Elance PostgreSQL Test Answers
·
PostgreSQL can be used from just about any major programming language, including C, C++, Perl, Python, Java, Tcl, and PHP.
True
FALSE
A meta-command always begins with what?
Forwardslash character (/)
Dollar sign ($)
Backslash
character (\)
Question mark (?)
When you want to use a join between columns that are in the same table, you use what type of join?
union
right outer
left outer
self
True or False? VACUUM FULL shrinks indexes, optimizing database performance.
True
- This was addressed in version 9.0
False - This was addressed in version 9.0
True or False? When using a SELECT statement on a table, or group of tables, those resources are locked exclusively.
False
True
What do you call the application that makes requests of the PostgreSQL server?
Workstation
Client
Thin Client
Interface
Which of the following best describes a role:
A server's purpose within a cluster.
The purpose of a particular database.
A cluster's purpose.
A
template for authorization to various database objects.
The most common method to get data into a table is to use what command?
Insert
Write
Execute
Send
The basic psql command to list tables is?
\do
\dT
\h
\dt
In PostgreSQL, a named collection of tables is called what?
Trigger
View
Diagram
Schema
The heart of SQL is the __________ statement.
GROUP BY
INSERT INTO
SELECT
VALUES
PostgreSQL is
a
relational database management system.
a hierarchical database management system.
a network-type database management system.
an XML database management system.
PostgreSQL is:
An open-source SMTP server.
A NoSQL solution.
Enterprise-class proprietary software developed at Bell Labs, with a
basic set of features.
An
open-source ORDBMS developed at UC Berkley, which supports many modern
features.
When retrieving data in a particular table, we use the_____________ statement.
\dt
ORDER BY
SELECT
FROM
\i<filename>
We add data to PostgreSQL by using which statement?
INSERT
ADD
UPDATE
SELECT
PostgreSQL used what model of communication?
Client/Server
Network
Peer-to-Peer
Push Model
With PostgreSQL, you can access data by
Use function calls (APIs) to prepare and execute SQL statements, scan
result sets, and perform updates from a large variety of different programming
languages.
Use a command-line application to execute SQL statements
All
of these
Embed SQL directly into your application
PostgreSQL has many modern features including:
Complex SQL queries
SQL Sub-selects
All
of the above
Views
The SQL condition for pattern matching is?
IN
LIKE
DISTINCT
BETWEEN
What is the wrapper around the SQL command CREATE DATABASE?
newdb
add_DB
NEW_DB
createdb
PostgreSQL runs on:
all
major operating systems, including Linux, UNIX (AIX, BSD, HP-UX, SGI IRIX, Mac
OS X, Solaris, Tru64), and Windows.
on all UNIX versions except Solaris.
Linux and Windows only.
Windows only
What command tells PostgreSQL that all of the changes you made to a database should become permanent?
Apply
Execute
Commit
Send
PostgreSQL can be installed?
on a Windows computer via the PostgreSQL installer
from Linux binaries
All
of these
from the source code
____________ allow us to define formally in the database how different tables relate to each other.
Views
temporary tables
Foreign
Key Constraints
table management
Triggers can be configured to execute when which of the following operations are performed:
All
of the above
INSERT statements
UPDATE statements
DELETE statements
WAL stands for:
Write
Ahead Log
Write Ahead List
Write Anywhere List
Write Anywhere Logging
Deadlocks occur when:
Two users are connected to the same database at the same time.
Two
transactions hold exclusive locks on resources they both need.
Two users try to access the same table at the same time.
Data is being written to the same cell by separate processes at the same
time.
Tablespaces:
Allow
an administrator to designate specific locations in a file system where
database objects can be stored.
Are a fancy name for table.
Are the amount of disk space a table is using.
Are the width, or number of columns, of a particular table.
If you don’t specify ASC or DESC, PostgreSQL will assume you want to see results:
in
ascending order
grouped together by field type
in a random order
in descending order
True or false: With table inheritance, not null and check constraints are inherited.
