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. What is a schema?

This is the same as a user in Postgres

A memory area used to cache data from LRU chains

Namespace that store all objects of a database

The name used to refer to a super user account

2 / 20

2. Files are logically split into pages?

False

True

3 / 20

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

pg_system

pg_tables

pg_class

pg_catalog

4 / 20

4. Which fork contains the actual table data?

free space map

table map

Main fork

visiblilty map

5 / 20

5. What is the purpose of the template1 database?

a template for all the other databases

No such database

database used for temporary tables

regular database that you can use at your discretion

6 / 20

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

TOAST

GROW

BREAD

BAKE

7 / 20

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

oid#

obj#

obj

oid

8 / 20

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

True

False

9 / 20

9. What is the purpose of wal writer?

flushes dirty pages to disk.

writes WAL entries to disk

collects usage statistics for the instance.

executes checkpoints

10 / 20

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

True

False

11 / 20

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

True

False

12 / 20

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

False

True

13 / 20

13. Postgres uses a thread based process model?

False

True

14 / 20

14. Each Database has its own System Catalog?

False

True

15 / 20

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

True

False

16 / 20

16. What is the point of the pg_global tablespace?

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

stores temporary tables that are common to the whole cluster

17 / 20

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

1GB

5MB

1MB

5GB

18 / 20

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

False

True

19 / 20

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

20 / 20

20. What is the purpose of the template0 database?

No such database

Useful for Postgres support Services to debug issues

Useful for creating development schemas

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

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 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 commited data altered by another session

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

reading data direct from memory using pg_dirt

2 / 10

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

choose 3

Serializable

Repeatable Read

Read Uncommitted

Read Committed

3 / 10

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

BEGIN ISOLATION LEVEL REPEATABLE READ;

CREATE EXTENSTION REPEATABLE_READ;

ALTER SYSTEM SET ISO=REPEATABLE_READ;

SET ISO=REPEATABLE_READ;

4 / 10

4. The SQL standard specifies three isolation levels?

False

True

5 / 10

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

Select more than 1 answer below:

Use a single SQL operator

Issues a rollback after the commit to satisfy repeatable read.

Apply explicit locks

Replace procedural code with declarative one.

6 / 10

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

False

True

7 / 10

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

False

True

8 / 10

8. Which parameters sets the database default isolation level?

default_isolation_level

default_transaction_isolation

transaction_isolation_level

active_transaction_isolation

9 / 10

9. 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 adds some other rows satisfying this condition and commits.

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.

10 / 10

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

True

False

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

COMMIT

INSERT

DELETE

CREATE

2 / 10

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

False

True

3 / 10

3. Information about subtransactions is stored under?

PGDATA/subtrans

PGDATA/pg_xid

PGDATA/pg_min

PGDATA/pg_subtrans

4 / 10

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

False

True

5 / 10

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

xmin

xmas

xid

xmax

6 / 10

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

checksum

xmin

backend process ID

sequential number

7 / 10

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

True

False

8 / 10

8. UPDATE can be regarded as which 2 separate operations?

DELETE

MERGE

COMMIT

INSERT

9 / 10

9. The page Special Space is located at the start of the page with highest address

False

True

10 / 10

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

True

False

Your score is

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