SQLite在iOS9下運行「一些」查詢，查看速度比iOS8慢很多

Question

剛開始用Xcode版本7.0（7A220）完全測試我們的應用程序。它大量使用SQLite，大量查詢，插入，更新和使用視圖等。它是一個產品定價工具，它有很多行迭代，因此可以提供優惠以及各種規則和依賴關係。當被問到時它確實做了很多。在Xcode 6下，支持iOS8，性能很好。瞬間沒有問題。當運行相同的應用程序，實際編譯爲iOS8，並且已經安裝在iOS9之前的iPad上時，它運行時就像一隻蝸牛。

所以它絕對是iOS9。這是唯一不同的。所以，回到Xcode 7，我開始調試。代碼中的哪些地方，是否堅持或性能受到影響？我已經隔離了對查詢的堅持，緩慢。這是一個觀點，一個非常複雜的觀點，然而，它在iOS8上運行得非常快。它的規模相當大，如果問了我會發布它，但我的主要問題是...有什麼我需要注意的iOS9和SQLite性能？事實上，我很困惑問題是什麼。我試圖消除：

sqlite3.dylib 

並與出現在Xcode 7船庫替換它：

libsqlite3.0.tbd 

然後

libsqlite3.tbd 

但無論是幫助。

仍然運行非常緩慢。

任何任何想法？

Answer 1

OK-謝謝，以上建議。我看了一下Instruments Trace，但這並不是真的必要，因爲調試告訴我運行速度慢的確切查詢。

但我的問題的關注，爲什麼它是從iOS8上移動到iOS9將導致查詢優化器以不同的方式評估相同的查詢。它絕對如此。爲了完整性，我自己回答了這個問題，因爲我已經解決了這個問題。但是，只是因爲我不得不重新調整SQL以適應優化器現在正在做的任何事情。

有趣的是，使用中的相同SQLite庫並沒有改變。所以，我仍然不知道爲什麼遷移到iOS9會給我帶來這個問題。在下面，查詢。我不希望任何人理解它，只要說句法是可以理解的即可。但是，我改變查詢的方式是從一個嵌套選擇中取出一個SELECT（或替換）。

這幾乎就好像SQLite不喜歡iOS9下嵌套查詢的深度。當然這沒有意義。但這是我觀察到的。

NSString *view = @" CREATE VIEW IF NOT EXISTS OFF_VIEW_5_FIXED_AMT_OFF AS " 
     " SELECT OTV_OOL_OOH_SEQ_NO   AS R_OOL_OOH_SEQ_NO, " 
     "  OTV_OOL_SEQ_NO    AS R_OOL_SEQ_NO, " 
     "  OTV_OO_SEQ_NO    AS R_OO_SEQ_NO, " 
     "  AMOUNT_DUE     AS R_OOL_TOTAL_SAVINGS, " 
     "  TOTAL_PAYABLE_WITHOUT_OFFER AS R_OOL_TOTAL_PAYABLE_NO_OFFER, " 
     "  CASE " 
     "   WHEN (100.00/TOTAL_PAYABLE_WITHOUT_OFFER * AMOUNT_DUE) > 100.00 THEN " 
     "   100.00 " 
     "   ELSE " 
     "   (100.00/TOTAL_PAYABLE_WITHOUT_OFFER * AMOUNT_DUE) " 
     "  END       AS R_OOL_PICKED_PERC_OFF_ALL_ORD, " 
     "  CASE " 
     "   WHEN SUM(OFFER_PAYABLE_BY_LINE) < 0 THEN " 
     "   0.00 " 
     "   ELSE " 
     "   SUM(OFFER_PAYABLE_BY_LINE) " 
     "  END       AS R_OFFER_TOTAL_PAYABLE_BY_LINE " 
     " FROM (SELECT OTV_OOL_SEQ_NO, " 
     "    OTV_OO_SEQ_NO, " 
     "    OTV_OOL_OOH_SEQ_NO, " 
     "    (CASE " 
     "     WHEN OO_ORD_VAL_BASED_ON_PERC_YN = 'Y' THEN " 
     "     TOTAL_PAYABLE_WITHOUT_OFFER - (TOTAL_PAYABLE_WITHOUT_OFFER/100.00 * ORDER_TOTAL_TRIGGER) " 
     "     ELSE " 
     "     CASE " 
     "      WHEN OO_DISCOUNT_ENTIRE_ORDER_YN = 'Y' THEN " 
     "      ORDER_TOTAL_TRIGGER " // -- * -1 -- When actioned, this needs to be taken off the order, perhaps defined as a negative amount. 
     "      ELSE " 
     "      TOTAL_PAYABLE_WITHOUT_OFFER - ORDER_TOTAL_TRIGGER " 
     "     END " 
     "    END) * (100.00/TOTAL_PAYABLE_WITHOUT_OFFER * OTV_OOL_UNIT_PRICE)/100.00 AS OFFER_PAYABLE_BY_LINE, " 
     "    TOTAL_PAYABLE_WITHOUT_OFFER, " 
     "    ORDER_TOTAL_TRIGGER AS AMOUNT_DUE " 