False
True
True or False: A tablespace is the place where database objects are stored on disk.
False
True
True or False? ALTER TABLE may be issued while a VACUUM process is running.
False
True
True or False? PostgreSQL is so lightweight that performance and reliability are not affected by hardware.
False
True
A VACUUM operation is used:
To recover or reuse disk space occupied by updated or deleted rows.
To protect against loss of very old data due to transaction ID
wraparound.
To update data statistics used by the PostgreSQL query planner.
All
of these
True or False? Within a table, a single column may be encrypted.
True
False
The core PostgreSQL source code includes what interfaces?
Ruby and PHP interfaces
C++ and Java interfaces
The
C and embedded C interfaces
VB and VB.NET interfaces
Unless you specify NOT NULL, PostgreSQL will assume that a column is:
Required
Optional
Integers
Text
Query trees can be viewed in the server logs as long as which of the following configuration parameters are enabled?
debug_print_parse
debug_print_plan
All
of these
debug_print_rewritten
To describe a table in PostgreSQL which of the following is correct:
psql> \D table_name
psql> describe table_name
psql> DESCRIBE table_name
psql>
\d table_name
The value NULL, in database terminology, means?
All
of these
The value is undetermined at this time
The value is undetermined
The value is not relevant for this particular row.
To create a database in PostgreSQL, you must have the special CREATEDB privilege or
be an admin
have a script do it.
be
a superuser.
the special CREATETBL privilege
What does the following statement do? CREATE INDEX lower_title_idx ON books ((lower(title)));
Modifies an index in place to be lowercase
Creates a new index with a special operator class 'lower' for case
insensitive comparisons.
Creates
an index for efficient case-insensitive searches on the titles column within
the books table
Nothing, it's invalid SQL
Creates a non-write-locking index
What command allows you to edit PostgreSQL queries in your favorite editor ?
\ed
edit sql #go
\e
\edit
To prevent transaction wraparound, a VACUUM operation should be run on every table no less than once every:
2
billion transactions
5 billion transactions
4 billion transactions
3 billion transactions
The rule system:
Operates between the parser and the planner.
None of these
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.
All
of these
Asynchronous Commits:
None of these
All
of these
Allow transactions to complete more quickly
May cause recent transactions to be lost
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?
The server is idle, awaiting a client connection.
A transaction is possibly hung.
A user issued an IDLE statement to the database.
A
client is connected, and the server is awaiting input.
True or False? Only the administrator can make use of tablespaces.
True
False
This is used to determine how text is stored and sorted within PostgreSQL?
Collations
Index
Data Types
Database
Which statement is true about PostgreSQL data types?
A large object data type can be used to store data of unlimited size.
Only the INTEGER type can be declared as an array.
n'in CHARACTER(n) represents the number of bytes.
There
is a non-standard PostgreSQL data type, called Geometric data type, which
handles 2-dimensional data.
What command turns on timing?
\on timing
\start time
\time start
\timing
Advisory locks are allocated out of a shared memory pool whose size is defined by the configuration variables....
All
of these
None of these
max_connections
max_locks_per_transaction
To restore a PostgreSQL backup created with pg_dump, the following may be used:
$ psql -F database_dump.psql database_name
$ psql -R database_dump.psql database_name
$
psql -f database_dump.psql database_name
$ psql -r database_dump.psql database_name
In order to echo all input from script, you use the ________ psql command.
-a
-A
-l
-E
True or False? Dynamic Tracing is enabled by default at compile time.
False
True
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?
host partners bob 10.5.34.8/24 krb5
host partners bob 10.5.34.8/32 kerb5
host partners bob 10.5.34.8 kerb5
host
partners bob 10.5.34.8/32 krb5
What does MCV stand for?
Massive Checkpoint Vault
Most
Common Values
Most Common Variables
Many Common Variables
By default, in what subdirectory of the database data directory are WAL logs contained?
pg-xlog
pg-log
pg_log
pg_xlog
Which is NOT true of array indexes?
Partial functional indexes of arrays are supported on Btree, GiST, and
GIN indexes.
