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. What is the purpose of the visibility map?

provides an audit trail for the database

shows a page to be vacuumed or frozen

shows referential relationships for tables

provides the data decryption key

3 / 20

3. 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

4 / 20

4. Which fork is specific for unlogged tables?

visiblilty map

Main fork

free space map

Initialization fork

5 / 20

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

False

True

6 / 20

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

CreateCluster

Initialize

CreatePGC

StartNewPG

7 / 20

7. Tablespaces are used to define physical data layout?

False

True

8 / 20

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

obj#

obj

oid

oid#

9 / 20

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

choose 3

tables

sequences

indexes

triggers

10 / 20

10. What is the purpose of the template0 database?

Useful for Postgres support Services to debug issues

No such database

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

Useful for creating development schemas

11 / 20

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

True

False

12 / 20

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

True

False

13 / 20

13. What is the purpose of autovacuum?

Deletes old logs and traces on disk

Performs a backup of WAL logs

Rebuilds indexes with b level greater than 2

Removes stale data from tables and indexes

14 / 20

14. What is the purpose of the public schema?

no such schema

restricted schema for postgres internal usage only

schema used for heterogeneous replication

default schema for user objects

15 / 20

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

True

False

16 / 20

16. 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

17 / 20

17. Each Database has its own System Catalog?

False

True

18 / 20

18. Which 3 databases exist directly after cluster initialization?

choose 3 options

template1

sysaux

template0

postgres

19 / 20

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

True

False

20 / 20

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

pg_tables

pg_system

pg_catalog

pg_class

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?

True

False

2 / 10

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

True

False

3 / 10

3. A phantom read anomaly occurs when?

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 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.

4 / 10

4. 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

5 / 10

5. 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.

6 / 10

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

False

True

7 / 10

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

False

True

8 / 10

8. The SQL standard specifies three isolation levels?

False

True

9 / 10

9. What is the default Isolation Level?

Serializable

Repeatable Read

Read Uncommitted

Read Committed

10 / 10

10. 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

reading data direct from memory using pg_dirt

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

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. What does an Item Pointer contain?

choose 3

tuple offset from the start of the page

tuple length

tuple xid

tuple status

2 / 10

2. Page free space can often become fragmented?

False

True

3 / 10

3. CLOG contains how many bits for each transaction?

4 / 10

4. Tuples can also be referred to as columns?

True

False

5 / 10

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

CREATE

INSERT

COMMIT

DELETE

6 / 10

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

True

False

7 / 10

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

False

True

8 / 10

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

False

True

9 / 10

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

True

False

10 / 10

10. When a transaction is committed Postgres uses a special <replace with answer> structure?

archive log

redo log

transaction log

commit log

Your score is

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