1DBLINK_GET_RESULT(3) PostgreSQL 12.2 Documentation DBLINK_GET_RESULT(3)
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6 dblink_get_result - gets an async query result
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9 dblink_get_result(text connname [, bool fail_on_error]) returns setof record
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12 dblink_get_result collects the results of an asynchronous query
13 previously sent with dblink_send_query. If the query is not already
14 completed, dblink_get_result will wait until it is.
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17 connname
18 Name of the connection to use.
19 fail_on_error
21 If true (the default when omitted) then an error thrown on the
22 remote side of the connection causes an error to also be thrown
23 locally. If false, the remote error is locally reported as a
24 NOTICE, and the function returns no rows.
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27 For an async query (that is, a SQL statement returning rows), the
28 function returns the row(s) produced by the query. To use this
29 function, you will need to specify the expected set of columns, as
30 previously discussed for dblink.
31 For an async command (that is, a SQL statement not returning rows), the
33 function returns a single row with a single text column containing the
34 command's status string. It is still necessary to specify that the
35 result will have a single text column in the calling FROM clause.
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38 This function must be called if dblink_send_query returned 1. It must
39 be called once for each query sent, and one additional time to obtain
40 an empty set result, before the connection can be used again.
41 When using dblink_send_query and dblink_get_result, dblink fetches the
43 entire remote query result before returning any of it to the local
44 query processor. If the query returns a large number of rows, this can
45 result in transient memory bloat in the local session. It may be better
46 to open such a query as a cursor with dblink_open and then fetch a
47 manageable number of rows at a time. Alternatively, use plain dblink(),
48 which avoids memory bloat by spooling large result sets to disk.
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51 contrib_regression=# SELECT dblink_connect('dtest1', 'dbname=contrib_regression');
52 dblink_connect
53 ----------------
54 OK
55 (1 row)
56 contrib_regression=# SELECT * FROM
58 contrib_regression-# dblink_send_query('dtest1', 'select * from foo where f1 < 3') AS t1;
59 t1
60 ----
61 1
62 (1 row)
63 contrib_regression=# SELECT * FROM dblink_get_result('dtest1') AS t1(f1 int, f2 text, f3 text[]);
65 f1 | f2 | f3
66 ----+----+------------
67 0 | a | {a0,b0,c0}
68 1 | b | {a1,b1,c1}
69 2 | c | {a2,b2,c2}
70 (3 rows)
71 contrib_regression=# SELECT * FROM dblink_get_result('dtest1') AS t1(f1 int, f2 text, f3 text[]);
73 f1 | f2 | f3
74 ----+----+----
75 (0 rows)
76 contrib_regression=# SELECT * FROM
78 contrib_regression-# dblink_send_query('dtest1', 'select * from foo where f1 < 3; select * from foo where f1 > 6') AS t1;
79 t1
80 ----
81 1
82 (1 row)
83 contrib_regression=# SELECT * FROM dblink_get_result('dtest1') AS t1(f1 int, f2 text, f3 text[]);
85 f1 | f2 | f3
86 ----+----+------------
87 0 | a | {a0,b0,c0}
88 1 | b | {a1,b1,c1}
89 2 | c | {a2,b2,c2}
90 (3 rows)
91 contrib_regression=# SELECT * FROM dblink_get_result('dtest1') AS t1(f1 int, f2 text, f3 text[]);
93 f1 | f2 | f3
94 ----+----+---------------
95 7 | h | {a7,b7,c7}
96 8 | i | {a8,b8,c8}
97 9 | j | {a9,b9,c9}
98 10 | k | {a10,b10,c10}
99 (4 rows)
100 contrib_regression=# SELECT * FROM dblink_get_result('dtest1') AS t1(f1 int, f2 text, f3 text[]);
102 f1 | f2 | f3
103 ----+----+----
104 (0 rows)
105PostgreSQL 12.2 2020 DBLINK_GET_RESULT(3)