By
default PostgreSQL indexes arrays so that inner elements can be searched.
GIN indexes can search for arrays containing specific elements.
BTree indexes can search for array elements as long as the match begins
with the beginning of the array.
GiST indexes can be used to select arrays for specific values.
True or False? PostgreSQL supports Index Only Scans.
False
True
What is "index bloat"?
Index filling up with keys.
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.
Indexing inefficiently, like choosing to index timestamps in a table.
Indexing too many tables, resulting in inefficient database performance.
What are the join strategies available to the postgreSQL planner when a SELECT query contains two or more relations?
Nested
Loop Join, Merge Join, Hash Join
MERGE, JOIN
INNER JOIN, OUTER JOIN
MERGE, INNER JOIN, OUTER JOIN
To copy a database from server1 to server2, you might use which of the following:
pg_mv -h server1 database | pgsql -h server2 database
pg_dump -h server1 database > pgsql -h server2 database
pg_copy -h server1 database | psql -h server2 database
pg_dump
-h server1 database | psql -h server2 database
Which of the following is not a valid integer array?
'{}'
'{1,3,4,5,{6,7}}'
'{{1,2},{1,3},{1,4},{2,5}}'
'{1,3,4,5,6,7}'
'{{1,2,3,4,5,6}}'
What is the difference between DO 'some code...' and EXECUTE 'some code...' statements?
DO
lets you execute some plPgSql code without saving it to database and EXECUTE
lets you execute DDL or DML only
EXECUTE statement executes only prepared code, and DO can execute
without PREPARE statement
No difference - they both need a preparation for execution
DO prepares a statement and EXECUTE executes it
No difference - they both can execute a code without preparation
True or False? To increase server performance, automated CHECKPOINT operations should be setup in cron or Task Scheduler.
True
False
The syntax to view the indexes of an existing postgreSQL table is:
# index database_name.table_name
#
\d table_name
# \i table_name
# index table_name
Locks are recorded in:
pg_lock system logs
pg_locks
system view
pg_locks system logs
pg_lock system table
True or false? Hash indexes are not crash-safe
True
False
True or False? When restoring a database backed up with pg_dump, it's generally a good idea to enable WAL.
True
False
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.
False
True
Which statement is not true about a PostgreSQL domain?
A domain is created by 'CREATE DOMAIN'.
A domain can be used as a column type when defining a table.
Domain
is a namespace existing between databases and objects such as tables.
When defining a domain, you can add a default value and constraints to
the original data.
The extension used for data encryption/decryption within PostgreSQL is:
crypto
pgcrypt
pgcrypto
pgencrypt
Which of the following is NOT a feature of user defined functions?
They can be written in various different languages
Functions marked IMMUTABLE can have their output indexed
They can return multiple result sets via refcursors
They can perform most database management tasks
They
can initiate subtransactions
To create a database that supports UTF-8, the following command can be used:
createdb -E UTF-8 -O user database_name
createdb
-E UTF8 -O user database_name
createdb -C UTF8 database_name
createdb -C UTF8 -O user database_name
What is a TOAST file?
A list of clients not allowed to connect to the database.
A file storing data that was unable to be written to the database, and
will be expunged once the server shuts down.
A
file containing values too wide to fit comfortably in the main table
A file containining transactions which were unsuccessfully completed due
to errors.
True or False: PostgreSQL allows you to implement table inheritance. This should be defined with the special keyword INHERITIS in the table design.
False
True
WAL segment size is determined:
By
the configure script at compile time
By the wal_segment_size configuration parameter in postgresql.conf
By the administrator at runtime, or through the startup script.
It is statically set within the source code.
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.
relational
network
hierarchical
structured
When identifying rows uniquely, we use__________keys.
command
surrogate
standard
unique
True or false: With table inheritance child tables inherit primary and foreign key definitions from their parents
False
True
True or False? To enable continuous archiving, all you have to do is set archive_mode to 'on' in postgresql.conf
True
False
Subscribe to:
Posts (Atom)
