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Duolingo-style language learning database schema

How a gamified language app models its data: directional courses, a skill tree with unlock rules, lessons and exercise items, crown levels, a per-word spaced-repetition schedule, streaks with freezes, hearts and weekly leagues.

Duolingo Language ER diagram

Duolingo-style language learning database schema n1 n1 n1 n1 n1 n1 n1 n1 n1 n1 n1 n1 n1 n1 n1 n1 n1 n1 n1 users idBIGINT usernameVARCHAR emailVARCHAR display_nameVARCHAR ui_language_codeCHAR timezoneVARCHAR active_course_idBIGINT has_unlimited_hea…BOOLEAN created_atTIMESTAMPTZ languages idBIGINT codeVARCHAR name_enVARCHAR native_nameVARCHAR writing_directionVARCHAR has_diacriticsBOOLEAN courses idBIGINT from_language_idBIGINT to_language_idBIGINT slugVARCHAR statusVARCHAR skill_countINTEGER released_atDATE user_courses idBIGINT user_idBIGINT course_idBIGINT started_atTIMESTAMPTZ last_practised_onDATE total_xpINTEGER daily_goal_xpINTEGER placement_levelSMALLINT hearts_remainingSMALLINT hearts_refill_atTIMESTAMPTZ skills idBIGINT course_idBIGINT parent_skill_idBIGINT slugVARCHAR titleVARCHAR tree_ordinalINTEGER unlock_after_skil…BIGINT unlock_at_crown_l…SMALLINT max_crown_levelSMALLINT is_bonusBOOLEAN lessons idBIGINT skill_idBIGINT lesson_ordinalINTEGER min_crown_levelSMALLINT item_countSMALLINT xp_rewardINTEGER lexemes idBIGINT course_idBIGINT surface_formVARCHAR lemmaVARCHAR part_of_speechVARCHAR glossVARCHAR audio_urlVARCHAR difficulty_rankINTEGER exercise_items idBIGINT lesson_idBIGINT lexeme_idBIGINT exercise_typeVARCHAR promptTEXT accepted_answersJSONB distractorsJSONB audio_urlVARCHAR difficultySMALLINT user_skill_progress user_idBIGINT skill_idBIGINT crown_levelSMALLINT lessons_completed…SMALLINT is_unlockedBOOLEAN strength_percentSMALLINT last_practised_atTIMESTAMPTZ user_lexeme_reviews user_idBIGINT lexeme_idBIGINT first_learned_atTIMESTAMPTZ last_reviewed_atTIMESTAMPTZ due_atTIMESTAMPTZ half_life_hoursNUMERIC ease_factorNUMERIC repetitionsINTEGER lapsesINTEGER total_reviewsINTEGER is_retiredBOOLEAN daily_activity user_idBIGINT activity_dateDATE xp_earnedINTEGER lessons_completedSMALLINT goal_metBOOLEAN freeze_usedBOOLEAN streak_length_aft…INTEGER league_cohorts idBIGINT tierVARCHAR week_starts_onDATE week_ends_atTIMESTAMPTZ capacitySMALLINT promote_countSMALLINT demote_countSMALLINT is_settledBOOLEAN leaderboard_entries cohort_idBIGINT user_idBIGINT xp_this_weekINTEGER final_rankSMALLINT outcomeVARCHAR joined_atTIMESTAMPTZ

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