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

True

False

2 / 20

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

TOAST

BAKE

GROW

BREAD

3 / 20

3. Which of below are predefined schemas?

choose 3

pg_toast

information_schema

pg_schema

pg_temp

4 / 20

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

False

True

5 / 20

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

wal space map

used space map

free space map

vacuum space map

6 / 20

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

1MB

1GB

5MB

5GB

7 / 20

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

System Catalog

Sys Catalog

Sysasm Catalog

Sysaux Catalog

8 / 20

8. What is a schema?

The name used to refer to a super user account

Namespace that store all objects of a database

This is the same as a user in Postgres

A memory area used to cache data from LRU chains

9 / 20

9. Tablespaces are used to define physical data layout?

False

True

10 / 20

10. The default Page size is 2k?

True

False

11 / 20

11. What is the purpose of wal writer?

collects usage statistics for the instance.

flushes dirty pages to disk.

writes WAL entries to disk

executes checkpoints

12 / 20

12. Which 3 databases exist directly after cluster initialization?

choose 3 options

postgres

sysaux

template1

template0

13 / 20

13. Which fork contains the actual table data?

table map

visiblilty map

free space map

Main fork

14 / 20

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

False

True

15 / 20

15. TOAST tables reside in a seperate schema?

False

True

16 / 20

16. What is the name of the 2 default tablespaces created after initialization?

choose 2

pg_temp

pg_global

pg_tablespace

pg_default

17 / 20

17. System Catalog tables begin with which prefix?

dba_

pg_

sys_

cat_

18 / 20

18. How does Postgres know which schema to use if not specified?

Schema Path

Search Path

Access Path

Directory Path

19 / 20

19. What is the point of the pg_global tablespace?

stores system catalog objects that are common to the whole cluster

stores temporary tables that are common to the whole cluster

stores WAL logs used for global replication

stores user tables that are common to the whole cluster

20 / 20

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

pg_tables

pg_system

pg_class

pg_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 would best describe a dirty read?

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

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

2 / 10

2. 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.

3 / 10

3. non-repeatable read anomaly occurs when?

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.

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

4 / 10

4. 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

Replace procedural code with declarative one.

Apply explicit locks

Issues a rollback after the commit to satisfy repeatable read.

5 / 10

5. Which of the below are valid Isolations Levels?

choose 2

Rollback Read

Read Committed

Random Scatter

Serializable

6 / 10

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

choose 3

Repeatable Read

Read Committed

Serializable

Read Uncommitted

7 / 10

7. The SQL standard specifies three isolation levels?

False

True

8 / 10

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

Read Uncommitted

Serializable

Repeatable Read

Read Committed

9 / 10

9. What is the default Isolation Level?

Repeatable Read

Read Committed

Read Uncommitted

Serializable

10 / 10

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

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

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. CLOG files are stored in which directory?

PGDATA/pg_commit

PGDATA/clog

PGDATA/pg_xact

PGDATA/pg_clog

4 / 10

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

False

True

5 / 10

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

False

True

6 / 10

6. In Postgres, tables are often referred to as which of the below?

dump

view

clog

heap

7 / 10

7. indexes do not use row versioning?

True

False

8 / 10

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

xmin

sequential number

backend process ID

checksum

9 / 10

9. status of a subtransaction is written into CLOG?

False

True

10 / 10

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

True

False

Your score is

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