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. Which 3 databases exist directly after cluster initialization?

choose 3 options

template1

postgres

sysaux

template0

2 / 20

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

obj#

oid#

oid

obj

3 / 20

3. Which fork contains the actual table data?

free space map

visiblilty map

table map

Main fork

4 / 20

4. What is the purpose of wal writer?

writes WAL entries to disk

flushes dirty pages to disk.

collects usage statistics for the instance.

executes checkpoints

5 / 20

5. What is the process first launched at server start?

postman

init

postgres

pginit

6 / 20

6. How many files or forks on disk will a 10Mb table with no index have?

7 / 20

7. Which fork is specific for unlogged tables?

free space map

Main fork

Initialization fork

visiblilty map

8 / 20

8. Which of below are predefined schemas?

choose 3

pg_schema

pg_temp

pg_toast

information_schema

9 / 20

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

pg_tabspace

pg_tablespace

pg_symlinks

pg_tblspc

10 / 20

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

BREAD

TOAST

BAKE

GROW

11 / 20

11. Users should not modify the template0 database

True

False

12 / 20

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

rollback segments (RBS)

online redo logs (ORL)

undo segments (UNDO)

write-ahead log (WAL)

13 / 20

13. Tablespaces can be used to segregate data based on performance needs?

False

True

14 / 20

14. What is a schema?

A memory area used to cache data from LRU chains

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

15 / 20

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

False

True

16 / 20

16. A single Postgres Instance can server only one database?

True

False

17 / 20

17. What is the purpose of autovacuum?

Removes stale data from tables and indexes

Performs a backup of WAL logs

Rebuilds indexes with b level greater than 2

Deletes old logs and traces on disk

18 / 20

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

used space map

free space map

vacuum space map

wal space map

19 / 20

19. TOAST tables reside in a seperate schema?

True

False

20 / 20

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

System Catalog

Sys Catalog

Sysasm Catalog

Sysaux Catalog

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 of the below are valid Isolations Levels?

choose 2

Serializable

Read Committed

Rollback Read

Random Scatter

2 / 10

2. What is the default Isolation Level?

Read Uncommitted

Read Committed

Serializable

Repeatable Read

3 / 10

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

False

True

4 / 10

4. 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 also queries this same data.

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.

5 / 10

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

Repeatable Read

Read Committed

Read Uncommitted

Serializable

6 / 10

6. 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 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 and commits the change.

7 / 10

7. 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.

Apply explicit locks

Use a single SQL operator

Replace procedural code with declarative one.

8 / 10

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

True

False

9 / 10

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

SAFE

SOC2

ACID

HIPPA

10 / 10

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

False

True

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 of the below represent transaction IDs used for row versioning?

xid

xmin

xmax

xtime

2 / 10

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

pageinspect

pageheadinfo

pagedetect

pagesize

3 / 10

3. Information about subtransactions is stored under?

PGDATA/pg_subtrans

PGDATA/pg_min

PGDATA/subtrans

PGDATA/pg_xid

4 / 10

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

True

False

5 / 10

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

pg_current_xmin_id()

pg_current_xact_id()

pg_current_id()

pg_current_commit_id()

6 / 10

6. indexes do not use row versioning?

False

True

7 / 10

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

False

True

8 / 10

8. Page free space can often become fragmented?

False

True

9 / 10

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

True

False

10 / 10

10. CLOG contains how many bits for each transaction?

Your score is

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