執行FORALL時執行時間不同.. INSERT INTO .. VALUE

Question

我們遇到FORALL .. INSERT INTO .. VALUES語句的執行時間不同。我們創建了一個模擬行爲的測試。運行下面的腳本顯示隨機分佈的執行時間在0.5到7-8秒之間。

腳本在運行SQL Developer的客戶端上執行，並且Oracle數據庫在同一網絡上的HyperV服務器虛擬機上運行。在此VM上，分配的內存和硬盤大小看起來足夠了。

什麼可能是不同的執行時間的原因，我們有什麼可以穩定（並最小化）執行時間？

編輯：相關的性能只是FORALL .. INSERT語句需要的時間 - 在腳本中用DBMS.PUT_LINE命令清楚地顯示。創建測試數據的性能與我的問題無關！

下面是測試腳本：

DECLARE 
    SUBTYPE t_logmsg_rec IS logmsg%ROWTYPE; 
    TYPE t_logmsg_list IS TABLE OF t_logmsg_rec; 
    l_logmsg_list t_logmsg_list := t_logmsg_list(); 
    l_logmsg_rec t_logmsg_rec; 
    l_max_logmsg_key_id logmsg.KEY_ID%TYPE; 
BEGIN 
    SELECT NVL(MAX(KEY_ID),1) 
    INTO l_max_logmsg_key_id 
    FROM logmsg; 

    FOR i IN 1..10000 LOOP 
    l_max_logmsg_key_id := l_max_logmsg_key_id + 1; 
    l_logmsg_rec.key_id  := l_max_logmsg_key_id; 
    l_logmsg_rec.msg_id  := 1; 
    l_logmsg_rec.session_id := 666; 
    l_logmsg_rec.log_timestamp := current_timestamp; 
    l_logmsg_rec.log_pck  := 'perf_test'; 
    l_logmsg_rec.log_user  := 'fl'; 
    l_logmsg_rec.log_type  := 1; 
    l_logmsg_rec.log_msg  := 'test msg ' ||i; 

    l_logmsg_rec.log_apl  := 1; 

    l_logmsg_list.EXTEND; 
    l_logmsg_list(l_logmsg_list.COUNT) := l_logmsg_rec; 
    END LOOP; 

    dbms_output.put_line('Start: ' || current_timestamp); 

    FORALL l_idx IN 1 .. l_logmsg_list.COUNT 
     INSERT INTO logmsg VALUES l_logmsg_list (l_idx); 

    dbms_output.put_line('End: ' || current_timestamp); 
END; 
/

而且表的創建腳本：

CREATE TABLE "SCOTT"."LOGMSG" 
( "KEY_ID" NUMBER(38,0) NOT NULL ENABLE, 
"MSG_ID" NUMBER(38,0) NOT NULL ENABLE, 
"LOG_TYPE" NUMBER(3,0) NOT NULL ENABLE, 
"LOG_TIMESTAMP" TIMESTAMP (6) NOT NULL ENABLE, 
"LOG_USER" VARCHAR2(32 BYTE) NOT NULL ENABLE, 
"LOG_MSG" VARCHAR2(2000 BYTE), 
"LOG_APL" NUMBER(5,0), 
"LOG_ATT" "SYS"."XMLTYPE" , 
"LOG_PCK" VARCHAR2(100 BYTE), 
"SESSION_ID" NUMBER(38,0), 
CONSTRAINT "PK_LOGMSG" PRIMARY KEY ("KEY_ID") 
USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS 
STORAGE(INITIAL 81920 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 
BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT) 
TABLESPACE "SCOTT_I_TABLESPACE" ENABLE 
) SEGMENT CREATION IMMEDIATE 
PCTFREE 0 PCTUSED 40 INITRANS 1 MAXTRANS 255 
NOCOMPRESS LOGGING 
STORAGE(INITIAL 81920 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 
BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT) 
TABLESPACE "SCOTT_TABLESPACE" 
XMLTYPE COLUMN "LOG_ATT" STORE AS BASICFILE CLOB (
TABLESPACE "SCOTT_TABLESPACE" DISABLE STORAGE IN ROW CHUNK 16384 RETENTION 
NOCACHE LOGGING 
STORAGE(INITIAL 81920 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 
BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)) ; 

