Po przejrzeniu innych odpowiedzi pomogło mi to zrozumieć podstawowy problem.
Zarówno tabela artykułów, jak i tabela article_images muszą mieć dodatkowy indeks.
Oto, co masz teraz:
CREATE TABLE `articles` (
`id` int(10) unsigned not null auto_increment,
`author_id` int(10) unsigned not null,
`date_created` datetime not null,
PRIMARY KEY(id)
) ENGINE=InnoDB;
CREATE TABLE `article_images` (
`article_id` int(10) unsigned not null,
`filename` varchar(100) not null,
`date_added` datetime not null,
UNIQUE INDEX(article_id, filename)
) ENGINE=InnoDB;
Oto czego potrzebujesz:
CREATE TABLE `articles` (
`id` int(10) unsigned not null auto_increment,
`author_id` int(10) unsigned not null,
`date_created` datetime not null,
PRIMARY KEY(id),
INDEX (date_created DESC)
) ENGINE=InnoDB;
CREATE TABLE `article_images` (
`article_id` int(10) unsigned not null,
`filename` varchar(100) not null,
`date_added` datetime not null,
UNIQUE INDEX (article_id, filename),
INDEX (article_id, date_added),
) ENGINE=InnoDB;
artykuły
Nowy indeks do porządkowania artykułów według daty wstawienia w porządku malejącym
article_images
Pierwszy indeks jest nadal potrzebny, ponieważ chroni on przed dołączaniem kolejnego obrazu o tej samej nazwie pliku do artykułu.
Drugi indeks ułatwi znalezienie najnowszego obrazu,
Po wprowadzeniu tych nowych indeksów oto zapytanie, które wykona Twoje licytacje:
SELECT
AAA.author_id,
AAA.date_created,
IFNULL(BBB.title,'<NO_TITLE>') title,
IFNULL(CCC.filename,'<NO-IMAGE>') filename
FROM
(
SELECT
AA.id,
AA.date_added,
BB.author_id,
BB.date_created
FROM
(
SELECT
A.id,IFNULL(MAX(B.date_added),'1900-01-01 00:00:00') date_added
FROM (SELECT id FROM articles ORDER BY date_created DESC LIMIT 40) A
LEFT JOIN article_images B ON A.id = B.article_id
GROUP BY A.id
) AA
INNER JOIN articles BB USING (id)
) AAA
LEFT JOIN article_contents BBB ON AAA.id=BBB.article_id
LEFT JOIN article_images CCC
ON (AAA.id=CCC.article_id AND AAA.date_added=CCC.date_added)
ORDER BY AAA.date_created DESC;
Celem jest najpierw utworzenie wewnętrznego podzapytania, które ma tylko 40 wierszy. To właśnie powinno przywrócić AA. Podzapytanie AAA powinno zawierać informacje o artykule oraz datę wstawienia ostatniego obrazu. Ostatni zestaw złączeń powinien łączyć 40 identyfikatorów z tytułem i obrazem. Ostatnim krokiem jest przedstawienie zestawu wyników w kolejności malejącej.
