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

Rebuilds indexes with b level greater than 2

Performs a backup of WAL logs

Removes stale data from tables and indexes

2 / 20

What is the default standard size for a fork file?

5GB

1GB

5MB

1MB

3 / 20

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

4 / 20

What is the purpose of the public schema?

schema used for heterogeneous replication

no such schema

restricted schema for postgres internal usage only

default schema for user objects

5 / 20

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

False

True

6 / 20

Who is the Author of the Postgres 14 Internals book?

Egor Rogov

Dan Brown

Sam Altman

Paul Sammy

7 / 20

What column in system catalogs servers as the Primary Key

oid#

oid

obj#

obj

8 / 20

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

pg_tablespace

pg_symlinks

pg_tabspace

pg_tblspc

9 / 20

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

Sysaux Catalog

Sysasm Catalog

Sys Catalog

System Catalog

10 / 20

What is the purpose of the visibility map?

provides the data decryption key

shows referential relationships for tables

shows a page to be vacuumed or frozen

provides an audit trail for the database

11 / 20

TOAST tables reside in a seperate schema?

True

False

12 / 20

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

BREAD

GROW

TOAST

BAKE

13 / 20

Tablespaces are used to define physical data layout?

True

False

14 / 20

Which fork contains the actual table data?

visiblilty map

table map

free space map

Main fork

15 / 20

What command is used to create the Postgres cluster?

StartNewPG

Initialize

CreateCluster

CreatePGC

16 / 20

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

PGTIPS

PGBASE

PGCORE

PGDATA

17 / 20

A schema can belong to more than one database?

False

True

18 / 20

Users should not modify the template0 database

False

True

19 / 20

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

20 / 20

A single Postgres Instance can server only one database?

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

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.

2 / 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 adds some other rows satisfying this condition and commits.

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.

3 / 10

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

False

True

4 / 10

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

HIPPA

SAFE

ACID

SOC2

5 / 10

Which parameters sets the database default isolation level?

transaction_isolation_level

default_isolation_level

active_transaction_isolation

default_transaction_isolation

6 / 10

What is the default Isolation Level?

Serializable

Repeatable Read

Read Committed

Read Uncommitted

7 / 10

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

8 / 10

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

False

True

9 / 10

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

choose 3

Read Uncommitted

Read Committed

Repeatable Read

Serializable

10 / 10

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

ALTER SYSTEM SET ISO=REPEATABLE_READ;

SET ISO=REPEATABLE_READ;

CREATE EXTENSTION REPEATABLE_READ;

BEGIN ISOLATION LEVEL 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

To identify different versions of one and the same row, PostgreSQL marks each of them with which two value?

xid

xmas

xmax

xmin

2 / 10

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

True

False

3 / 10

If a transaction is read only which kind of Transaction ID is it allocated?

temporary XID

magic XID

heap XID

virtual XID

4 / 10

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

commit log

transaction log

redo log

archive log

5 / 10

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

xid

xtime

xmin

xmax

6 / 10

CLOG files are stored in which directory?

PGDATA/clog

PGDATA/pg_clog

PGDATA/pg_commit

PGDATA/pg_xact

7 / 10

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

False

True

8 / 10

CLOG Pages are never cached in memory?

False

True

9 / 10

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

True

False

10 / 10

Which function can we use to find the current transaction ID?

pg_current_id()

pg_current_commit_id()

pg_current_xact_id()

pg_current_xmin_id()

Your score is

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