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. How many rows in a page does Postgres aim to have before considering TOAST?

2 / 20

2. Which 3 databases exist directly after cluster initialization?

choose 3 options

postgres

template0

sysaux

template1

3 / 20

3. What is the purpose of the visibility map?

shows a page to be vacuumed or frozen

shows referential relationships for tables

provides the data decryption key

provides an audit trail for the database

4 / 20

4. What is the default standard size for a fork file?

5GB

5MB

1GB

1MB

5 / 20

5. What is the point of the pg_global tablespace?

stores WAL logs used for global replication

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

6 / 20

6. Which of below are predefined schemas?

choose 2

pg_catalog

postgres

public

system

7 / 20

7. Which of the below objects can be referred to as relations?

choose 3

sequences

tables

triggers

indexes

8 / 20

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

BREAD

TOAST

GROW

BAKE

9 / 20

9. If we create a new tablespace which directory will symbolic links be created from?

pg_tablespace

pg_symlinks

pg_tblspc

pg_tabspace

10 / 20

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

False

True

11 / 20

11. Users should not modify the template0 database

False

True

12 / 20

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

choose 2

pg_global

pg_tablespace

pg_default

pg_temp

13 / 20

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

PGCORE

PGDATA

PGTIPS

PGBASE

14 / 20

14. Which fork is specific for unlogged tables?

Initialization fork

visiblilty map

free space map

Main fork

15 / 20

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

False

True

16 / 20

16. Files are logically split into pages?

True

False

17 / 20

17. pg_catalog schema is used to store system catalog tables?

False

True

18 / 20

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

False

True

19 / 20

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

vacuum space map

free space map

used space map

wal space map

20 / 20

20. Which of below are predefined schemas?

choose 3

pg_temp

pg_schema

pg_toast

information_schema

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. Which parameters sets the database default isolation level?

default_transaction_isolation

active_transaction_isolation

default_isolation_level

transaction_isolation_level

2 / 10

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

False

True

3 / 10

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

Serializable

Repeatable Read

Read Committed

Read Uncommitted

4 / 10

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

True

False

5 / 10

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

False

True

6 / 10

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

True

False

7 / 10

7. 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.

8 / 10

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

False

True

9 / 10

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

BEGIN ISOLATION LEVEL REPEATABLE READ;

ALTER SYSTEM SET ISO=REPEATABLE_READ;

SET ISO=REPEATABLE_READ;

CREATE EXTENSTION REPEATABLE_READ;

10 / 10

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

Select more than 1 answer below:

Replace procedural code with declarative one.

Issues a rollback after the commit to satisfy repeatable read.

Use a single SQL operator

Apply explicit locks

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. CLOG Pages are never cached in memory?

True

False

2 / 10

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

True

False

3 / 10

3. Indexes values also support multi versioning with several versions of an index value existing at any point in time?

False

True

4 / 10

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

xmax

xtime

xmin

xid

5 / 10

5. 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

6 / 10

6. The page header is located in the highest address?

False

True

7 / 10

7. If a transaction is read only which kind of Transaction ID is it allocated?

magic XID

temporary XID

virtual XID

heap XID

8 / 10

8. CLOG files are stored in which directory?

PGDATA/pg_commit

PGDATA/pg_xact

PGDATA/pg_clog

PGDATA/clog

9 / 10

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

True

False

10 / 10

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

pageinspect

pagesize

pagedetect

pageheadinfo

Your score is

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