Ponieważ nie mam przykładowych danych, napisałem trzy procedury składowane w przykładowej bazie danych o nazwie stuff
1 aby zrobić stoły
DELIMITER $$
DROP PROCEDURE IF EXISTS `stuff`.`MakeTables` $$
CREATE PROCEDURE `stuff`.`MakeTables` ()
BEGIN
DROP TABLE IF EXISTS articles;
DROP TABLE IF EXISTS article_contents;
DROP TABLE IF EXISTS article_images;
CREATE TABLE `articles` (
`id` int(10) unsigned not null auto_increment,
`author_id` int(10) unsigned not null,
`date_created` datetime not null,
PRIMARY KEY(id),
INDEX (date_created DESC)
) ENGINE=InnoDB;
CREATE TABLE `article_contents` (
`article_id` int(10) unsigned not null,
`title` varchar(100) not null,
`content` text not null,
PRIMARY KEY(article_id)) ENGINE=InnoDB;
CREATE TABLE `article_images` (
`article_id` int(10) unsigned not null,
`filename` varchar(100) not null,
`date_added` datetime not null,
UNIQUE INDEX (article_id, filename),
INDEX (article_id, date_added)
) ENGINE=InnoDB;
END $$
DELIMITER ;
1, aby utworzyć dane
DELIMITER $$
DROP PROCEDURE IF EXISTS `stuff`.`LoadSampleData` $$
CREATE PROCEDURE `stuff`.`LoadSampleData` ()
BEGIN
DECLARE x,y,z INT;
SET x = 1;
WHILE x <= 100 DO
INSERT INTO articles (author_id,date_created) VALUES
(RAND() * POWER(2,31),
DATE('1970-01-01 00:00:00') + INTERVAL (RAND() * POWER(2,30)) SECOND);
SET x = x + 1;
END WHILE;
SET x = 1;
WHILE x <= 100 DO
SET y = FLOOR(RAND() * 100);
IF y >= 30 THEN
INSERT INTO article_contents
VALUES (x,
CONCAT('TITLE_',FLOOR(RAND() * POWER(2,31))),
CONCAT('CONTENT_',FLOOR(RAND() * POWER(2,31))));
END IF;
SET x = x + 1;
END WHILE;
SET x = 1;
WHILE x <= 100 DO
SELECT COUNT(1) INTO y FROM article_contents WHERE article_id = x;
IF y = 1 THEN
SET y = 0;
WHILE y < 20 DO
SET y = y + 1;
SET z = FLOOR(RAND() * 10);
IF z >= 5 THEN
INSERT INTO article_images
VALUES (x,
CONCAT('IMAGE_',FLOOR(RAND() * POWER(2,31))),
DATE('1970-01-01 00:00:00') + INTERVAL (RAND() * POWER(2,30)) SECOND);
END IF;
END WHILE;
END IF;
SET x = x + 1;
END WHILE;
SELECT COUNT(1) INTO x FROM articles;
SELECT COUNT(1) INTO y FROM article_contents;
SELECT COUNT(1) INTO z FROM article_images;
SELECT CONCAT('Articles:',x,' Titles:',y,' Images: ',z) Results;
END $$
DELIMITER ;
1, aby uruchomić zapytanie
DELIMITER $$
DROP PROCEDURE IF EXISTS `stuff`.`ShowLast40` $$
CREATE PROCEDURE `stuff`.`ShowLast40` ()
BEGIN
SELECT
AAA.author_id,
AAA.date_created,
IFNULL(BBB.title,'<NO_TITLE>') title,
IFNULL(CCC.filename,'<NO-IMAGE>') filename
FROM
(
SELECT
AA.id,
AA.date_added,
BB.author_id,
BB.date_created
FROM
(
SELECT
A.id,IFNULL(MAX(B.date_added),'1900-01-01 00:00:00') date_added
FROM (SELECT id FROM articles ORDER BY date_created DESC LIMIT 40) A
LEFT JOIN article_images B ON A.id = B.article_id
GROUP BY A.id
) AA
INNER JOIN articles BB USING (id)
) AAA
LEFT JOIN article_contents BBB ON AAA.id=BBB.article_id
LEFT JOIN article_images CCC
ON (AAA.id=CCC.article_id AND AAA.date_added=CCC.date_added)
ORDER BY AAA.date_created DESC;
END $$
DELIMITER ;
Oto przykładowe wyjście, gdy uruchomiłem go na moim pulpicie Windows (MySQL 5.5.12):
mysql> call maketables; call loadsampledata;
Query OK, 0 rows affected (0.31 sec)
+------------------------------------+
| Results |
+------------------------------------+
