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. To be able to restore data consistency, Postgres maintains

online redo logs (ORL)

write-ahead log (WAL)

undo segments (UNDO)

rollback segments (RBS)

2 / 20

2. What is a schema?

A memory area used to cache data from LRU chains

This is the same as a user in Postgres

Namespace that store all objects of a database

The name used to refer to a super user account

3 / 20

3. What is the purpose of the template1 database?

No such database

a template for all the other databases

regular database that you can use at your discretion

database used for temporary tables

4 / 20

4. Which of below are predefined schemas?

choose 3

information_schema

pg_toast

pg_temp

pg_schema

5 / 20

5. What is the purpose of the template0 database?

Useful for creating development schemas

No such database

Useful for Postgres support Services to debug issues

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

6 / 20

6. What is the purpose of wal writer?

executes checkpoints

collects usage statistics for the instance.

flushes dirty pages to disk.

writes WAL entries to disk

7 / 20

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

Initialize

CreateCluster

CreatePGC

StartNewPG

8 / 20

8. Which fork is specific for unlogged tables?

visiblilty map

free space map

Main fork

Initialization fork

9 / 20

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

False

True

10 / 20

10. A Postgres cluster consists of 2 or more physical servers accessing one Postgres Instance?

False

True

11 / 20

11. What is the purpose of the postgres database?

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

a template for all the other database

No such database

regular database that you can use at your discretion

12 / 20

12. What is the name of the system catalog table for relations?

pg_system

pg_catalog

pg_tables

pg_class

13 / 20

13. System Catalog tables begin with which prefix?

dba_

pg_

sys_

cat_

14 / 20

14. Each Database has its own System Catalog?

True

False

15 / 20

15. What column in system catalogs servers as the Primary Key

obj#

obj

oid

oid#

16 / 20

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

True

False

17 / 20

17. Tablespaces are used to define physical data layout?

True

False

18 / 20

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

free space map

used space map

vacuum space map

wal space map

19 / 20

19. What is the point of the pg_global tablespace?

stores temporary tables that are common to the whole cluster

stores system catalog objects that are common to the whole cluster

stores user tables that are common to the whole cluster

stores WAL logs used for global replication

20 / 20

20. What is the name of the mechanism used to store a row bigger than a page size?

BAKE

TOAST

GROW

BREAD

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

True

False

2 / 10

2. Which parameters sets the database default isolation level?

default_transaction_isolation

active_transaction_isolation

transaction_isolation_level

default_isolation_level

3 / 10

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

True

False

4 / 10

4. A phantom read anomaly occurs when?

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

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.

5 / 10

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

Read Committed

Serializable

Read Uncommitted

Repeatable Read

6 / 10

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

True

False

7 / 10

7. What is the default Isolation Level?

Read Uncommitted

Repeatable Read

Serializable

Read Committed

8 / 10

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

Select more than 1 answer below:

Issues a rollback after the commit to satisfy repeatable read.

Use a single SQL operator

Apply explicit locks

Replace procedural code with declarative one.

9 / 10

9. 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 and modifies this row 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, another transaction modifies this row between these reads and commits the change.

10 / 10

10. Which of the below would best describe a dirty read?

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

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

reading data direct from memory using pg_dirt

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. a transaction containing a savepoint is will still be considered as only a single transaction?

False

True

2 / 10

2. at any one time Postgres can have several versions of a row?

False

True

3 / 10

3. What does an Item Pointer contain?

choose 3

tuple offset from the start of the page

tuple length

tuple status

tuple xid

4 / 10

4. Postgres table physical data files are always cross compatible across platforms?

True

False

5 / 10

5. If a transaction aborts, all page changes are reverted(rolled back) in place?

False

True

6 / 10

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

pg_current_xact_id()

pg_current_xmin_id()

pg_current_commit_id()

pg_current_id()

7 / 10

7. Which 2 of the below represent transaction IDs used for row versioning?

xmax

xtime

xmin

xid

8 / 10

8. index row headers like table row headers contain xmin and xmax fields?

False

True

9 / 10

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

pageinspect

pagesize

pagedetect

pageheadinfo

10 / 10

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

xmas

xid

xmax

xmin

Your score is

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