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UTF-8 migration > Database conversion

This page is under construction!!

Only some preliminary ideas have been defined.

Differences between MySQL and PostgreSQL

Required 4.1! Detect how dabase/tables/columns have been created (charset...) How the set_names affect everything (from PHP to MySQL)

A big XML file will map all the required information to make the upgrade for global tables (like course, user etc)

Both modules and blocks will have their own XML file. (like those in /db *.sql) e.g.

<TABLE name="lesson_answers">
        <FIELD name="answer" method="PLAIN_SQL_UPDATE" type"text" length="0">
           SELECT l.course
           FROM {$CFG->prefix}lesson l,
                {$CFG->prefix}lesson_answers la
           WHERE = la.lessonid
                 AND = RECORDID
        <FIELD name="response" method="PLAIN_SQL_UPDATE" type"text" length="0">
           SELECT l.course
           FROM {$CFG->prefix}lesson l,
                {$CFG->prefix}lesson_answers la
           WHERE = la.lessonid
                 AND = RECORDID

The XML file will specify how to locate the course and the user every field belongs to, because translation will be done from course->lang or user->lang or site->lang to utf-8.

Those XML files will be read by one processor. This processor will pre-check that there is XML info available for each table in the DB. The processor will annotate the exact point it is, allowing to resume on crash!

It will be a two-stages process. 1st to convert all the texts, then to convert tables and column encodings (a possible alternative is to duplicate the entire DB with empty tables and then, move all contents to the new one) ?

It's highly possible that we need to increase DB requirements to MySQL 4.1 (great for the future!). Other users should stick at 1.5.

Collation support inside MySQL is great so we could specify different collations per lang and, dynamicaly sort query results differently.

As postgresql is quite different, an alternate DB migration must be performed for it.

Indexes could break under MySQL (because utf strings are 3x in size). Don't forget it!

create it able to run under different methods: - Under PHP application mode. - Processing items in chunks, saving the latest performed table and record to be able of resume in the exact point of break. - Able to be skipped for sites in only one encoding (making manual iconv to the database dump and importing again.

two stages, the conversion and the altering schema.

Check that the XML contains information for each $CFG->prefix table.

Try to convert table and column encoding following the XML too (reading metadata?)

Indexes to long. It's going to be a problem, sure!!

Modify all the DB creation scripts inside Moodle to specify encoding!!

All the fields in a table at the same time, record by record.

Deactivate the cron (creating a new $CFG->stopcron variable) and check that the site in under single-user mode (maintenance mode enabled).

List of tables and fields that need to be converted

(?) = in progress, not sure yet (x) = quite sure =P

Please let me know any table that I don't need to worry about.

adodb_logsql (?)

assignment (x) - name, description - course->lang = select c.lang from course c left join assignment a on = a.course where = - user->lang = -

assignment_submissions (x) - comment, data1, data2 - course->lang = select c.lang from course c left join assignement a on = a.course left join assignment_submissions as ass on = ass.assignment where = - user->lang = select u.lang from user u left join assignment_submissions as ass on = ass.userid where

backup_config (?)

backup_courses (x)

backup_files (x)

backup_ids (?)

backup_log (?)

block (x)

block_instance (?) -configdata (all empty?)

block_pinned (?) -configdata (?)

block_rss_client (?) -title, preferredtitle, description(?)

cache_filters (?)

cache_text (?)

chat (x) -name, intro

chat_messages (x) -message

chat_users (x)

choice (x) -name, text

choice_answers (x)

choice_options (x) -text

config (x) -value see hokudai page 2 in db, chars embedded in tags

config_plugins (?)

course (x) password(raw string, see koniv database), fullname, shortname, idnumber, summary, teacher, teachers, student, students

course_allowed_modules (x)

course_categories (x) -name, description

course_display (x)

course_meta (x)

course_modules (x)

course_request (?)

course_sections (x) -summary

data (x) -name, intro

data_comments (x)

data_content (x) -conent(composite)

data_fields (x) -name, description

data_ratings (x)

data_records (x)

dialogue (x) -name, intro

dialogue_conversations (x) -subject

dialogue_entries (x) -text;

downloads (?)