| Articles:100 Titles:67 Images: 666 |
+------------------------------------+
1 row in set (23.73 sec)
mysql> call showlast40;
+------------+---------------------+------------------+------------------+
| author_id | date_created | title | filename |
+------------+---------------------+------------------+------------------+
| 1576679519 | 2004-01-02 14:05:17 | TITLE_1757853515 | IMAGE_1601858163 |
| 992840519 | 2003-05-17 05:48:11 | TITLE_319026350 | IMAGE_1913708631 |
| 1366977197 | 2003-03-20 19:37:23 | <NO_TITLE> | <NO-IMAGE> |
| 1705517382 | 2003-02-07 16:48:56 | <NO_TITLE> | <NO-IMAGE> |
| 1529899841 | 2002-11-02 20:59:26 | <NO_TITLE> | <NO-IMAGE> |
| 1756824942 | 2002-08-28 16:01:59 | <NO_TITLE> | <NO-IMAGE> |
| 175825630 | 2002-05-08 13:48:56 | TITLE_240812804 | IMAGE_1214850809 |
| 757530551 | 2002-02-08 00:20:17 | TITLE_4447486 | IMAGE_1511850161 |
| 840251261 | 2002-01-25 20:06:56 | TITLE_1160842143 | IMAGE_206027488 |
| 964653347 | 2001-12-26 19:15:47 | TITLE_1552408257 | IMAGE_717719932 |
| 2106039126 | 2001-11-11 17:09:29 | <NO_TITLE> | <NO-IMAGE> |
| 2085991608 | 2001-08-01 12:48:20 | <NO_TITLE> | <NO-IMAGE> |
| 1895462094 | 2000-12-02 05:31:41 | <NO_TITLE> | <NO-IMAGE> |
| 1589384729 | 2000-04-28 23:55:50 | TITLE_1040850308 | IMAGE_1200414639 |
| 514341550 | 2000-04-20 07:25:05 | TITLE_188288840 | IMAGE_164856430 |
| 887359583 | 2000-02-13 03:30:47 | <NO_TITLE> | <NO-IMAGE> |
| 1156687499 | 1999-06-16 00:29:17 | TITLE_686398996 | IMAGE_670200418 |
| 1561242593 | 1998-12-08 05:50:17 | <NO_TITLE> | <NO-IMAGE> |
| 1117889993 | 1998-10-23 17:02:44 | TITLE_1491217221 | IMAGE_649630126 |
| 740063135 | 1998-09-16 23:52:41 | TITLE_579374776 | IMAGE_757313192 |
| 429699232 | 1998-04-19 01:41:17 | TITLE_73748980 | IMAGE_1881818111 |
| 1827051060 | 1998-02-27 01:01:50 | TITLE_1588619991 | IMAGE_1657322715 |
| 1442984429 | 1997-11-19 21:23:35 | TITLE_184173382 | IMAGE_597809368 |
| 152267158 | 1997-05-02 20:25:50 | <NO_TITLE> | <NO-IMAGE> |
| 1323598169 | 1997-03-14 16:30:38 | TITLE_1355869397 | IMAGE_1058313818 |
| 66122740 | 1997-01-05 15:12:20 | TITLE_1259073183 | IMAGE_198280936 |
| 5161474 | 1996-06-28 10:47:26 | TITLE_1876022823 | IMAGE_1138098675 |
| 1865082792 | 1996-03-01 19:09:11 | TITLE_1288151615 | IMAGE_245974646 |
| 1923481146 | 1995-08-07 00:36:11 | TITLE_922744000 | IMAGE_2067090321 |
| 1725218958 | 1995-03-18 05:15:29 | TITLE_583120586 | IMAGE_592773824 |
| 117806248 | 1995-01-05 02:34:32 | <NO_TITLE> | <NO-IMAGE> |
| 1428777335 | 1993-06-06 01:52:32 | TITLE_661148588 | IMAGE_633345518 |
| 1091245943 | 1993-06-05 05:51:47 | TITLE_1407444563 | IMAGE_538936256 |
| 2088382260 | 1993-03-25 06:03:29 | TITLE_1144364681 | IMAGE_1790013089 |
| 625878569 | 1992-12-21 07:41:26 | TITLE_1319355723 | IMAGE_921580624 |
| 110555110 | 1992-01-01 20:49:59 | <NO_TITLE> | <NO-IMAGE> |
| 1110532475 | 1991-11-20 07:19:32 | <NO_TITLE> | <NO-IMAGE> |
| 1726795146 | 1990-10-09 00:23:44 | TITLE_782624350 | IMAGE_1760322575 |
| 370183888 | 1990-03-30 15:59:17 | <NO_TITLE> | <NO-IMAGE> |
| 1497483317 | 1990-02-19 01:25:41 | TITLE_776483948 | IMAGE_665824222 |
+------------+---------------------+------------------+------------------+
40 rows in set (0.00 sec)
Wypróbuj !!!
