PGCONF.EU 2017 #1

What is returned with:

SELECT NULL = NULL OR TRUE;

True

False

NULL

Exception is raised

What is returned with:
SELECT 3 ORDER BY 1 LIMIT 2;

No rows

One row with 3

Two rows with 1,2

Exception is raised

How to check if value is NULL:

COALESCE(value, default) = default

Value = NULL

ISNULL(value)

ULLIF(value)

Which statement is true:

Pg_statistic is a materialized view and pg_stats is a view

Pg_stats is a table and pg_statistic is a materialized view

Pg_statistic is a table and pg_stats is a view

Pg_statistic is a table and pg_stats is a materialized view

How to set WAL size:

Wal_size in conf file

Min_wal_size in conf file

Max_wal_size in conf file

Change XLOG_SEG_SIZE and recompile postgres

What is fillfactor when you create table:

It defines fill factor inside page so that tuple updates may land in the same page

It defines fill factor inside table so if you bloat your table over that value you will get warning

It defines ratio between table size and its all indexes

It default the threshold for autovacuum

With inheritance of which is true:

Child tables are scanned when parent table is scanned

Only child tables can have data

All child tables use the same indexes are parent table

Child tables cannot have additional columns

What is the difference between table and materialized view?

Table is persisted

You can add columns to table

Materialized view content will never change

You can create indexes for table

Which is not a postgres process name:

Executor

Logger

Writer

Wal receiver

How to create user in PostgreSQL?

CREATE ROLE

CREATE LOGIN

CREATE DOMAIN

CREATE OPERATOR

Which lock is conflicting with ROW SHARE:

SHARE UPDATE EXCLUSIVE

ROW SHARE

ACCESS EXCLUSIVE

ROW EXCLUSIVE

What are advisory locks

Extremely rare system locks

Locks on whole schema

States inbetween locks

Locks with meaning in application

Replication lag may not be caused by:

Deadlocks

High cpu usage

High disk usage

High network usage

Which is not an option of EXPLAIN?

VERBOSE

COSTS

COMPLEXITY

TIMING

Which is not an auth method in pg_hba.conf file?

Block

Trust

Ldap

Cert

Which version of PostgreSQL introduces CREATE STATISTICS:

9.0

9.4

9.6

Which version of PostgreSQL introduces CREATE TRIGGER:

7.1

8.0

8.4

9.0

To which you cannot grant privilege:

SELECT

DROP

TRUNCATE

CONNECT

Which is not an ISOLATION LEVEL?

SERIALIZABLE

REPEATABLE LOOKUP

READ COMMITTED

READ UNCOMMITTED

Which is not a bgwriter setting?

Bgwriter_delay

Bgwriter_nap_time

Bgwriter_lru_maxpages

Bgwriter_lru_multiplier

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