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

Which fork contains the actual table data?

Main fork

free space map

table map

visiblilty map

2 / 20

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

3 / 20

What is the purpose of autovacuum?

Removes stale data from tables and indexes

Deletes old logs and traces on disk

Rebuilds indexes with b level greater than 2

Performs a backup of WAL logs

4 / 20

pg_catalog schema is used to store system catalog tables?

True

False

5 / 20

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

choose 2

pg_temp

pg_global

pg_default

pg_tablespace

6 / 20

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

7 / 20

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

False

True

8 / 20

What is the purpose of the visibility map?

provides an audit trail for the database

provides the data decryption key

shows a page to be vacuumed or frozen

shows referential relationships for tables

9 / 20

What is a schema?

This is the same as a user in Postgres

A memory area used to cache data from LRU chains

The name used to refer to a super user account

Namespace that store all objects of a database

10 / 20

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

pg_tables

pg_class

pg_catalog

pg_system

11 / 20

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

Schema Path

Directory Path

Search Path

Access Path

12 / 20

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

Sysaux Catalog

Sys Catalog

System Catalog

Sysasm Catalog

13 / 20

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

Main fork

visiblilty map

table map

free space map

14 / 20

Each tablespaces can only be assigned for use by one database

False

True

15 / 20

A single Postgres Instance can server only one database?

True

False

16 / 20

What is the purpose of the template1 database?

No such database

regular database that you can use at your discretion

database used for temporary tables

a template for all the other databases

17 / 20

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

False

True

18 / 20

Which of below are predefined schemas?

choose 2

pg_catalog

public

system

postgres

19 / 20

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

pg_tblspc

pg_tablespace

pg_tabspace

pg_symlinks

20 / 20

The default Page size is 2k?

True

False

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

A phantom read anomaly occurs when?

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.

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.

2 / 10

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

False

True

3 / 10

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

False

True

4 / 10

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

choose 3

Serializable

Repeatable Read

Read Uncommitted

Read Committed

5 / 10

non-repeatable read anomaly occurs when?

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.

A transaction reads one and the same row twice, another transaction modifies this row between these reads issue a rollback.

6 / 10

Which parameters sets the database default isolation level?

active_transaction_isolation

default_isolation_level

transaction_isolation_level

default_transaction_isolation

7 / 10

The SQL standard specifies three isolation levels?

True

False

8 / 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

Apply explicit locks

Replace procedural code with declarative one.

Issues a rollback after the commit to satisfy repeatable read.

9 / 10

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

Serializable

Read Uncommitted

Read Committed

Repeatable Read

10 / 10

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

CREATE EXTENSTION REPEATABLE_READ;

SET ISO=REPEATABLE_READ;

BEGIN ISOLATION LEVEL REPEATABLE READ;

ALTER SYSTEM SET ISO=REPEATABLE_READ;

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

Which of the below are true about a Pages Item Pointer?

stored in PGDATA/itemptr directory

Each pointer uses 4 bytes

Each pointer uses 8 bytes

Also know as the pages table of contents

2 / 10

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

True

False

3 / 10

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

True

False

4 / 10

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

False

True

5 / 10

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

True

False

6 / 10

What does an Item Pointer contain?

choose 3

tuple length

tuple xid

tuple status

tuple offset from the start of the page

7 / 10

Tuples can also be referred to as columns?

True

False

8 / 10

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

True

False

9 / 10

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

False

True

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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