enrol_authorize (?)

enrol_paypal (?)

event (x) -name(composite!), description

exercise (x) -name, md5(password?)

exercise_assessments (x) -generalcomment, teachercomment

exercise_elements (x) -description

exercise_grades (x) -feedback

exercise_rubrics (x) -description

exercise_submissions (x) -title

forum (x) -name, intro

forum_discussions (x) -name

forum_posts (x) -subject, message, attachment (stripeed &#, no need to convert?)

forum_queue (x)

forum_ratings (x)

forum_read (x)

forum_subscriptions (x)

forum_track_prefs (x)

glossary (x) -name, intro

glossary_alias (x) -alias

glossary_categories (x) -name

glossary_comments (x) -comment

glossary_entries (x) -concept, definition

glossary_entries_categories (x)

glossary_formats (x)

glossary_ratings (x)

grade_category (x) -name

grade_exceptions (x)

grade_item (x)

grade_letter (x) -letter

grade_preferences (x)

groups -name, description, password(stripped), theme(?)

groups_members (x)

hotpot(x) -name, summary

hotpot_attempts (x)

hotpot_details (x) -details

hotpot_questions (x) -name

hotpot_responses (?)

hotpot_strings (x) -string

journal (x) -name, intro

journal_entries (x) -comment, text

label (x) name, content (with html)

lams (???)

lesson (x) -name, password is (md5(NCR))?

lesson_answers (x) -answer, response

lesson_attempts (?) -useranswer(?)

lesson_branch (x)

lesson_default (x) -password(md5(NCR))?

lesson_grades (x)


lesson_pages (x) -title, content

lesson_timer (x)

log (x) -info (hokai as well)

log_display (x)

message (x) -message (not NCR!)

message_contacts (x)

message_read (x) -message (not NCR!)

modules (x)

quiz (x) -name, intro, password(md5)?

quiz_answers (x) -answer, feedback

quiz_attemptonlast_datasets (x)

quiz_attempts (x)

quiz_calculated (x)

quiz_categories (x) -name, info

quiz_dataset_definitions (?)

quiz_dataset_items (?)

quiz_essay (x)

quiz_essay_states (??)

quiz_grades (x)

quiz_match (x)

quiz_match_sub (x) -questiontext, answertext

quiz_multianswers (x)

quiz_multichoice (x)

quiz_newest_states (x)

quiz_numerical (x)

quiz_numerical_units (x) -unit

quiz_question_datasets (x)

quiz_question_instances (x)

quiz_question_versions (x)

quiz_questions (x) -name, questiontext

quiz_randomsamatch (x)

quiz_rqp (?)

quiz_rqp_servers (?)

quiz_rqp_states (?)

quiz_rqp_types (?)

quiz_shortanswer (x)

quiz_states (x) answer - composite!

quiz_truefalse (x)

registry (x) -sitename, adminname

registry_votes (?)

resource (x) -name, summary, alltext

scale (x) -name, description, scale

scorm (?) -name, summary

scorm_scoes (?)

scorm_scoes_track (?)

sessions (?)

stats_daily (x)

stats_monthly (x)

stats_user_daily (?) -stattype

stats_user_monthly (x)

stats_user_weekly (x)


survey (x) -name, intro

survey_analysis (x) -notes

survey_answers (?) -answerone, answertwo??

survey_questions (?)


user (x) -firstname, lastname, department, institution, address, city, description, secret(?)

user_admins (x)

user_coursecreators (x)

user_preferences (x)

user_students (x)

user_teachers (x)

wiki (x) -name, summary, pagename, initialcontent

wiki_entries (x) -pagename

wiki_pages (x) -pagename, content, author, ref

workshop (x) -name, description

workshop_assessments (x) -generalcomment, teachercomment

workshop_comments (x) -comments

workshop_elements (x) -description

workshop_grades (x) -feedback

workshop_rubrics (x) -description

workshop_stockcomments (x) -comments

workshop_submissions (x) -title