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MDL-68829 user: Update participants SQL for Oracle/MSSQL compatibility

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This refactors the SQL to join on a distinct list of users, removing
the need for GROUP BY statements, and fixing the related errors in
Oracle/MSSQL
This commit is contained in:
Michael Hawkins 2020-05-27 11:19:46 +08:00 committed by Eloy Lafuente (stronk7)
parent 8e1b43f0d5
commit a4bd55725b
1 changed files with 68 additions and 34 deletions
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102
user/classes/table/participants_search.php
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@ -95,14 +95,26 @@ class participants_search {
global $DB;
[
'select' => $select,
'from' => $from,
'where' => $where,
'subqueryalias' => $subqueryalias,
'outerselect' => $outerselect,
'innerselect' => $innerselect,
'outerjoins' => $outerjoins,
'innerjoins' => $innerjoins,
'outerwhere' => $outerwhere,
'innerwhere' => $innerwhere,
'params' => $params,
'groupby' => $groupby,
] = $this->get_participants_sql($additionalwhere, $additionalparams);
return $DB->get_recordset_sql("{$select} {$from} {$where} {$groupby} {$sort}", $params, $limitfrom, $limitnum);
$sql = "{$outerselect}
FROM ({$innerselect}
FROM {$innerjoins}
{$innerwhere}
) {$subqueryalias}
{$outerjoins}
{$outerwhere}
{$sort}";
return $DB->get_recordset_sql($sql, $params, $limitfrom, $limitnum);
}
/**
@ -116,12 +128,24 @@ class participants_search {
global $DB;
[
'from' => $from,
'where' => $where,
'subqueryalias' => $subqueryalias,
'innerselect' => $innerselect,
'outerjoins' => $outerjoins,
'innerjoins' => $innerjoins,
'outerwhere' => $outerwhere,
'innerwhere' => $innerwhere,
'params' => $params,
] = $this->get_participants_sql($additionalwhere, $additionalparams);
return $DB->count_records_sql("SELECT COUNT(DISTINCT(u.id)) {$from} {$where}", $params);
$sql = "SELECT COUNT(u.id)
FROM ({$innerselect}
FROM {$innerjoins}
{$innerwhere}
) {$subqueryalias}
{$outerjoins}
{$outerwhere}";
return $DB->count_records_sql($sql, $params);
}
/**
@ -137,6 +161,19 @@ class participants_search {
// Whether to match on users who HAVE accessed since the given time (ie false is 'inactive for more than x').
$matchaccesssince = false;
// The alias for the subquery that fetches all distinct course users.
$usersubqueryalias = 'targetusers';
// The alias for {user} within the distinct user subquery.
$inneruseralias = 'udistinct';
// Inner query that selects distinct users in a course who are not deleted.
// Note: This ensures the outer (filtering) query joins on distinct users, avoiding the need for GROUP BY.
$innerselect = "SELECT DISTINCT {$inneruseralias}.id";
$innerjoins = ["{user} {$inneruseralias}"];
$innerwhere = "WHERE {$inneruseralias}.deleted = 0";
$outerjoins = ["JOIN {user} u ON u.id = {$usersubqueryalias}.id"];
$wheres = [];
if ($this->filterset->has_filter('accesssince')) {
$accesssince = $this->filterset->get_filter('accesssince')->current();
@ -155,53 +192,46 @@ class participants_search {
'params' => $params,
] = $this->get_enrolled_sql();
$joins = ['FROM {user} u'];
$wheres = [];
// Set where statement(s) that must always be included (outside of filter wheres).
