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
10
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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