From ac83a119c565bda7721cd1534c673baba93bfdd1 Mon Sep 17 00:00:00 2001 From: Tim Hunt Date: Thu, 26 Jun 2014 16:45:05 +0100 Subject: [PATCH] MDL-45594 simplify message_get_recent_conversations SQL I am pretty sure that this new SQL is logically equivalent to the original, and it passes Mark's unit tests. However, it is hard to be 100% sure. --- message/lib.php | 102 +++++++++++++++++++++--------------------------- 1 file changed, 44 insertions(+), 58 deletions(-) diff --git a/message/lib.php b/message/lib.php index a3bb7cb69d3..18d4794343d 100644 --- a/message/lib.php +++ b/message/lib.php @@ -704,70 +704,56 @@ function message_print_search($advancedsearch = false, $user1=null) { function message_get_recent_conversations($user, $limitfrom=0, $limitto=100) { global $DB; - $userfields = user_picture::fields('u', array('lastaccess')); - //This query retrieves the last message received from and sent to each user - //It unions that data then, within that set, it finds the most recent message you've exchanged with each user over all - //It then joins with some other tables to get some additional data we need + $userfields = user_picture::fields('otheruser', array('lastaccess')); - //message ID is used instead of timecreated as it should sort the same and will be much faster + // This query retrieves the most recent message received from or sent to + // seach other user. + // + // If two messages have the same timecreated, we take the one with the + // larger id. + // + // There is a separate query for read and unread messages as they are stored + // in different tables. They were originally retrieved in one query but it + // was so large that it was difficult to be confident in its correctness. + $sql = "SELECT $userfields, + message.id as mid, message.notification, message.smallmessage, message.fullmessage, + message.fullmessagehtml, message.fullmessageformat, message.timecreated, + contact.id as contactlistid, contact.blocked - //There is a separate query for read and unread queries as they are stored in different tables - //They were originally retrieved in one query but it was so large that it was difficult to be confident in its correctness - $sql = "SELECT $userfields, mr.id as mid, mr.notification, mr.smallmessage, mr.fullmessage, mr.fullmessagehtml, mr.fullmessageformat, mr.timecreated, mc.id as contactlistid, mc.blocked - FROM {message_read} mr - JOIN ( - SELECT messages.userid AS userid, MAX(messages.mid) AS mid - FROM ( - SELECT mr1.useridto AS userid, MAX(mr1.id) AS mid - FROM {message_read} mr1 - WHERE mr1.useridfrom = :userid1 - AND mr1.notification = 0 - GROUP BY mr1.useridto - UNION - SELECT mr2.useridfrom AS userid, MAX(mr2.id) AS mid - FROM {message_read} mr2 - WHERE mr2.useridto = :userid2 - AND mr2.notification = 0 - GROUP BY mr2.useridfrom - ) messages - GROUP BY messages.userid - ) messages2 ON mr.id = messages2.mid AND (mr.useridto = messages2.userid OR mr.useridfrom = messages2.userid) - JOIN {user} u ON u.id = messages2.userid - LEFT JOIN {message_contacts} mc ON mc.userid = :userid3 AND mc.contactid = u.id - WHERE u.deleted = '0' - ORDER BY mr.id DESC"; - $params = array('userid1' => $user->id, 'userid2' => $user->id, 'userid3' => $user->id); - $read = $DB->get_records_sql($sql, $params, $limitfrom, $limitto); + FROM {message_read} message + JOIN {user} otheruser ON otheruser.id = CASE + WHEN message.useridto = :userid1 THEN message.useridfrom + ELSE message.useridto END + LEFT JOIN {message_contacts} contact ON contact.userid = :userid2 AND contact.contactid = otheruser.id - $sql = "SELECT $userfields, m.id as mid, m.notification, m.smallmessage, m.fullmessage, m.fullmessagehtml, m.fullmessageformat, m.timecreated, mc.id as contactlistid, mc.blocked - FROM {message} m - JOIN ( - SELECT messages.userid AS userid, MAX(messages.mid) AS mid - FROM ( - SELECT m1.useridto AS userid, MAX(m1.id) AS mid - FROM {message} m1 - WHERE m1.useridfrom = :userid1 - AND m1.notification = 0 - GROUP BY m1.useridto - UNION - SELECT m2.useridfrom AS userid, MAX(m2.id) AS mid - FROM {message} m2 - WHERE m2.useridto = :userid2 - AND m2.notification = 0 - GROUP BY m2.useridfrom - ) messages - GROUP BY messages.userid - ) messages2 ON m.id = messages2.mid AND (m.useridto = messages2.userid OR m.useridfrom = messages2.userid) - JOIN {user} u ON u.id = messages2.userid - LEFT JOIN {message_contacts} mc ON mc.userid = :userid3 AND mc.contactid = u.id - WHERE u.deleted = '0' - ORDER BY m.id DESC"; - $unread = $DB->get_records_sql($sql, $params, $limitfrom, $limitto); + WHERE otheruser.deleted = 0 + AND (message.useridto = :userid3 OR message.useridfrom = :userid4) + AND message.notification = 0 + AND NOT EXISTS ( + SELECT 1 + FROM {message_read} othermessage + WHERE ((othermessage.useridto = :userid5 AND othermessage.useridfrom = otheruser.id) OR + (othermessage.useridfrom = :userid6 AND othermessage.useridto = otheruser.id)) + AND (othermessage.timecreated > message.timecreated OR ( + othermessage.timecreated = message.timecreated AND othermessage.id > message.id)) + ) + + ORDER BY message.timecreated DESC"; + $params = array('userid1' => $user->id, 'userid2' => $user->id, 'userid3' => $user->id, + 'userid4' => $user->id, 'userid5' => $user->id, 'userid6' => $user->id); + $read = $DB->get_records_sql($sql, $params, $limitfrom, $limitto); + + // We want to get the messages that have not been read. These are stored in the 'message' table. It is the + // exact same query as the one above, except for the table we are querying. So, simply replace references to + // the 'message_read' table with the 'message' table. + $sql = str_replace('{message_read}', '{message}', $sql); + $unread = $DB->get_records_sql($sql, $params, $limitfrom, $limitto); $conversations = array(); - //Union the 2 result sets together looking for the message with the most recent timecreated for each other user - //$conversation->id (the array key) is the other user's ID + // Union the 2 result sets together looking for the message with the most + // recent timecreated for each other user. + // $conversation->id (the array key) is the other user's ID. $conversation_arrays = array($unread, $read); foreach ($conversation_arrays as $conversation_array) { foreach ($conversation_array as $conversation) {