$forcedwhere = "u.deleted = 0";
$userfieldssql = user_picture::fields('u', $this->userfields);
// Include any compulsory enrolment SQL (eg capability related filtering that must be applied).
if (!empty($esqlforced)) {
$joins[] = "JOIN ({$esqlforced}) fef ON fef.id = u.id";
$outerjoins[] = "JOIN ({$esqlforced}) fef ON fef.id = u.id";
}
// Include any enrolment related filtering.
if (!empty($esql)) {
$joins[] = "LEFT JOIN ({$esql}) ef ON ef.id = u.id";
$outerjoins[] = "LEFT JOIN ({$esql}) ef ON ef.id = u.id";
$wheres[] = 'ef.id IS NOT NULL';
}
if ($isfrontpage) {
$select = "SELECT {$userfieldssql}, u.lastaccess";
$outerselect = "SELECT {$userfieldssql}, u.lastaccess";
if ($accesssince) {
$wheres[] = user_get_user_lastaccess_sql($accesssince, 'u', $matchaccesssince);
}
$groupby = ' GROUP BY u.id, u.lastaccess, ctx.id';
} else {
$select = "SELECT {$userfieldssql}, COALESCE(ul.timeaccess, 0) AS lastaccess";
$outerselect = "SELECT {$userfieldssql}, COALESCE(ul.timeaccess, 0) AS lastaccess";
// Not everybody has accessed the course yet.
$joins[] = 'LEFT JOIN {user_lastaccess} ul ON (ul.userid = u.id AND ul.courseid = :courseid2)';
$outerjoins[] = 'LEFT JOIN {user_lastaccess} ul ON (ul.userid = u.id AND ul.courseid = :courseid2)';
$params['courseid2'] = $this->course->id;
if ($accesssince) {
$wheres[] = user_get_course_lastaccess_sql($accesssince, 'ul', $matchaccesssince);
}
// Make sure we only ever fetch users in the course (regardless of enrolment filters).
$joins[] = 'JOIN {user_enrolments} ue ON ue.userid = u.id';
$joins[] = 'JOIN {enrol} e ON e.id = ue.enrolid
$innerjoins[] = "JOIN {user_enrolments} ue ON ue.userid = {$inneruseralias}.id";
$innerjoins[] = 'JOIN {enrol} e ON e.id = ue.enrolid
AND e.courseid = :courseid1';
$params['courseid1'] = $this->course->id;
$groupby = ' GROUP BY u.id, ul.timeaccess, ctx.id';
}
// Performance hacks - we preload user contexts together with accounts.
$ccselect = ', ' . context_helper::get_preload_record_columns_sql('ctx');
$ccjoin = 'LEFT JOIN {context} ctx ON (ctx.instanceid = u.id AND ctx.contextlevel = :contextlevel)';
$params['contextlevel'] = CONTEXT_USER;
$select .= $ccselect;
$joins[] = $ccjoin;
$outerselect .= $ccselect;
$outerjoins[] = $ccjoin;
// Apply any role filtering.
if ($this->filterset->has_filter('roles')) {
@ -242,35 +272,39 @@ class participants_search {
}
// Prepare final values.
$from = implode("\n", $joins);
$outerjoinsstring = implode("\n", $outerjoins);
$innerjoinsstring = implode("\n", $innerjoins);
if ($wheres) {
switch ($this->filterset->get_join_type()) {
case $this->filterset::JOINTYPE_ALL:
$firstjoin = ' AND ';
$wherenot = '';
$wheresjoin = ' AND ';
break;
case $this->filterset::JOINTYPE_NONE:
$firstjoin = ' AND NOT ';
$wherenot = ' NOT ';
$wheresjoin = ' AND NOT ';
break;
default:
// Default to 'Any' jointype.
$firstjoin = ' AND ';
$wherenot = '';
$wheresjoin = ' OR ';
break;
}
$where = "WHERE ({$forcedwhere}) {$firstjoin}" . implode($wheresjoin, $wheres);
$outerwhere = 'WHERE ' . $wherenot . implode($wheresjoin, $wheres);
} else {
$where = '';
$outerwhere = '';
}
return [
'select' => $select,
'from' => $from,
'where' => $where,
'subqueryalias' => $usersubqueryalias,
'outerselect' => $outerselect,
'innerselect' => $innerselect,
'outerjoins' => $outerjoinsstring,
'innerjoins' => $innerjoinsstring,
'outerwhere' => $outerwhere,
'innerwhere' => $innerwhere,
'params' => $params,
'groupby' => $groupby,
];
}