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

What is the purpose of autovacuum?

Deletes old logs and traces on disk

Removes stale data from tables and indexes

Rebuilds indexes with b level greater than 2

Performs a backup of WAL logs

2 / 20

Users should not modify the template0 database

False

True

3 / 20

If we create a new tablespace which directory will symbolic links be created from?

pg_tblspc

pg_tablespace

pg_symlinks

pg_tabspace

4 / 20

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

5 / 20

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

6 / 20

What is the name of the directory that contains the files related to the Postgres cluster?

PGCORE

PGTIPS

PGDATA

PGBASE

7 / 20

What is the process first launched at server start?

pginit

postgres

init

postman

8 / 20

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

Sys Catalog

System Catalog

Sysasm Catalog

Sysaux Catalog

9 / 20

To be able to restore data consistency, Postgres maintains

write-ahead log (WAL)

rollback segments (RBS)

undo segments (UNDO)

online redo logs (ORL)

10 / 20

Files are logically split into pages?

False

True

11 / 20

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

pg_class

pg_tables

pg_system

pg_catalog

12 / 20

What is the purpose of the template0 database?

Useful for Postgres support Services to debug issues

No such database

Useful for creating development schemas

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

13 / 20

What 3 files/forks as a minimum make up a table on disk?

table map

free space map

visiblilty map

Main fork

14 / 20

Which fork is specific for unlogged tables?

visiblilty map

Initialization fork

free space map

Main fork

15 / 20

What is the purpose of the visibility map?

shows referential relationships for tables

shows a page to be vacuumed or frozen

provides an audit trail for the database

provides the data decryption key

16 / 20

Which fork contains the actual table data?

table map

visiblilty map

Main fork

free space map

17 / 20

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

choose 3

indexes

triggers

sequences

tables

18 / 20

What is the purpose of the template1 database?

regular database that you can use at your discretion

a template for all the other databases

No such database

database used for temporary tables

19 / 20

Postgres by default has built in connection pooling abilities?

False

True

20 / 20

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

choose 2

pg_temp

pg_tablespace

pg_global

pg_default

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

The SQL standard specifies three isolation levels?

False

True

2 / 10

Which of the below would best describe a dirty read?

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

reading data direct from memory using pg_dirt

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

3 / 10

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

Read Committed

Repeatable Read

Read Uncommitted

Serializable

4 / 10

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

False

True

5 / 10

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.

6 / 10

Which of the below are valid Isolations Levels?

choose 2

Random Scatter

Rollback Read

Serializable

Read Committed

7 / 10

A phantom read anomaly occurs when?

A transactions inserts a null value into a not null columns and commits

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.

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.

8 / 10

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.

9 / 10

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

choose 3

Repeatable Read

Read Uncommitted

Serializable

Read Committed

10 / 10

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

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

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

False

True

2 / 10

A page along with its tuples is read into the buffer cache with compression transformations to enhance cache efficiency?

False

True

3 / 10

What does an Item Pointer contain?

choose 3

tuple xid

tuple status

tuple offset from the start of the page

tuple length

4 / 10

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

False

True

5 / 10

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

Which 2 items does a Virtual XID consist of?

backend process ID

checksum

xmin

sequential number

7 / 10

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

True

False

8 / 10

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

COMMIT

CREATE

INSERT

DELETE

9 / 10

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

archive log

commit log

transaction log

redo log

10 / 10

The page header stores checksum and the sizes of the other parts of the page?

True

False

Your score is

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