Oracle的PL/SQL提供了Pipelined Table Functions特性用于把多行数据返回到调用者，可以有效的提升性能。 在PostgreSQL中，可以通过在函数中利用SETOF或者RETURN NEXT来实现。 **Oracle** 创建数据表，插入数据 ``` TEST-orcl@DESKTOP-V430TU3>drop table t_piperow; drop table t_piperow * ERROR at line 1: ORA-00942: table or view does not exist TEST-orcl@DESKTOP-V430TU3>create table t_piperow(id int,c1 timestamp ,c2 varchar2(20),c3 number); Table created. TEST-orcl@DESKTOP-V430TU3> TEST-orcl@DESKTOP-V430TU3>insert into t_piperow(id,c1,c2,c3) 2 select rownum,sysdate,'test'||rownum,123455.55 from dba_objects where rownum <= 500; 500 rows created. TEST-orcl@DESKTOP-V430TU3>commit; Commit complete. TEST-orcl@DESKTOP-V430TU3> ``` 创建Type ``` TEST-orcl@DESKTOP-V430TU3>CREATE OR REPLACE TYPE rec_t_piperow AS OBJECT(id int,c1 timestamp ,c2 varchar2(20),c3 number); 2 / Type created. TEST-orcl@DESKTOP-V430TU3>CREATE OR REPLACE TYPE type_t_piperow AS TABLE OF rec_t_piperow; 2 / Type created. ``` 函数实现 ``` TEST-orcl@DESKTOP-V430TU3>CREATE OR REPLACE FUNCTION func_piperow_demo1 RETURN type_t_piperow PIPELINED IS 2 BEGIN 3 FOR rec in (select * from t_piperow) LOOP 4 PIPE ROW (rec_t_piperow(rec.id,rec.c1,rec.c2,rec.c3)); 5 END LOOP; 6 RETURN; 7 END; 8 / Function created. ``` 查询数据 ``` TEST-orcl@DESKTOP-V430TU3>column c3 format 9999999999999.9999 TEST-orcl@DESKTOP-V430TU3>select * from table(func_piperow_demo1()) where rownum < 5; ID C1 C2 C3 ---------- -------------------- -------------------- ------------------- 1 31-OCT-19 10.50.38.0 test1 123455.5500 00000 AM 2 31-OCT-19 10.50.38.0 test2 123455.5500 00000 AM 3 31-OCT-19 10.50.38.0 test3 123455.5500 00000 AM 4 31-OCT-19 10.50.38.0 test4 123455.5500 00000 AM ``` **PostgreSQL** 下面来看看PG的实现，创建表，插入数据 ``` [local]:5432 pg12@testdb=# drop table if exists t_piperow; DROP TABLE Time: 5.255 ms [local]:5432 pg12@testdb=# create table t_piperow(id int,c1 timestamp ,c2 varchar(20),c3 float); CREATE TABLE Time: 4.711 ms [local]:5432 pg12@testdb=# [local]:5432 pg12@testdb=# insert into t_piperow(id,c1,c2,c3) pg12@testdb-# select x,now(),'test'||x,123455.55 from generate_series(1,500) x; INSERT 0 500 Time: 10.183 ms [local]:5432 pg12@testdb=# [local]:5432 pg12@testdb=# ``` 函数实现 第一种方式，使用SQL： ``` [local]:5432 pg12@testdb=# CREATE OR REPLACE FUNCTION func_piperow_demo1() RETURNS SETOF PUBLIC.t_piperow pg12@testdb-# AS pg12@testdb-# $$ pg12@testdb$# SELECT * FROM t_piperow; pg12@testdb$# $$ pg12@testdb-# LANGUAGE SQL; CREATE FUNCTION Time: 1.341 ms [local]:5432 pg12@testdb=# [local]:5432 pg12@testdb=# select func_piperow_demo1() limit 5; func_piperow_demo1 -------------------------------------------------- (1,"2019-10-31 11:09:27.222996",test1,123455.55) (2,"2019-10-31 11:09:27.222996",test2,123455.55) (3,"2019-10-31 11:09:27.222996",test3,123455.55) (4,"2019-10-31 11:09:27.222996",test4,123455.55) (5,"2019-10-31 11:09:27.222996",test5,123455.55) (5 rows) Time: 1.038 ms [local]:5432 pg12@testdb=# ``` 第二种方式，使用PL/pgSQL，RETURN QUERY ``` [local]:5432 pg12@testdb=# CREATE OR REPLACE FUNCTION func_piperow_demo2() RETURNS SETOF PUBLIC.t_piperow pg12@testdb-# AS pg12@testdb-# $$ pg12@testdb$# BEGIN pg12@testdb$# RETURN QUERY SELECT * FROM t_piperow; pg12@testdb$# END; pg12@testdb$# $$ pg12@testdb-# LANGUAGE PLPGSQL; CREATE FUNCTION Time: 3.850 ms [local]:5432 pg12@testdb=# select func_piperow_demo2() limit 5; func_piperow_demo2 -------------------------------------------------- (1,"2019-10-31 11:09:27.222996",test1,123455.55) (2,"2019-10-31 11:09:27.222996",test2,123455.55) (3,"2019-10-31 11:09:27.222996",test3,123455.55) (4,"2019-10-31 11:09:27.222996",test4,123455.55) (5,"2019-10-31 11:09:27.222996",test5,123455.55) (5 rows) Time: 5.645 ms [local]:5432 pg12@testdb=# ``` 第三种方式，使用PL/pgSQL，RETURN NEXT ``` [local]:5432 pg12@testdb=# select func_piperow_demo3() limit 5; func_piperow_demo3 -------------------------------------------------- (1,"2019-10-31 11:09:27.222996",test1,123455.55) (2,"2019-10-31 11:09:27.222996",test2,123455.55) (3,"2019-10-31 11:09:27.222996",test3,123455.55) (4,"2019-10-31 11:09:27.222996",test4,123455.55) (5,"2019-10-31 11:09:27.222996",test5,123455.55) (5 rows) Time: 5.588 ms [local]:5432 pg12@testdb=# ``` **参考资料** [PostgreSQL Oracle 兼容性 之 TABLE、PIPELINED函数](https://yq.aliyun.com/articles/228257) [Pipelined in Oracle as well in PostgreSQL](http://manojadinesh.blogspot.com/2011/11/pipelined-in-oracle-as-well-in.html)