n'in CHARACTER(n) represents the number of bytes.
B. A large object data type can be used to store data of unlimited size.
C. There is a non-standard PostgreSQL data type, called Geometric data type, which handles 2-dimensional data.
D. Only the INTEGER type can be declared as an array.
53: True or False? PostgreSQL supports Index Only Scans.
A. False
B. True
54: What does MCV stand for?
A. Massive Checkpoint Vault
B. Many Common Variables
C. Most Common Variables
D. Most Common Values
55: To restore a PostgreSQL backup created with pg_dump, the following may be used:
A. $ psql -F database_dump.psql database_name
B. $ psql -f database_dump.psql database_name
C. $ psql -R database_dump.psql database_name
D. $ psql -r database_dump.psql database_name
56: In order to echo all input from script, you use the ________ psql command.
A. -l
B. -A
C. -E
D. -a
57: By default, in what subdirectory of the database data directory are WAL logs contained?
A. pg_log
B. pg-xlog
C. pg_xlog
D. pg-log
58: What is "index bloat"?
A. Indexing too many tables, resulting in inefficient database performance.
B. No-longer-needed keys in an index aren't reclaimed, therefore increasing space required to store an index, as well as time it takes to scan.
C. Indexing inefficiently, like choosing to index timestamps in a table.
D. Index filling up with keys.
59: Which is NOT true of array indexes?
A. Partial functional indexes of arrays are supported on Btree, GiST, and GIN indexes.
B. GiST indexes can be used to select arrays for specific values.
C. GIN indexes can search for arrays containing specific elements.
D. By default PostgreSQL indexes arrays so that inner elements can be searched.
E. BTree indexes can search for array elements as long as the match begins with the beginning of the array.
60: Bob works for StegaCorp. His workstation's IP address is 10.5.34.8. He needs access to a database called "partners" directly from his workstation. Which of the following is the correct entry in pg_hba.conf?
A. host partners bob 10.5.34.8/32 krb5
B. host partners bob 10.5.34.8 kerb5
C. host partners bob 10.5.34.8/24 krb5
D. host partners bob 10.5.34.8/32 kerb5
61: What are the join strategies available to the postgreSQL planner when a SELECT query contains two or more relations?
A. INNER JOIN, OUTER JOIN
B. MERGE, INNER JOIN, OUTER JOIN
C. MERGE, JOIN
D. Nested Loop Join, Merge Join, Hash Join
62: To copy a database from server1 to server2, you might use which of the following:
A. pg_mv -h server1 database | pgsql -h server2 database
B. pg_dump -h server1 database > pgsql -h server2 database
C. pg_dump -h server1 database | psql -h server2 database
D. pg_copy -h server1 database | psql -h server2 database
63: True or False? To increase server performance, automated CHECKPOINT operations should be setup in cron or Task Scheduler.
A. False
B. True
64: Which of the following is not a valid integer array?
A. '{1,3,4,5,6,7}'
B. '{{1,2},{1,3},{1,4},{2,5}}'
C. '{}'
D. '{1,3,4,5,{6,7}}'
E. '{{1,2,3,4,5,6}}'
A. DO prepares a statement and EXECUTE executes it
B. No difference - they both need a preparation for execution
C. No difference - they both can execute a code without preparation
D. EXECUTE statement executes only prepared code, and DO can execute without PREPARE statement
E. DO lets you execute some plPgSql code without saving it to database and EXECUTE lets you execute DDL or DML only
66: Locks are recorded in:
A. pg_lock system table
B. pg_locks system view
C. pg_lock system logs
D. pg_locks system logs
67: True or False? When restoring a database backed up with pg_dump, it's generally a good idea to enable WAL.
A. True
B. False
68: True or false? Hash indexes are not crash-safe
A. False
B. True
69: True or false: When a table is created which uses a table name as a column type, not null constraints on the column type's table definition are honored by the including table.
A. True
B. False
70: The syntax to view the indexes of an existing postgreSQL table is:
A. # index database_name.table_name
B. # \i table_name
C. # \d table_name
D. # index table_name
71: Which statement is not true about a PostgreSQL domain?