CREATE INDEX "SCOTT"."IX_LOGMSG_1" ON "SCOTT"."LOGMSG" ("MSG_ID") 
PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS 
STORAGE(INITIAL 81920 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 
BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT) 
TABLESPACE "SCOTT_I_TABLESPACE" ; 

CREATE INDEX "SCOTT"."IX_LOGMSG_2" ON "SCOTT"."LOGMSG" ("SESSION_ID") 
PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS 
STORAGE(INITIAL 81920 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 
BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT) 
TABLESPACE "SCOTT_I_TABLESPACE" ; 

CREATE INDEX "SCOTT"."IX_LOGMSG_3" ON "SCOTT"."LOGMSG" ("LOG_TIMESTAMP") 
PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS 
STORAGE(INITIAL 81920 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 
BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT) 
TABLESPACE "SCOTT_I_TABLESPACE" ; 

CREATE INDEX "SCOTT"."IX_LOGMSG_C1" ON "SCOTT"."LOGMSG" ("LOG_MSG") 
PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS 
STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 
BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT) 
TABLESPACE "SCOTT_I_TABLESPACE" ; 

CREATE INDEX "SCOTT"."IX_LOGMSG_C2" ON "SCOTT"."LOGMSG" ("LOG_PCK") 
PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS 
STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 
BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT) 
TABLESPACE "SCOTT_I_TABLESPACE" ; 

Answer 1

也許你可以嘗試替代，你能避免在陣列中按行人口的行。我試圖用一個批量收集操作來說明同一個例子。希望能幫助到你。

set sqlbl on; 
DECLARE 
    TYPE t_logmsg_tab IS TABLE OF log_msg%ROWTYPE; 
    lv_log_msg t_logmsg_tab; 
BEGIN 


--Since i can see only 10000 values are fetched so here we need not to use LIMIT clause but if 
--date volume is more then we need to put LIMIT clause to prevent memory overflow 

    SELECT NVL(MAX(KEY_ID) OVER(ORDER BY 1),1)+LEVEL, 
     '1' msg_id, 
     '666' session_id, 
     current_timestamp, 
     'perf_test' log_pck, 
     'f1' log_user, 
     1 log_type, 
     'test msg '||LEVEL, 
     '1' log_apl 
     BULK COLLECT INTO 
     lv_log_msg 
     FROM l_max_logmsg_key_id 
     CONNECT BY LEVEL < 10001; 

--Not required going for row by row processing will definitely take toll 
--So avoiding and performing a bulk Collect Operation 


-- SELECT NVL(MAX(KEY_ID),1) 
-- INTO l_max_logmsg_key_id 
-- FROM logmsg; 
-- 
-- FOR i IN 1..10000 LOOP 
-- l_max_logmsg_key_id := l_max_logmsg_key_id + 1; 
-- l_logmsg_rec.key_id  := l_max_logmsg_key_id; 
-- l_logmsg_rec.msg_id  := 1; 
-- l_logmsg_rec.session_id := 666; 
-- l_logmsg_rec.log_timestamp := current_timestamp; 
-- l_logmsg_rec.log_pck  := 'perf_test'; 
-- l_logmsg_rec.log_user  := 'fl'; 
-- l_logmsg_rec.log_type  := 1; 
-- l_logmsg_rec.log_msg  := 'test msg ' ||i; 
-- 
-- l_logmsg_rec.log_apl  := 1; 
-- 
-- l_logmsg_list.EXTEND; 
-- l_logmsg_list(l_logmsg_list.COUNT) := l_logmsg_rec; 
-- END LOOP; 

    IF lv_log_msg.EXISTS(1) THEN 

    dbms_output.put_line('Start: ' || current_timestamp); 

    FORALL l_idx IN lv_log_msg.FIRST .. lv_log_msg.LAST 
     INSERT INTO logmsg VALUES lv_log_msg (l_idx); 

    dbms_output.put_line('End: ' || current_timestamp); 

    END IF; 

END; 
/