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

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

2 / 20

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

GROW

BAKE

BREAD

TOAST

3 / 20

What is the default standard size for a fork file?

5GB

5MB

1GB

1MB

4 / 20

What is the purpose of autovacuum?

Removes stale data from tables and indexes

Rebuilds indexes with b level greater than 2

Performs a backup of WAL logs

Deletes old logs and traces on disk

5 / 20

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 user tables that are common to the whole cluster

stores WAL logs used for global replication

6 / 20

What is the purpose of wal writer?

collects usage statistics for the instance.

executes checkpoints

flushes dirty pages to disk.

writes WAL entries to disk

7 / 20

A schema can belong to more than one database?

True

False

8 / 20

Which fork keeps track of available space within pages?

vacuum space map

free space map

wal space map

used space map

9 / 20

System Catalog tables begin with which prefix?

sys_

dba_

pg_

cat_

10 / 20

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

11 / 20

What is the purpose of the visibility map?

provides the data decryption key

shows a page to be vacuumed or frozen

shows referential relationships for tables

provides an audit trail for the database

12 / 20

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

False

True

13 / 20

What is the purpose of the template0 database?

Useful for creating development schemas

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

Useful for Postgres support Services to debug issues

No such database

14 / 20

Postgres by default has built in connection pooling abilities?

False

True

15 / 20

What column in system catalogs servers as the Primary Key

obj

oid#

obj#

oid

16 / 20

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

PGDATA

PGBASE

PGTIPS

PGCORE

17 / 20

When PostgreSQL is running what can it be referred to as?

Choose 2 option

Quorum

Aurora

Instance

Postgres Server

18 / 20

What is another name for the postgres process?

postmaster

masterprocess

aurora

postmanager

19 / 20

A single Postgres Instance can server only one database?

False

True

20 / 20

Which fork is specific for unlogged tables?

free space map

Initialization fork

visiblilty map

Main fork

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

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

choose 3

Read Committed

Repeatable Read

Serializable

Read Uncommitted

2 / 10

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

False

True

3 / 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.

4 / 10

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 also queries this same data.

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.

5 / 10

What is the default Isolation Level?

Read Committed

Repeatable Read

Read Uncommitted

Serializable

6 / 10

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

SAFE

SOC2

ACID

HIPPA

7 / 10

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

8 / 10

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

True

False

9 / 10

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

Repeatable Read

Read Uncommitted

Read Committed

Serializable

10 / 10

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

SET ISO=REPEATABLE_READ;

BEGIN ISOLATION LEVEL REPEATABLE READ;

CREATE EXTENSTION 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

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

True

False

2 / 10

Page header sizes can be easily displayed using the <choose from answers> extension

pagedetect

pagesize

pageheadinfo

pageinspect

3 / 10

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

False

True

4 / 10

Page free space can often become fragmented?

True

False

5 / 10

Information about subtransactions is stored under?

PGDATA/pg_subtrans

PGDATA/subtrans

PGDATA/pg_min

PGDATA/pg_xid

6 / 10

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

True

False

7 / 10

Each page has a layer that usually consists of?

choose 2

free space

flashback block

page header

undo segment

8 / 10

UPDATE can be regarded as which 2 separate operations?

DELETE

INSERT

COMMIT

MERGE

9 / 10

CLOG files are stored in which directory?

PGDATA/pg_clog

PGDATA/pg_xact

PGDATA/clog

PGDATA/pg_commit

10 / 10

What does an Item Pointer contain?

choose 3

tuple offset from the start of the page

tuple status

tuple xid

tuple length

Your score is

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