CREATE EXTENSION pg_buffercache;
select count(*) = (select setting::bigint
                   from pg_settings
                   where name = 'shared_buffers')
from pg_buffercache;
 ?column? 
----------
 t
(1 row)

select buffers_used + buffers_unused > 0,
        buffers_dirty <= buffers_used,
        buffers_pinned <= buffers_used
from pg_buffercache_summary();
 ?column? | ?column? | ?column? 
----------+----------+----------
 t        | t        | t
(1 row)

SELECT count(*) > 0 FROM pg_buffercache_usage_counts() WHERE buffers >= 0;
 ?column? 
----------
 t
(1 row)

-- Check that the functions / views can't be accessed by default. To avoid
-- having to create a dedicated user, use the pg_database_owner pseudo-role.
SET ROLE pg_database_owner;
SELECT * FROM pg_buffercache;
ERROR:  permission denied for view pg_buffercache
SELECT * FROM pg_buffercache_pages() AS p (wrong int);
ERROR:  permission denied for function pg_buffercache_pages
SELECT * FROM pg_buffercache_summary();
ERROR:  permission denied for function pg_buffercache_summary
SELECT * FROM pg_buffercache_usage_counts();
ERROR:  permission denied for function pg_buffercache_usage_counts
RESET role;
-- Check that pg_monitor is allowed to query view / function
SET ROLE pg_monitor;
SELECT count(*) > 0 FROM pg_buffercache;
 ?column? 
----------
 t
(1 row)

SELECT buffers_used + buffers_unused > 0 FROM pg_buffercache_summary();
 ?column? 
----------
 t
(1 row)

SELECT count(*) > 0 FROM pg_buffercache_usage_counts();
 ?column? 
----------
 t
(1 row)

RESET role;
------
---- Test pg_buffercache_evict* functions
------
CREATE ROLE regress_buffercache_normal;
SET ROLE regress_buffercache_normal;
-- These should fail because they need to be called as SUPERUSER
SELECT * FROM pg_buffercache_evict(1);
ERROR:  must be superuser to use pg_buffercache_evict()
SELECT * FROM pg_buffercache_evict_relation(1);
ERROR:  must be superuser to use pg_buffercache_evict_relation()
SELECT * FROM pg_buffercache_evict_all();
ERROR:  must be superuser to use pg_buffercache_evict_all()
RESET ROLE;
-- These should return nothing, because these are STRICT functions
SELECT * FROM pg_buffercache_evict(NULL);
 buffer_evicted | buffer_flushed 
----------------+----------------
                | 
(1 row)

SELECT * FROM pg_buffercache_evict_relation(NULL);
 buffers_evicted | buffers_flushed | buffers_skipped 
-----------------+-----------------+-----------------
                 |                 |                
(1 row)

-- These should fail because they are not called by valid range of buffers
-- Number of the shared buffers are limited by max integer
SELECT 2147483647 max_buffers \gset
SELECT * FROM pg_buffercache_evict(-1);
ERROR:  bad buffer ID: -1
SELECT * FROM pg_buffercache_evict(0);
ERROR:  bad buffer ID: 0
SELECT * FROM pg_buffercache_evict(:max_buffers);
ERROR:  bad buffer ID: 2147483647
-- This should fail because pg_buffercache_evict_relation() doesn't accept
-- local relations
CREATE TEMP TABLE temp_pg_buffercache();
SELECT * FROM pg_buffercache_evict_relation('temp_pg_buffercache');
ERROR:  relation uses local buffers, pg_buffercache_evict_relation() is intended to be used for shared buffers only
DROP TABLE temp_pg_buffercache;
-- These shouldn't fail
SELECT buffer_evicted IS NOT NULL FROM pg_buffercache_evict(1);
 ?column? 
----------
 t
(1 row)

SELECT buffers_evicted IS NOT NULL FROM pg_buffercache_evict_all();
 ?column? 
----------
 t
(1 row)

CREATE TABLE shared_pg_buffercache();
SELECT buffers_evicted IS NOT NULL FROM pg_buffercache_evict_relation('shared_pg_buffercache');
 ?column? 
----------
 t
(1 row)

DROP TABLE shared_pg_buffercache;
DROP ROLE regress_buffercache_normal;