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Dropping one UNIQUE index over NULLable columns. It isn't

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cross-db at all. So we make the composite index not unique
to get speed benefits but the unique constraint is
controlled programatically.
This commit is contained in:
stronk7 2007-09-06 18:31:13 +00:00
parent 77d574a8c5
commit 4a039315d7
2 changed files with 34 additions and 4 deletions
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9
lib/db/install.xml
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@ -1,5 +1,5 @@
<?xml version="1.0" encoding="UTF-8" ?>
<XMLDB PATH="lib/db" VERSION="20070905" COMMENT="XMLDB file for core Moodle tables"
<XMLDB PATH="lib/db" VERSION="20070906" COMMENT="XMLDB file for core Moodle tables"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="../../lib/xmldb/xmldb.xsd"
>
@ -156,8 +156,8 @@
<INDEX NAME="visible" UNIQUE="false" FIELDS="visible" NEXT="course"/>
<INDEX NAME="course" UNIQUE="false" FIELDS="course" PREVIOUS="visible" NEXT="module"/>
<INDEX NAME="module" UNIQUE="false" FIELDS="module" PREVIOUS="course" NEXT="instance"/>
<INDEX NAME="instance" UNIQUE="false" FIELDS="instance" PREVIOUS="module" NEXT="idnumber"/>
<INDEX NAME="idnumber" UNIQUE="true" FIELDS="idnumber" COMMENT="Default comment for the index, please edit me" PREVIOUS="instance"/>
<INDEX NAME="instance" UNIQUE="false" FIELDS="instance" PREVIOUS="module" NEXT="idnumber-course"/>
<INDEX NAME="idnumber-course" UNIQUE="false" FIELDS="idnumber, course" COMMENT="non unique index (although programatically we are guarantying some sort of uniqueness both under this table and the grade_items one). TODO: We need a central store of module idnumbers in the future." PREVIOUS="instance"/>
</INDEXES>
</TABLE>
<TABLE NAME="course_sections" COMMENT="to define the sections for each course" PREVIOUS="course_modules" NEXT="course_request">
@ -1344,7 +1344,8 @@
<INDEXES>
<INDEX NAME="locked-locktime" UNIQUE="false" FIELDS="locked, locktime" COMMENT="used in grading cron" NEXT="itemtype-needsupdate"/>
<INDEX NAME="itemtype-needsupdate" UNIQUE="false" FIELDS="itemtype, needsupdate" COMMENT="used in grading cron" PREVIOUS="locked-locktime" NEXT="gradetype"/>
<INDEX NAME="gradetype" UNIQUE="false" FIELDS="gradetype" COMMENT="index for gradetype" PREVIOUS="itemtype-needsupdate"/>
<INDEX NAME="gradetype" UNIQUE="false" FIELDS="gradetype" COMMENT="index for gradetype" PREVIOUS="itemtype-needsupdate" NEXT="idnumber-courseid"/>
<INDEX NAME="idnumber-courseid" UNIQUE="false" FIELDS="idnumber, courseid" COMMENT="non unique index (although programatically we are guarantying some sort of uniqueness both under this table and the course_modules one). TODO: We need a central store of module idnumbers in the future." PREVIOUS="gradetype"/>
</INDEXES>
</TABLE>
<TABLE NAME="grade_grades" COMMENT="grade_grades This table keeps individual grades for each user and each item, exactly as imported or submitted by modules. The rawgrademax/min and rawscaleid are stored here to record the values at the time the grade was stored, because teachers might change this for an activity! All the results are normalised/resampled for the final grade value." PREVIOUS="grade_items" NEXT="grade_grades_text">

29
lib/db/upgrade.php
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@ -2034,6 +2034,35 @@ function xmldb_main_upgrade($oldversion=0) {
}
}
/// To have UNIQUE indexes over NULLable columns isn't cross-db at all
/// so we create a non unique index and programatically enforce uniqueness
if ($result && $oldversion < 2007090600) {
/// Define index idnumber (unique) to be dropped form course_modules
$table = new XMLDBTable('course_modules');
$index = new XMLDBIndex('idnumber');
$index->setAttributes(XMLDB_INDEX_UNIQUE, array('idnumber'));
/// Launch drop index idnumber
$result = $result && drop_index($table, $index);
/// Define index idnumber-course (not unique) to be added to course_modules
$table = new XMLDBTable('course_modules');
$index = new XMLDBIndex('idnumber-course');
$index->setAttributes(XMLDB_INDEX_NOTUNIQUE, array('idnumber', 'course'));
/// Launch add index idnumber-course
$result = $result && add_index($table, $index);
/// Define index idnumber-courseid (not unique) to be added to grade_items
$table = new XMLDBTable('grade_items');
$index = new XMLDBIndex('idnumber-courseid');
$index->setAttributes(XMLDB_INDEX_NOTUNIQUE, array('idnumber', 'courseid'));
/// Launch add index idnumber-courseid
$result = $result && add_index($table, $index);
}
/*