AKTUALIZUJ
Upewniłem się, że 40 dat, które czytasz, to w rzeczywistości 40 najlepszych. Uruchomiłem zapytanie :wybierz * z artykułów ORDER BY date_created DESC; aby się upewnić.
AKTUALIZACJA 17.05.2011 14:06
mysql> call maketables; call loadsampledata;
Query OK, 0 rows affected (0.45 sec)
+-------------------------------------+
| Results |
+-------------------------------------+
| Articles:100 Titles:67 Images: 6739 |
+-------------------------------------+
1 row in set (3 min 45.45 sec)
Query OK, 0 rows affected (3 min 45.45 sec)
mysql> call showlast40;
+------------+---------------------+------------------+------------------+
| author_id | date_created | title | filename |
+------------+---------------------+------------------+------------------+
| 196582776 | 2004-01-05 14:09:04 | <NO_TITLE> | <NO-IMAGE> |
| 1880371016 | 2003-07-31 05:50:37 | TITLE_1191518827 | IMAGE_1562208019 |
| 22204986 | 2003-02-16 14:09:22 | <NO_TITLE> | <NO-IMAGE> |
| 355490160 | 2002-11-21 02:35:19 | <NO_TITLE> | <NO-IMAGE> |
| 869510149 | 2001-12-27 22:07:52 | TITLE_1528616779 | IMAGE_223327284 |
| 2063556512 | 2001-04-16 18:47:46 | TITLE_1839975091 | IMAGE_1282187005 |
| 529754190 | 2000-07-14 19:44:01 | TITLE_1557423205 | IMAGE_1931606737 |
| 166226262 | 1999-11-08 03:27:22 | <NO_TITLE> | <NO-IMAGE> |
| 1981417562 | 1999-09-11 12:59:10 | TITLE_198262896 | IMAGE_1491273871 |
| 831057001 | 1999-06-14 15:06:31 | TITLE_1170272131 | IMAGE_760396200 |
| 1454252623 | 1998-06-02 08:35:46 | <NO_TITLE> | <NO-IMAGE> |
| 1435450777 | 1997-11-17 18:10:34 | TITLE_482497458 | IMAGE_1331932705 |
| 1536315541 | 1997-11-02 05:24:49 | <NO_TITLE> | <NO-IMAGE> |
| 2078028530 | 1997-03-14 22:36:58 | TITLE_321332010 | IMAGE_1897983295 |
| 701651581 | 1997-01-13 22:36:58 | TITLE_1337390701 | IMAGE_1630983859 |
| 101442444 | 1996-11-22 09:40:16 | <NO_TITLE> | <NO-IMAGE> |
| 51114930 | 1996-11-20 03:24:49 | TITLE_1866751135 | IMAGE_1669595407 |
| 722056183 | 1996-08-03 15:23:01 | <NO_TITLE> | <NO-IMAGE> |
| 1178720989 | 1996-06-29 22:47:19 | TITLE_579734376 | IMAGE_833229222 |
| 511355958 | 1996-03-10 09:32:46 | TITLE_1540275289 | IMAGE_1168117261 |
| 831921829 | 1996-01-31 06:36:04 | TITLE_661038882 | IMAGE_1199197195 |
| 1288455163 | 1995-08-22 00:34:25 | TITLE_1599332515 | IMAGE_822445764 |
