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

1. What is the purpose of the template1 database?

a template for all the other databases

database used for temporary tables

regular database that you can use at your discretion

No such database

2 / 20

2. To be able to restore data consistency, Postgres maintains

undo segments (UNDO)

online redo logs (ORL)

write-ahead log (WAL)

rollback segments (RBS)

3 / 20

3. What command is used to create the Postgres cluster?

CreatePGC

StartNewPG

CreateCluster

Initialize

4 / 20

4. Which of below are predefined schemas?

choose 3

pg_temp

pg_toast

information_schema

pg_schema

5 / 20

5. What is the name of the directory that contains the files related to the Postgres cluster?

PGDATA

PGTIPS

PGBASE

PGCORE

6 / 20

6. What is the purpose of the visibility map?

shows a page to be vacuumed or frozen

shows referential relationships for tables

provides an audit trail for the database

provides the data decryption key

7 / 20

7. What is the name of the catalog that stores metadata for all cluster objects?

Sysasm Catalog

System Catalog

Sysaux Catalog

Sys Catalog

8 / 20

8. System Catalog tables begin with which prefix?

cat_

sys_

pg_

dba_

9 / 20

9. Each tablespaces can only be assigned for use by one database

True

False

10 / 20

10. What is a schema?

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

This is the same as a user in Postgres

11 / 20

11. Which fork is specific for unlogged tables?

Initialization fork

free space map

visiblilty map

Main fork

12 / 20

12. The pg_default tablespace should never be used to create user tables?

False

True

13 / 20

13. What is the purpose of wal writer?

writes WAL entries to disk

executes checkpoints

collects usage statistics for the instance.

flushes dirty pages to disk.

14 / 20

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

Directory Path

Schema Path

Access Path

Search Path

15 / 20

15. A schema can belong to more than one database?

True

False

16 / 20

16. Which fork keeps track of available space within pages?

used space map

wal space map

free space map

vacuum space map

17 / 20

17. The default Page size is 2k?

False

True

18 / 20

18. Postgres server spawns a new backend session for each connection?

True

False

19 / 20

19. Tablespaces are used to define physical data layout?

True

False

20 / 20

20. The information_schema schema provides information on Postgres release notes?

True

False

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

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

False

True

2 / 10

2. The more locks a transaction acquires, the better it is isolated from other transactions?

True

False

3 / 10

3. What is the acronym used for the attributes that ensure Data consistency, integrity and durability?

SAFE

ACID

HIPPA

SOC2

4 / 10

4. What are some of database features we can use to avoid a non repeatable read?

Select more than 1 answer below:

Apply explicit locks

Issues a rollback after the commit to satisfy repeatable read.

Use a single SQL operator

Replace procedural code with declarative one.

5 / 10

5. Data Consistency is best handled at the application layer rather than at the database layer?

True

False

6 / 10

6. Which of the below are valid Isolations Levels?

choose 2

Read Committed

Rollback Read

Serializable

Random Scatter

7 / 10

7. What is the default Isolation Level?

Serializable

Repeatable Read

Read Uncommitted

Read Committed

8 / 10

8. The SQL standard specifies three isolation levels?

False

True

9 / 10

9. A phantom read anomaly occurs when?

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

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

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.

10 / 10

10. non-repeatable read anomaly occurs when?

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, 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 once and modifies this row and commits the change.

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

1. Which 2 items does a Virtual XID consist of?

backend process ID

sequential number

checksum

xmin

2 / 10

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

pg_current_xmin_id()

pg_current_id()

pg_current_commit_id()

pg_current_xact_id()

3 / 10

3. When a row is created, its xmin value is set to the transaction ID of which command?

CREATE

DELETE

COMMIT

INSERT

4 / 10

4. CLOG Pages are never cached in memory?

False

True

5 / 10

5. In Postgres, tables are often referred to as which of the below?

clog

heap

view

dump

6 / 10

6. The page Special Space is located at the start of the page with highest address

True

False

7 / 10

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

False

True

8 / 10

8. status of a subtransaction is written into CLOG?

False

True

9 / 10

9. To identify different versions of one and the same row, PostgreSQL marks each of them with which two value?

xmax

xmas

xmin

xid

10 / 10

10. Which of the below are true about a Pages Item Pointer?

Each pointer uses 8 bytes

Also know as the pages table of contents

stored in PGDATA/itemptr directory

Each pointer uses 4 bytes

Your score is

Cookie	Duration	Description
cookielawinfo-checkbox-analytics	11 months	This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Analytics".
cookielawinfo-checkbox-functional	11 months	The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional".
cookielawinfo-checkbox-necessary	11 months	This cookie is set by GDPR Cookie Consent plugin. The cookies is used to store the user consent for the cookies in the category "Necessary".
cookielawinfo-checkbox-others	11 months	This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other.
cookielawinfo-checkbox-performance	11 months	This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Performance".
viewed_cookie_policy	11 months	The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. It does not store any personal data.