Postgres Quiz Archive

You have 200 seconds to answer 20 Random questions so think fast!

You will need to score 80% or over to pass!

Created by

Paul Sammy

PostgreSQL 14 Internals Chapter 1

A quiz to test the knowledge of those reading and learning from Postgres 14 Internals book by Egor Rogov, covering topics in Chapter 1.

1 / 20

What is the name of the 2 default tablespaces created after initialization?

choose 2

pg_default

pg_temp

pg_tablespace

pg_global

2 / 20

Which fork contains the actual table data?

free space map

Main fork

table map

visiblilty map

3 / 20

What is a schema?

This is the same as a user in Postgres

The name used to refer to a super user account

Namespace that store all objects of a database

A memory area used to cache data from LRU chains

4 / 20

Some System Catalog tables are common to all databases in the cluster?

False

True

5 / 20

A schema can belong to more than one database?

False

True

6 / 20

What is the purpose of the visibility map?

provides an audit trail for the database

shows a page to be vacuumed or frozen

shows referential relationships for tables

provides the data decryption key

7 / 20

To understand each other, a client and a server must use one and the same interfacing protocol?

False

True

8 / 20

Users should not modify the template0 database

True

False

9 / 20

What is the default standard size for a fork file?

1GB

5GB

1MB

5MB

10 / 20

Tablespaces are used to define physical data layout?

False

True

11 / 20

Postgres by default has built in connection pooling abilities?

False

True

12 / 20

System Catalog tables begin with which prefix?

pg_

sys_

cat_

dba_

13 / 20

Which of below are predefined schemas?

choose 2

postgres

public

system

pg_catalog

14 / 20

What is the purpose of the postgres database?

a template for all the other database

regular database that you can use at your discretion

No such database

restoring data from a logical backup or creating a database with a different encoding

15 / 20

Which fork is specific for unlogged tables?

free space map

Main fork

Initialization fork

visiblilty map

16 / 20

How does Postgres know which schema to use if not specified?

Access Path

Schema Path

Directory Path

Search Path

17 / 20

TOAST tables reside in a seperate schema?

True

False

18 / 20

What is the purpose of the template0 database?

Useful for creating development schemas

No such database

Useful for restoring data from a logical backup or creating a database with a different encoding

Useful for Postgres support Services to debug issues

19 / 20

What is the purpose of wal writer?

flushes dirty pages to disk.

writes WAL entries to disk

collects usage statistics for the instance.

executes checkpoints

20 / 20

Each tablespaces can only be assigned for use by one database

False

True

Your score is

Created by

Paul Sammy

PostgreSQL 14 Internals Chapter 2

A quiz to test the knowledge of those reading and learning from Postgres 14 Internals book by Egor Rogov, covering topics in Chapter 2.

1 / 10

At any moment the database system can contain several versions of one and the same row?

True

False

2 / 10

Lost updates are forbidden by the standard at all isolation levels?

False

True

3 / 10

Which of the below would best describe a dirty read?

a session being able to see uncommited data altered by another session

reading data direct from memory using pg_dirt

a session being able to see commited data altered by another session

reading the data directly from file using a text editor such as vi or notepad

4 / 10

Which parameters sets the database default isolation level?

active_transaction_isolation

default_isolation_level

transaction_isolation_level

default_transaction_isolation

5 / 10

which of the below statements will start a transaction as Read Repeatable?

SET ISO=REPEATABLE_READ;

CREATE EXTENSTION REPEATABLE_READ;

ALTER SYSTEM SET ISO=REPEATABLE_READ;

BEGIN ISOLATION LEVEL REPEATABLE READ;

6 / 10

Based on Snapshot Isolation use of MVCC which of the below are permitted?

choose 3

Serializable

Read Committed

Repeatable Read

Read Uncommitted

7 / 10

Snapshot isolation is preferred but increases the number of required locks?

False

True

8 / 10

A phantom read anomaly occurs when?

The same transactions issues a commit, then a rollback to restore data to its original value

The same transaction executes two identical queries returning a set of rows that satisfy a particular condition, while another transaction adds some other rows satisfying this condition and commits.

The same transaction executes two identical queries returning a set of rows that satisfy a particular condition, while another transaction also queries this same data.

A transactions inserts a null value into a not null columns and commits

9 / 10

non-repeatable read anomaly occurs when?

A transaction reads one and the same row once, another transaction modifies this row between these reads and commits the change.

A transaction reads one and the same row twice, another transaction modifies this row between these reads issue a rollback.

A transaction reads one and the same row twice, another transaction modifies this row between these reads and commits the change.

A transaction reads one and the same row once and modifies this row and commits the change.

10 / 10

Which isolation level in theory could mean an application does not have to consider isolation anomalies?

Read Committed

Repeatable Read

Serializable

Read Uncommitted

Your score is

Created by

Paul Sammy

PostgreSQL 14 Internals Chapter 3

A quiz to test the knowledge of those reading and learning from Postgres 14 Internals book by Egor Rogov, covering topics in Chapter 3.

1 / 10

Which function can we use to find the current transaction ID?

pg_current_xmin_id()

pg_current_commit_id()

pg_current_xact_id()

pg_current_id()

2 / 10

A page along with its tuples is read into the buffer cache with compression transformations to enhance cache efficiency?

False

True

3 / 10

CLOG files are stored in which directory?

PGDATA/clog

PGDATA/pg_clog

PGDATA/pg_xact

PGDATA/pg_commit

4 / 10

Tuples can also be referred to as columns?

True

False

5 / 10

virtual IDs exist only in PGDATA/pg_vxid when not cached?

False

True

6 / 10

When a transaction is committed Postgres uses a special <replace with answer> structure?

commit log

transaction log

redo log

archive log

7 / 10

status of a subtransaction is written into CLOG?

False

True

8 / 10

psql provides a special mode that allows you to continue a transaction after a failure?

False

True

9 / 10

Page header sizes can be easily displayed using the <choose from answers> extension

pagedetect

pageheadinfo

pageinspect

pagesize

10 / 10

Rows of TOAST tables are handled in such a way that they are never update?

True

False

Your score is

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