| 1976208956 | 1995-06-02 09:23:01 | TITLE_58372998 | IMAGE_793318650 |
| 2092066982 | 1995-03-28 20:35:37 | TITLE_1693142377 | IMAGE_1176935479 |
| 1083841549 | 1994-07-11 18:46:52 | TITLE_1955674591 | IMAGE_1240485919 |
| 359037132 | 1994-07-11 02:44:19 | TITLE_713454936 | IMAGE_1072569732 |
| 1471985773 | 1994-05-10 17:08:01 | TITLE_1065017724 | IMAGE_393097704 |
| 1888864730 | 1994-01-15 17:41:28 | TITLE_1060275498 | IMAGE_230810100 |
| 1688028488 | 1993-12-28 06:36:58 | <NO_TITLE> | <NO-IMAGE> |
| 1739777948 | 1993-02-15 00:30:31 | TITLE_1226842225 | IMAGE_1615058467 |
| 445721334 | 1991-12-15 20:54:49 | TITLE_1336145587 | IMAGE_2114729323 |
| 1661002442 | 1991-06-30 05:49:34 | TITLE_151142910 | IMAGE_1623325381 |
| 2092223006 | 1991-06-13 13:15:58 | TITLE_33175860 | IMAGE_1225117771 |
| 1553434585 | 1991-01-12 03:34:25 | TITLE_728483442 | IMAGE_1954153339 |
| 528544608 | 1990-11-10 08:21:04 | <NO_TITLE> | <NO-IMAGE> |
| 1043927395 | 1990-10-05 00:48:49 | TITLE_304307448 | IMAGE_1702062493 |
| 1685702960 | 1990-04-28 05:44:19 | TITLE_1909853341 | IMAGE_263553036 |
| 1392428383 | 1990-03-07 15:08:46 | <NO_TITLE> | <NO-IMAGE> |
| 643714153 | 1990-02-14 08:32:10 | TITLE_837416724 | IMAGE_1673964259 |
| 2132028206 | 1989-09-28 16:04:07 | TITLE_614908878 | IMAGE_1362210487 |
+------------+---------------------+------------------+------------------+
40 rows in set (0.01 sec)
Wszystko działa tak, jak publikowałem wcześniej, nawet z większym zestawem zdjęć. Oto zapytanie z procedury przechowywanej ShowLast40:
SELECT
AAA.author_id,
AAA.date_created,
IFNULL(BBB.title,'<NO_TITLE>') title,
IFNULL(CCC.filename,'<NO-IMAGE>') filename
FROM
(
SELECT
AA.id,
AA.date_added,
BB.author_id,
BB.date_created
FROM
(
SELECT
A.id,IFNULL(MAX(B.date_added),'1900-01-01 00:00:00') date_added
FROM (SELECT id FROM articles ORDER BY date_created DESC LIMIT 40) A
LEFT JOIN article_images B ON A.id = B.article_id
GROUP BY A.id
) AA
INNER JOIN articles BB USING (id)
) AAA
LEFT JOIN article_contents BBB ON AAA.id=BBB.article_id
LEFT JOIN article_images CCC
ON (AAA.id=CCC.article_id AND AAA.date_added=CCC.date_added)
ORDER BY AAA.date_created DESC;
AKTUALIZACJA 17.05.2011 15:16
Dla śmiechu zwiększyłem próbkę i ponownie ją uruchomiłem. Ta sama szybkość zapytań.
