\connect dblink_test_slave create table foo(f1 int, f2 text, f3 text[], primary key (f1,f2)); NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index 'foo_pkey' for table 'foo' insert into foo values(0,'a','{"a0","b0","c0"}'); insert into foo values(1,'b','{"a1","b1","c1"}'); insert into foo values(2,'c','{"a2","b2","c2"}'); insert into foo values(3,'d','{"a3","b3","c3"}'); insert into foo values(4,'e','{"a4","b4","c4"}'); insert into foo values(5,'f','{"a5","b5","c5"}'); insert into foo values(6,'g','{"a6","b6","c6"}'); insert into foo values(7,'h','{"a7","b7","c7"}'); insert into foo values(8,'i','{"a8","b8","c8"}'); insert into foo values(9,'j','{"a9","b9","c9"}'); \connect dblink_test_master -- regular old dblink select * from dblink('dbname=dblink_test_slave','select * from foo') as t(a int, b text, c text[]) where t.a > 7; a | b | c ---+---+------------ 8 | i | {a8,b8,c8} 9 | j | {a9,b9,c9} (2 rows) -- should generate "no connection available" error select * from dblink('select * from foo') as t(a int, b text, c text[]) where t.a > 7; ERROR: dblink: no connection available -- create a persistent connection select dblink_connect('dbname=dblink_test_slave'); dblink_connect ---------------- OK (1 row) -- use the persistent connection select * from dblink('select * from foo') as t(a int, b text, c text[]) where t.a > 7; a | b | c ---+---+------------ 8 | i | {a8,b8,c8} 9 | j | {a9,b9,c9} (2 rows) -- open a cursor select dblink_open('rmt_foo_cursor','select * from foo'); dblink_open ------------- OK (1 row) -- fetch some data select * from dblink_fetch('rmt_foo_cursor',4) as t(a int, b text, c text[]); a | b | c ---+---+------------ 0 | a | {a0,b0,c0} 1 | b | {a1,b1,c1} 2 | c | {a2,b2,c2} 3 | d | {a3,b3,c3} (4 rows) select * from dblink_fetch('rmt_foo_cursor',4) as t(a int, b text, c text[]); a | b | c ---+---+------------ 4 | e | {a4,b4,c4} 5 | f | {a5,b5,c5} 6 | g | {a6,b6,c6} 7 | h | {a7,b7,c7} (4 rows) -- this one only finds two rows left select * from dblink_fetch('rmt_foo_cursor',4) as t(a int, b text, c text[]); a | b | c ---+---+------------ 8 | i | {a8,b8,c8} 9 | j | {a9,b9,c9} (2 rows) -- close the cursor select dblink_close('rmt_foo_cursor'); dblink_close -------------- OK (1 row) -- should generate "cursor rmt_foo_cursor does not exist" error select * from dblink_fetch('rmt_foo_cursor',4) as t(a int, b text, c text[]); ERROR: dblink_fetch: cursor rmt_foo_cursor does not exist -- close the persistent connection select dblink_disconnect(); dblink_disconnect ------------------- OK (1 row) -- should generate "no connection available" error select * from dblink('select * from foo') as t(a int, b text, c text[]) where t.a > 7; ERROR: dblink: no connection available -- put more data into our slave table, first using arbitrary connection syntax -- but truncate the actual return value so we can use diff to check for success select substr(dblink_exec('dbname=dblink_test_slave','insert into foo values(10,''k'',''{"a10","b10","c10"}'')'),1,6); substr -------- INSERT (1 row) -- create a persistent connection select dblink_connect('dbname=dblink_test_slave'); dblink_connect ---------------- OK (1 row) -- put more data into our slave table, using persistent connection syntax -- but truncate the actual return value so we can use diff to check for success select substr(dblink_exec('insert into foo values(11,''l'',''{"a11","b11","c11"}'')'),1,6); substr -------- INSERT (1 row) -- let's see it select * from dblink('select * from foo') as t(a int, b text, c text[]); a | b | c ----+---+--------------- 0 | a | {a0,b0,c0} 1 | b | {a1,b1,c1} 2 | c | {a2,b2,c2} 3 | d | {a3,b3,c3} 4 | e | {a4,b4,c4} 5 | f | {a5,b5,c5} 6 | g | {a6,b6,c6} 7 | h | {a7,b7,c7} 8 | i | {a8,b8,c8} 9 | j | {a9,b9,c9} 10 | k | {a10,b10,c10} 11 | l | {a11,b11,c11} (12 rows) -- change some data select dblink_exec('update foo set f3[2] = ''b99'' where f1 = 11'); dblink_exec ------------- UPDATE 1 (1 row) -- let's see it select * from dblink('select * from foo') as t(a int, b text, c text[]) where a = 11; a | b | c ----+---+--------------- 11 | l | {a11,b99,c11} (1 row) -- delete some data select dblink_exec('delete from foo where f1 = 11'); dblink_exec ------------- DELETE 1 (1 row) -- let's see it select * from dblink('select * from foo') as t(a int, b text, c text[]) where a = 11; a | b | c ---+---+--- (0 rows) -- misc utilities \connect dblink_test_slave -- show the currently executing query select 'hello' as hello, dblink_current_query() as query; hello | query -------+----------------------------------------------------------- hello | select 'hello' as hello, dblink_current_query() as query; (1 row) -- list the primary key fields select * from dblink_get_pkey('foo'); position | colname ----------+--------- 1 | f1 2 | f2 (2 rows) -- build an insert statement based on a local tuple, -- replacing the primary key values with new ones select dblink_build_sql_insert('foo','1 2',2,'{"0", "a"}','{"99", "xyz"}'); dblink_build_sql_insert ----------------------------------------------------------- INSERT INTO foo(f1,f2,f3) VALUES('99','xyz','{a0,b0,c0}') (1 row) -- build an update statement based on a local tuple, -- replacing the primary key values with new ones select dblink_build_sql_update('foo','1 2',2,'{"0", "a"}','{"99", "xyz"}'); dblink_build_sql_update ---------------------------------------------------------------------------------------- UPDATE foo SET f1 = '99', f2 = 'xyz', f3 = '{a0,b0,c0}' WHERE f1 = '99' AND f2 = 'xyz' (1 row) -- build a delete statement based on a local tuple, select dblink_build_sql_delete('foo','1 2',2,'{"0", "a"}'); dblink_build_sql_delete --------------------------------------------- DELETE FROM foo WHERE f1 = '0' AND f2 = 'a' (1 row)