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 does Postgres know which schema to use if not specified?

Directory Path

Search Path

Schema Path

Access Path

2 / 20

TOAST tables reside in a seperate schema?

False

True

3 / 20

What is the purpose of the public schema?

restricted schema for postgres internal usage only

schema used for heterogeneous replication

default schema for user objects

no such schema

4 / 20

Each Database has its own System Catalog?

True

False

5 / 20

Which fork is specific for unlogged tables?

visiblilty map

free space map

Main fork

Initialization fork

6 / 20

System Catalog tables begin with which prefix?

cat_

pg_

dba_

sys_

7 / 20

What is the purpose of the template1 database?

a template for all the other databases

No such database

database used for temporary tables

regular database that you can use at your discretion

8 / 20

What is the purpose of the template0 database?

Useful for Postgres support Services to debug issues

Useful for creating development schemas

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

No such database

9 / 20

What is the purpose of wal writer?

flushes dirty pages to disk.

writes WAL entries to disk

collects usage statistics for the instance.

executes checkpoints

10 / 20

What is the purpose of autovacuum?

Rebuilds indexes with b level greater than 2

Performs a backup of WAL logs

Deletes old logs and traces on disk

Removes stale data from tables and indexes

11 / 20

Postgres by default has built in connection pooling abilities?

True

False

12 / 20

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

13 / 20

Which of below are predefined schemas?

choose 3

pg_toast

information_schema

pg_temp

pg_schema

14 / 20

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

table map

Main fork

free space map

visiblilty map

15 / 20

What is the purpose of the visibility map?

shows referential relationships for tables

shows a page to be vacuumed or frozen

provides the data decryption key

provides an audit trail for the database

16 / 20

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

False

True

17 / 20

Users should not modify the template0 database

True

False

18 / 20

To be able to restore data consistency, Postgres maintains

rollback segments (RBS)

undo segments (UNDO)

write-ahead log (WAL)

online redo logs (ORL)

19 / 20

Postgres server spawns a new backend session for each connection?

False

True

20 / 20

A schema can belong to more than one database?

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

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

True

False

2 / 10

The SQL standard specifies three isolation levels?

True

False

3 / 10

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

SET ISO=REPEATABLE_READ;

BEGIN ISOLATION LEVEL REPEATABLE READ;

ALTER SYSTEM SET ISO=REPEATABLE_READ;

CREATE EXTENSTION REPEATABLE_READ;

4 / 10

non-repeatable read anomaly occurs when?

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 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 issue a rollback.

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

5 / 10

What is the default Isolation Level?

Read Committed

Repeatable Read

Read Uncommitted

Serializable

6 / 10

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

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

7 / 10

Data Consistency is best handled at the application layer rather than at the database layer?

False

True

8 / 10

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

False

True

9 / 10

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

Read Uncommitted

Repeatable Read

Read Committed

Serializable

10 / 10

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

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

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

CREATE

COMMIT

INSERT

DELETE

2 / 10

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

temporary XID

magic XID

heap XID

virtual XID

3 / 10

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

False

True

4 / 10

UPDATE can be regarded as which 2 separate operations?

COMMIT

DELETE

MERGE

INSERT

5 / 10

Information about subtransactions is stored under?

PGDATA/pg_xid

PGDATA/pg_subtrans

PGDATA/subtrans

PGDATA/pg_min

6 / 10

a transaction containing a savepoint is will still be considered as only a single transaction?

True

False

7 / 10

CLOG Pages are never cached in memory?

True

False

8 / 10

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

True

False

9 / 10

What does an Item Pointer contain?

choose 3

tuple offset from the start of the page

tuple length

tuple status

tuple xid

10 / 10

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

False

True

Your score is

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