Oracle pipeline function detailed (pipelined)

1 Overview

• Function pipeline parallel execution , the function used in the normal dbms_outputoutput information, the server needs to perform other functions to return to full-time to the client. If the client needs in real time some of the information during the execution of the output function, Oracle9i later, can function pipeline ( large data processing performance ).
• Keyword pipelinedindicates that this is a function oracle conduit, its return value type must be set in function, pipe rowthe syntax is used to return the collection of individual elements , function to an empty returnsentence ends, to indicate that it has finished.

2 Examples

2.1 First create a table type

-- 直接定义类型
CREATE OR REPLACE TYPE scott.ty_list IS TABLE OF VARCHAR2(300);

-- PL/SQL 中可在 package head 中定义
-- index by ... 是为了不再手动扩充 extend(1)
TYPE scott.ty_list IS TABLE OF VARCHAR2(300) INDEX BY PLS_INTEGER;

2.2 Real-time return data

ready:

1. arraysize 是 sql*plus 中可以设置的一个参数: 表示一次可以从数据库服务端获取的记录行数
2. 首先需要设置 arraysize 为 1，否则服务器会按照默认的 15 来向客户端返回信息，这会影响我们测试效果
3. 查询命令: show arraysize
4. 设置命令: set arraysize 15

Verification: PL/SQL code:
pipeline function:

CREATE OR REPLACE FUNCTION scott.f_pipelined_test RETURN scott.ty_list
   PIPELINED IS
BEGIN
   PIPE ROW('start...');

   FOR i IN 1 .. 5 LOOP
      PIPE ROW(i || ' ' || to_char(SYSDATE, 'YYYY-MM-DD HH24:MI:SS'));
      sys.dbms_lock.sleep(1); -- 等待 1 秒
   END LOOP;

   PIPE ROW('end...');

   RETURN;
END;
/

General functions:

CREATE OR REPLACE FUNCTION scott.f_normal_test RETURN scott.ty_list IS
   v_list_out_put scott.ty_list;
BEGIN
   -- 初始化
   v_list_out_put := scott.ty_list();

   -- 扩展信息，可在 package 定义 type 时，增加 index by pls_integer 自动扩展 extend
   FOR i IN 1 .. 5 LOOP
      v_list_out_put.extend(1); -- 手动扩展
      v_list_out_put(i) := i || ' ' ||
                           to_char(SYSDATE, 'YYYY-MM-DD HH24:MI:SS');
      sys.dbms_lock.sleep(1); -- 等待 1 秒
   END LOOP;

   RETURN v_list_out_put;
END;
/

sql*plus window verification demo

hint:

1. sql*plusIt is to interact with the Oracle client tools (Oracle installed when customers bring their own end)
2. plsql Is a good visual development tool

in conclusion:

• Pipeline function: real-time output
• General function: output after the operation is completed

Dynamic icon:

3 Other examples

Serial number	description
1	The pipeline function does not support debug
2	String cutting split

I will use these for the time being, if there are any more, continue to add...

The pipeline function does not support debug:

String cutting split:

Show results:

First define the type:

CREATE TYPE scott.ty_object_map IS OBJECT
(
   v_key   NUMBER,
   v_value VARCHAR2(100)
)
;
/ 

CREATE TYPE scott.ty_table_map IS TABLE OF scott.ty_object_map;
/

-- 删除type、若需要
DROP TYPE scott.ty_table_map;
DROP TYPE scott.ty_object_map;

package head：

CREATE OR REPLACE PACKAGE scott.pkg_char_handle_util IS

   FUNCTION f_split_string(p_string    IN VARCHAR2,
                           p_delimiter IN VARCHAR2) RETURN scott.ty_table_map
      PIPELINED;
END pkg_char_handle_util;
/

package body：

CREATE OR REPLACE PACKAGE BODY scott.pkg_char_handle_util IS

   --************************************************
   -- 功能: 切割字符串
   -- 参数: p_string 字符串
   --       p_delimiter 分隔符
   -- 返回值: table 类型
   --************************************************
   FUNCTION f_split_string(p_string    IN VARCHAR2,
                           p_delimiter IN VARCHAR2) RETURN scott.ty_table_map
      PIPELINED IS
      v_length     PLS_INTEGER := length(p_string); -- 字符串长度
      v_start      PLS_INTEGER := 1; -- 字符开始位置
      v_index      PLS_INTEGER; -- 下标
      v_key        PLS_INTEGER := 1; -- 截取后，字符串的个数
      v_object_map scott.ty_object_map;
   BEGIN
      WHILE (v_start <= v_length) LOOP
         -- 获取符合条件的 第一个下标
         v_index := instr(p_string, p_delimiter, v_start);
      
         IF v_index = 0 THEN
            -- 没有符合条件的记录，直接打印，如 string = 'a', 直接打印 a
            v_object_map := scott.ty_object_map(v_key,
                                                substr(p_string, v_start));
            PIPE ROW(v_object_map);
            RETURN;
         ELSE
            -- 否则，循环截取打印
            v_object_map := scott.ty_object_map(v_key,
                                                substr(p_string,
                                                       v_start,
                                                       v_index - v_start));
            PIPE ROW(v_object_map);
            
            -- 循环判断依据: 每次 '分隔符' 后 '第一个字符'
            v_start := v_index + 1;
         END IF;
      
         -- 个数递增
         v_key := v_key + 1;
      END LOOP;
   
      RETURN;
   END f_split_string;
END pkg_char_handle_util;
/