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 fork contains the actual table data?

table map

Main fork

visiblilty map

free space map

2 / 20

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

True

False

3 / 20

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

Sys Catalog

Sysaux Catalog

Sysasm Catalog

System Catalog

4 / 20

4. It is the postmasters job to listener for incoming connections?

False

True

5 / 20

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

False

True

6 / 20

6. Postgres uses a thread based process model?

False

True

7 / 20

7. TOAST tables reside in a seperate schema?

False

True

8 / 20

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

False

True

9 / 20

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

5MB

1MB

1GB

5GB

10 / 20

10. 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

11 / 20

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

12 / 20

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

pginit

init

postman

postgres

13 / 20

13. What is the purpose of wal writer?

executes checkpoints

writes WAL entries to disk

collects usage statistics for the instance.

flushes dirty pages to disk.

14 / 20

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

False

True

15 / 20

15. Which of below are predefined schemas?

choose 3

information_schema

pg_temp

pg_schema

pg_toast

16 / 20

16. What is the purpose of the template0 database?

Useful for creating development schemas

Useful for Postgres support Services to debug issues

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

No such database

17 / 20

17. What is the purpose of autovacuum?

Rebuilds indexes with b level greater than 2

Deletes old logs and traces on disk

Performs a backup of WAL logs

Removes stale data from tables and indexes

18 / 20

18. Each Database has its own System Catalog?

False

True

19 / 20

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

20 / 20

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

undo segments (UNDO)

online redo logs (ORL)

rollback segments (RBS)

write-ahead log (WAL)

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

True

False

2 / 10

2. 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 also queries this same data.

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.

3 / 10

3. What is the default Isolation Level?

Serializable

Read Committed

Read Uncommitted

Repeatable Read

4 / 10

4. 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.

5 / 10

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

SOC2

HIPPA

SAFE

ACID

6 / 10

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

True

False

7 / 10

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

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

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 data direct from memory using pg_dirt

8 / 10

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

False

True

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

10 / 10

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

choose 3

Read Committed

Read Uncommitted

Serializable

Repeatable Read

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

False

True

2 / 10

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

True

False

3 / 10

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

xmin

xmax

xtime

xid

4 / 10

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

False

True

5 / 10

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

True

False

6 / 10

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

Each pointer uses 4 bytes

Each pointer uses 8 bytes

stored in PGDATA/itemptr directory

Also know as the pages table of contents

7 / 10

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

False

True

8 / 10

8. Tuples can also be referred to as columns?

False

True

9 / 10

9. What does an Item Pointer contain?

choose 3

tuple xid

tuple offset from the start of the page

tuple length

tuple status

10 / 10

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

checksum

sequential number

xmin

backend process ID

Your score is

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