mysql> call maketables; call loadsampledata; call showlast40;
Query OK, 0 rows affected (0.38 sec)
+----------------------------------------+
| Results |
+----------------------------------------+
| Articles:1000 Titles:886 Images: 88596 |
+----------------------------------------+
1 row in set (51 min 22.29 sec)
Query OK, 0 rows affected (51 min 22.29 sec)
+------------+---------------------+------------------+------------------+
| author_id | date_created | title | filename |
+------------+---------------------+------------------+------------------+
| 1464539515 | 2004-01-07 22:45:04 | TITLE_676010724 | IMAGE_1877060293 |
| 272558724 | 2004-01-03 23:44:19 | TITLE_1213504045 | IMAGE_550812606 |
| 2000476448 | 2003-12-28 18:05:10 | TITLE_1762951489 | IMAGE_1201290847 |
| 955209697 | 2003-12-25 00:55:43 | TITLE_1064749344 | IMAGE_1335865507 |
| 1657429856 | 2003-12-19 01:03:13 | TITLE_1931852743 | IMAGE_905288424 |
| 759381001 | 2003-11-12 10:46:52 | TITLE_878255772 | IMAGE_2014780795 |
| 1269478951 | 2003-11-06 02:06:22 | TITLE_2026098781 | IMAGE_982272966 |
| 1049672131 | 2003-10-04 20:55:34 | TITLE_2043080215 | IMAGE_987859662 |
| 1429108729 | 2003-09-16 19:07:52 | TITLE_424483080 | IMAGE_35379150 |
| 1672198676 | 2003-09-13 11:49:52 | TITLE_1131552745 | IMAGE_875049630 |
| 1645878842 | 2003-08-24 13:42:04 | TITLE_1077302833 | IMAGE_702269538 |
| 172347180 | 2003-08-21 14:26:37 | TITLE_558691044 | IMAGE_1091183587 |
| 1137674509 | 2003-08-15 08:44:37 | TITLE_1982979709 | IMAGE_1234487941 |
| 282998112 | 2003-08-05 10:01:34 | TITLE_353831568 | IMAGE_738487608 |
| 246145344 | 2003-08-02 00:42:31 | TITLE_376954044 | IMAGE_1279375459 |
| 218409162 | 2003-07-14 02:55:16 | TITLE_1932540991 | IMAGE_1078689211 |
| 593263087 | 2003-07-12 22:47:01 | TITLE_1604012533 | IMAGE_834822870 |
| 2115914174 | 2003-07-06 03:06:31 | TITLE_1268165545 | IMAGE_1068632322 |
| 552557275 | 2003-07-01 16:45:22 | TITLE_2022112717 | IMAGE_1410588295 |
| 1500437041 | 2003-06-29 20:05:19 | TITLE_35559258 | IMAGE_159953586 |
| 1098371257 | 2003-06-09 07:29:37 | TITLE_1694076415 | IMAGE_1409619391 |
| 1570373503 | 2003-05-22 16:45:04 | TITLE_125157894 | IMAGE_723393492 |
| 1330507411 | 2003-05-05 21:40:07 | TITLE_1571250589 | IMAGE_701840418 |
| 1666035620 | 2003-04-26 02:51:40 | TITLE_504713706 | IMAGE_1410357553 |
| 1458179791 | 2003-04-19 05:34:25 | <NO_TITLE> | <NO-IMAGE> |
| 1365758305 | 2003-03-28 10:09:58 | TITLE_704554170 | IMAGE_2085080137 |
| 2131082774 | 2003-03-26 16:43:25 | TITLE_1411034929 | IMAGE_303539208 |
| 103396632 | 2003-02-14 09:11:28 | TITLE_915927396 | IMAGE_1381045723 |
| 396479202 | 2003-02-01 15:51:40 | <NO_TITLE> | <NO-IMAGE> |
| 2019916250 | 2003-01-30 00:44:46 | <NO_TITLE> | <NO-IMAGE> |
| 431091906 | 2003-01-29 13:08:37 | <NO_TITLE> | <NO-IMAGE> |
| 705166549 | 2003-01-23 21:37:07 | TITLE_1530318643 | IMAGE_257673696 |
| 1278327049 | 2002-12-31 16:39:40 | TITLE_772845324 | IMAGE_1355754913 |
| 1871174528 | 2002-12-30 19:03:40 | TITLE_65725764 | IMAGE_522904938 |
