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 does Postgres know which schema to use if not specified?

Search Path

Directory Path

Schema Path

Access Path

2 / 20

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

write-ahead log (WAL)

rollback segments (RBS)

undo segments (UNDO)

online redo logs (ORL)

3 / 20

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

False

True

4 / 20

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

True

False

5 / 20

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

True

False

6 / 20

6. What is the purpose of wal writer?

writes WAL entries to disk

collects usage statistics for the instance.

flushes dirty pages to disk.

executes checkpoints

7 / 20

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

True

False

8 / 20

8. What is the purpose of the postgres database?

No such database

a template for all the other database

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

regular database that you can use at your discretion

9 / 20

9. Which 3 databases exist directly after cluster initialization?

choose 3 options

template1

postgres

template0

sysaux

10 / 20

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

11 / 20

11. System Catalog tables begin with which prefix?

cat_

dba_

sys_

pg_

12 / 20

12. Each Database has its own System Catalog?

False

True

13 / 20

13. Which fork is specific for unlogged tables?

free space map

Initialization fork

Main fork

visiblilty map

14 / 20

14. What is the purpose of the template0 database?

Useful for creating development schemas

No such database

Useful for Postgres support Services to debug issues

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

15 / 20

15. What is the purpose of the public schema?

no such schema

restricted schema for postgres internal usage only

default schema for user objects

schema used for heterogeneous replication

16 / 20

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

False

True

17 / 20

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

18 / 20

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

System Catalog

Sys Catalog

Sysasm Catalog

Sysaux Catalog

19 / 20

19. What is the purpose of the visibility map?

shows a page to be vacuumed or frozen

shows referential relationships for tables

provides an audit trail for the database

provides the data decryption key

20 / 20

20. Files are logically split into pages?

False

True

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. 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.

Apply explicit locks

Use a single SQL operator

2 / 10

2. 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 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.

3 / 10

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

choose 3

Serializable

Read Uncommitted

Read Committed

Repeatable Read

4 / 10

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

False

True

5 / 10

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

False

True

6 / 10

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

SOC2

SAFE

HIPPA

ACID

7 / 10

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

reading data direct from memory using pg_dirt

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

8 / 10

8. Which of the below are valid Isolations Levels?

choose 2

Rollback Read

Serializable

Random Scatter

Read Committed

9 / 10

9. What is the default Isolation Level?

Read Committed

Serializable

Repeatable Read

Read Uncommitted

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

True

False

2 / 10

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

False

True

3 / 10

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

xmin

xmax

xid

xtime

4 / 10

4. Information about subtransactions is stored under?

PGDATA/pg_subtrans

PGDATA/pg_min

PGDATA/pg_xid

PGDATA/subtrans

5 / 10

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

False

True

6 / 10

6. CLOG Pages are never cached in memory?

True

False

7 / 10

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

COMMIT

MERGE

DELETE

INSERT

8 / 10

8. Each page has a layer that usually consists of?

choose 2

flashback block

page header

free space

undo segment

9 / 10

9. Page free space can often become fragmented?

False

True

10 / 10

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

xmin

backend process ID

checksum

sequential number

Your score is

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