     "   FROM (SELECT OTV_OOL_SEQ_NO, " 
     "      OTV_OO_SEQ_NO, " 
     "      OTV_OO_OFFER_ID, " 
     "      OTV_OOL_OOH_SEQ_NO, " 
     "      OTV_OOL_UNIT_PRICE, " 
     "      TOTAL_PAYABLE_WITHOUT_OFFER, " 
     "      OO_ORD_VAL_BASED_ON_PERC_YN, " 
     "      OO_DISCOUNT_ENTIRE_ORDER_YN, " 
     "      OTV_TRIG_VAL_ON_ENTIRE_ORD_YN, " 
     "      TOTAL_SALES_VALUE_ALL_ORDER, " 

     "      (SELECT OAOBOV_AMOUNT_OFF " 
     "       FROM OFF_AMOUNT_OFF_BY_ORDER_VALUE " 
     "       WHERE OAOBOV_OO_SEQ_NO = OTV_OO_SEQ_NO " 
     "       AND OAOBOV_TRIGGER_VALUE = " 

     "       (SELECT MAX(OAOBOV_TRIGGER_VALUE) " 
     "        FROM OFF_AMOUNT_OFF_BY_ORDER_VALUE " 
     "        WHERE OAOBOV_TRIGGER_VALUE <= CASE " 
     "          WHEN OTV_TRIG_VAL_ON_ENTIRE_ORD_YN = 'Y' THEN " 
     "          TOTAL_SALES_VALUE_ALL_ORDER " 
     "          ELSE " 
     "          TOTAL_PAYABLE_WITHOUT_OFFER " 
     "          END " 
     "        AND OAOBOV_OO_SEQ_NO = OTV_OO_SEQ_NO)) AS ORDER_TOTAL_TRIGGER " 

     "     FROM (SELECT OTV_OOL_SEQ_NO, " 
     "         OTV_OO_OFFER_ID, " 
     "         OTV_OO_SEQ_NO, " 
     "         OTV_OOL_OOH_SEQ_NO, " 
     "         OTV_OOL_UNIT_PRICE, " 
     "         OO_ORD_VAL_BASED_ON_PERC_YN, " 
     "         OO_DISCOUNT_ENTIRE_ORDER_YN, " 
     "         OTV_TRIG_VAL_ON_ENTIRE_ORD_YN, " 
     "        (SELECT SUM(OTV_OOL_UNIT_PRICE) FROM OFF_TEMP_5) AS TOTAL_PAYABLE_WITHOUT_OFFER, " 
     "         CASE " 
     "         WHEN OTV_USE_ORD_VAL_AFTER_DISC_YN = 'Y' THEN " 
     /* 
     "          (SELECT SUM(OOL_PICKED_PRICE) " 
     "          FROM OFF_ORDER_LINES " 
     "          WHERE OOL_OOH_SEQ_NO = OTV_OOL_OOH_SEQ_NO " 
     "           AND OOL_SEQ_NO NOT IN " 
     "           (SELECT OOL_OOL_SEQ_NO " 
     "            FROM OFF_CHOICE_LOCKED_CORES, " 
     "             OFF_ORDER_LINES " 
     "            WHERE OCLC_OOH_SEQ_NO = OTV_OOL_OOH_SEQ_NO " 
     "            AND OCLC_OOL_SEQ_NO = OOL_SEQ_NO " 
     "            AND OOL_DISCOUNT_ENTIRE_ORDER_YN = 'N')) " 
     */ 
     "          (SELECT OTAOV_AFTER_OFFER_ORDER_VALUE FROM OFF_TEMP_AFTER_OFFER_VALUE) " 

     "         ELSE " 
     "          (SELECT SUM(OOL_UNIT_PRICE * OOL_QTY) " 
     "          FROM OFF_ORDER_LINES OOL " 
     "          WHERE OOL_OOH_SEQ_NO = OTV_OOL_OOH_SEQ_NO " 
     "           AND OOL.OOL_LINE_TYPE_ID = 'S') " 
     "         END            AS TOTAL_SALES_VALUE_ALL_ORDER " 
     "       FROM OFF_TEMP_5)) " 
     "     WHERE ORDER_TOTAL_TRIGGER IS NOT NULL) " 

     "  GROUP BY OTV_OOL_OOH_SEQ_NO, " 
     "     OTV_OOL_SEQ_NO, " 
     "     AMOUNT_DUE, " 
     "     TOTAL_PAYABLE_WITHOUT_OFFER, " 
     "     OTV_OO_SEQ_NO "; 

因此，/ *和* /之間的灰色部分是我拿出來的。

這...

(SELECT OTAOV_AFTER_OFFER_ORDER_VALUE FROM OFF_TEMP_AFTER_OFFER_VALUE) 

...是我與取代它。在我運行視圖之前，我在上面的表中插入一行，一行，一列，然後從中選擇。所以實質上，我刪除了在引號中運行查詢的需要。

所以，我想所有這一切的結尾，對於遇到類似問題的任何人來說，我都在追查複雜性。但我仍然困惑於爲什麼它在iOS8，Xcode 6.x上完全正常。

也許它會幫助別人。