| 611892727 | 2002-12-22 10:19:07 | TITLE_333758274 | IMAGE_734815032 |
| 758497849 | 2002-12-04 15:05:10 | TITLE_129140574 | IMAGE_244407066 |
| 518111034 | 2002-10-17 16:38:10 | TITLE_1976498683 | IMAGE_2008599775 |
| 1737725786 | 2002-10-15 23:52:52 | TITLE_1441053871 | IMAGE_1595265847 |
| 1206055789 | 2002-10-03 22:07:52 | TITLE_562697952 | IMAGE_198940092 |
| 702790153 | 2002-08-31 17:37:16 | TITLE_1788304903 | IMAGE_1212944101 |
+------------+---------------------+------------------+------------------+
40 rows in set (0.01 sec)
Query OK, 0 rows affected (0.01 sec)
AKTUALIZACJA 17.05.2011 15:40
Oto nowe dane wyjściowe zawierające datę ostatniego obrazu:
mysql> call showlast40;
+------------+---------------------+------------------+------------------+---------------------+
| author_id | date_created | title | filename | image_date |
+------------+---------------------+------------------+------------------+---------------------+
| 1464539515 | 2004-01-07 22:45:04 | TITLE_676010724 | IMAGE_1877060293 | 2003-10-16 02:06:58 |
| 272558724 | 2004-01-03 23:44:19 | TITLE_1213504045 | IMAGE_550812606 | 2003-12-28 07:25:43 |
| 2000476448 | 2003-12-28 18:05:10 | TITLE_1762951489 | IMAGE_1201290847 | 2003-08-31 16:56:01 |
| 955209697 | 2003-12-25 00:55:43 | TITLE_1064749344 | IMAGE_1335865507 | 2003-11-11 18:37:07 |
| 1657429856 | 2003-12-19 01:03:13 | TITLE_1931852743 | IMAGE_905288424 | 2003-09-26 07:20:01 |
| 759381001 | 2003-11-12 10:46:52 | TITLE_878255772 | IMAGE_2014780795 | 2003-09-30 06:54:40 |
| 1269478951 | 2003-11-06 02:06:22 | TITLE_2026098781 | IMAGE_982272966 | 2003-07-28 11:59:10 |
| 1049672131 | 2003-10-04 20:55:34 | TITLE_2043080215 | IMAGE_987859662 | 2003-11-19 05:26:37 |
| 1429108729 | 2003-09-16 19:07:52 | TITLE_424483080 | IMAGE_35379150 | 2003-11-18 22:17:55 |
| 1672198676 | 2003-09-13 11:49:52 | TITLE_1131552745 | IMAGE_875049630 | 2003-06-08 00:42:58 |
| 1645878842 | 2003-08-24 13:42:04 | TITLE_1077302833 | IMAGE_702269538 | 2002-04-02 01:21:49 |
| 172347180 | 2003-08-21 14:26:37 | TITLE_558691044 | IMAGE_1091183587 | 2003-08-13 08:30:22 |
| 1137674509 | 2003-08-15 08:44:37 | TITLE_1982979709 | IMAGE_1234487941 | 2003-12-17 11:53:28 |
| 282998112 | 2003-08-05 10:01:34 | TITLE_353831568 | IMAGE_738487608 | 2003-11-08 22:03:22 |
| 246145344 | 2003-08-02 00:42:31 | TITLE_376954044 | IMAGE_1279375459 | 2003-12-05 02:30:49 |
| 218409162 | 2003-07-14 02:55:16 | TITLE_1932540991 | IMAGE_1078689211 | 2003-07-14 15:59:37 |
| 593263087 | 2003-07-12 22:47:01 | TITLE_1604012533 | IMAGE_834822870 | 2003-09-02 05:48:22 |
| 2115914174 | 2003-07-06 03:06:31 | TITLE_1268165545 | IMAGE_1068632322 | 2003-04-28 16:29:01 |
| 552557275 | 2003-07-01 16:45:22 | TITLE_2022112717 | IMAGE_1410588295 | 2003-11-01 01:55:16 |
| 1500437041 | 2003-06-29 20:05:19 | TITLE_35559258 | IMAGE_159953586 | 2003-08-02 10:34:07 |
| 1098371257 | 2003-06-09 07:29:37 | TITLE_1694076415 | IMAGE_1409619391 | 2004-01-07 01:00:13 |