A. A domain can be used as a column type when defining a table.
B. When defining a domain, you can add a default value and constraints to the original data.
C. A domain is created by 'CREATE DOMAIN'.
D. Domain is a namespace existing between databases and objects such as tables.
72: The extension used for data encryption/decryption within PostgreSQL is:
A. pgcrypto
B. crypto
C. pgcrypt
D. pgencrypt
73: What is a TOAST file?
A. A file containining transactions which were unsuccessfully completed due to errors.
B. A list of clients not allowed to connect to the database.
C. A file containing values too wide to fit comfortably in the main table
D. A file storing data that was unable to be written to the database, and will be expunged once the server shuts down.
74: To create a database that supports UTF-8, the following command can be used:
A. createdb -E UTF-8 -O user database_name
B. createdb -C UTF8 database_name
C. createdb -C UTF8 -O user database_name
D. createdb -E UTF8 -O user database_name
75: True or False: PostgreSQL allows you to implement table inheritance. This should be defined with the special keyword INHERITIS in the table design.
A. False
B. True
76: Which of the following is NOT a feature of user defined functions?
A. Functions marked IMMUTABLE can have their output indexed
B. They can be written in various different languages
C. They can perform most database management tasks
D. They can return multiple result sets via refcursors
E. They can initiate subtransactions
77: WAL segment size is determined:
A. It is statically set within the source code.
B. By the administrator at runtime, or through the startup script.
C. By the wal_segment_size configuration parameter in postgresql.conf
D. By the configure script at compile time
78: The __________ database model has the advantage of being able to quickly discover all of the records of one type that are related to a specific record of another type by following the pointers from the starting record.
A. hierarchical
B. structured
C. relational
D. network
79: When identifying rows uniquely, we use__________keys.
A. command
B. standard
C. surrogate
D. unique
80: True or false: With table inheritance child tables inherit primary and foreign key definitions from their parents
A. False
B. True
81: True or False? To enable continuous archiving, all you have to do is set archive_mode to
A. True
B. False
A. Yes
B. No
A. create table foo (bar int array);
B. create table foo (bar integer[]);
C. create table foo (bar array int);
D. create table foo (bar[] int);
E. None of the above
A. True
B. False
A. A-tree
B. B-tree
C. GiST
D. Hash
E. GIN
F. None of the above
pg_dump -Fc dbname > filename
A. psql -f filename dbname
B. psql -Fc filename dbname
C. pg_restore filename dbname
D. pg_restore -d dbname filename
E. None of the above
A. File synchronization will be deactivated
B. fsync is not a valid configuration option
C. PostgreSQL will not enforce write ahead log flush
D. It will turn off fast synchronization
E. None of the above
A. Hash
B. A-tree
C. B-tree
D. GIN
E. GiST
A. Trust
B. PAM
C. LDAP
D. Radius
E. Password
A. You cannot
B. Leave a superuser connected all the time
C. Set superuser_reserved_connections in postgresql.conf
D. Kill postmaster and connect to it
E. None of the above
A. ts_highlight
B. ts_tag
C. ts_headline
D. ts_select
E. None of the above
Create table foo (bar varchar);
What will be the size limit of the bar?
A. 256
B. 1024
C. 1
D. No limit (It will be equivalent to the text)
E. None of the above
A. True
B. False
SELECT products[1] FROM store_products;
A. True
B. False
A. 5000
B. 541
C. 5432
D. 63
E. None of the above
A. Per-row triggers
B. Per-table triggers
C. Per-database triggers
D. Per-statement triggers
A. *
B. $
C. %
D. &
E. None of the above
A. 4 numeric values with up to 3 digits to the right of the decimal point.
B. A numeric value with up to 7 digits in total, 3 of which can be to the right of the decimal point.
C. A numeric value with up to 4 digits in total, 3 of which can be to the right of the decimal point.
D. A numeric value with at least 4 digits, 3 of which must be to the right of the decimal point.
A. By ID
B. By insertion date
C. By name
D. The ordering is unknown if not specified
E. None of the above
A. SELECT random() * FROM tab LIMIT 1;
B. SELECT * FROM tab ORDER BY random() LIMIT 1;
C. SELECT * FROM tab RANDOM LIMIT 1 ;
D. SELECT RANDOM 1 from tab;
E. None of the above
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