| 1570373503 | 2003-05-22 16:45:04 | TITLE_125157894 | IMAGE_723393492 | 2003-09-26 23:22:43 |
| 1330507411 | 2003-05-05 21:40:07 | TITLE_1571250589 | IMAGE_701840418 | 2003-11-19 20:57:31 |
| 1666035620 | 2003-04-26 02:51:40 | TITLE_504713706 | IMAGE_1410357553 | 2003-11-18 01:30:04 |
| 1458179791 | 2003-04-19 05:34:25 | <NO_TITLE> | <NO-IMAGE> | <NO-IMAGE-DATE> |
| 1365758305 | 2003-03-28 10:09:58 | TITLE_704554170 | IMAGE_2085080137 | 2003-11-11 16:35:19 |
| 2131082774 | 2003-03-26 16:43:25 | TITLE_1411034929 | IMAGE_303539208 | 2003-05-14 12:59:37 |
| 103396632 | 2003-02-14 09:11:28 | TITLE_915927396 | IMAGE_1381045723 | 2003-12-28 18:26:28 |
| 396479202 | 2003-02-01 15:51:40 | <NO_TITLE> | <NO-IMAGE> | <NO-IMAGE-DATE> |
| 2019916250 | 2003-01-30 00:44:46 | <NO_TITLE> | <NO-IMAGE> | <NO-IMAGE-DATE> |
| 431091906 | 2003-01-29 13:08:37 | <NO_TITLE> | <NO-IMAGE> | <NO-IMAGE-DATE> |
| 705166549 | 2003-01-23 21:37:07 | TITLE_1530318643 | IMAGE_257673696 | 2003-08-23 19:06:22 |
| 1278327049 | 2002-12-31 16:39:40 | TITLE_772845324 | IMAGE_1355754913 | 2003-12-22 16:40:25 |
| 1871174528 | 2002-12-30 19:03:40 | TITLE_65725764 | IMAGE_522904938 | 2003-09-06 07:08:01 |
| 611892727 | 2002-12-22 10:19:07 | TITLE_333758274 | IMAGE_734815032 | 2003-09-22 19:16:43 |
| 758497849 | 2002-12-04 15:05:10 | TITLE_129140574 | IMAGE_244407066 | 2003-07-15 12:38:37 |
| 518111034 | 2002-10-17 16:38:10 | TITLE_1976498683 | IMAGE_2008599775 | 2004-01-06 16:37:34 |
| 1737725786 | 2002-10-15 23:52:52 | TITLE_1441053871 | IMAGE_1595265847 | 2003-11-24 15:23:10 |
| 1206055789 | 2002-10-03 22:07:52 | TITLE_562697952 | IMAGE_198940092 | 2003-08-23 11:56:46 |
| 702790153 | 2002-08-31 17:37:16 | TITLE_1788304903 | IMAGE_1212944101 | 2003-12-19 22:56:01 |
+------------+---------------------+------------------+------------------+---------------------+
40 rows in set (0.01 sec)
Oto nowe zapytanie
SELECT
AAA.author_id,
AAA.date_created,
IFNULL(BBB.title,'<NO_TITLE>') title,
IFNULL(CCC.filename,'<NO-IMAGE>') filename,
IFNULL(CCC.date_added,'<NO-IMAGE-DATE>') image_date
FROM
(
SELECT
AA.id,
AA.date_added,
BB.author_id,
BB.date_created
FROM
(
SELECT
A.id,IFNULL(MAX(B.date_added),'1900-01-01 00:00:00') date_added
FROM (SELECT id FROM articles ORDER BY date_created DESC LIMIT 40) A
LEFT JOIN article_images B ON A.id = B.article_id
GROUP BY A.id
) AA
INNER JOIN articles BB USING (id)
) AAA
LEFT JOIN article_contents BBB ON AAA.id=BBB.article_id
LEFT JOIN article_images CCC
ON (AAA.id=CCC.article_id AND AAA.date_added=CCC.date_added)
ORDER BY AAA.date_created DESC;
Moje zapytanie robi jedną rzecz, której nikt inny nie robi:
Moje zapytanie pobiera ostatnie 40 artykułów przed dołączeniem do jakiejkolwiek innej tabeli.
Zapytania wszystkich innych najpierw łączą wszystko, a następnie próbują wykonać LIMIT 40 na dużej tabeli tymczasowej.
Czas wykonania mojego zapytania nie ma wpływu na ilość danych.
Niezależnie od wielkości próbki, którą tworzę, moje zapytanie musi być najszybsze !!!
