From 02fe9314e42b604bf58849916652e81ffefd5781 Mon Sep 17 00:00:00 2001
From: caadiq <caadiq@gmail.com>
Date: Tue, 13 Jan 2026 22:41:15 +0900
Subject: [PATCH] =?UTF-8?q?fix(suggestions):=20=EB=8F=99=EC=A0=81=20?=
 =?UTF-8?q?=EC=9E=84=EA=B3=84=EA=B0=92=EC=9C=BC=EB=A1=9C=20=EC=B6=94?=
 =?UTF-8?q?=EC=B2=9C=20=EA=B2=80=EC=83=89=EC=96=B4=20=ED=95=84=ED=84=B0?=
 =?UTF-8?q?=EB=A7=81?=
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- 최대 검색 횟수의 1% 또는 최소 10회 중 더 큰 값 적용
- GREATEST(MAX(count) * 0.01, 10) 사용
- 데이터가 적을 때도 오타 필터링 가능

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
---
 backend/services/suggestions.js | 63 ++++++++++++++-------------------
 1 file changed, 27 insertions(+), 36 deletions(-)

diff --git a/backend/services/suggestions.js b/backend/services/suggestions.js
index ba53c96..258eeed 100644
--- a/backend/services/suggestions.js
+++ b/backend/services/suggestions.js
@@ -9,6 +9,12 @@ const inko = new Inko();
 const SUGGESTION_PREFIX = "suggestions:";
 const CACHE_TTL = 86400; // 24시간
 
+// 추천 검색어로 노출되기 위한 최소 비율 (최대 검색 횟수 대비)
+// 예: 0.01 = 최대 검색 횟수의 1% 이상만 노출
+const MIN_COUNT_RATIO = 0.01;
+// 최소 임계값 (데이터가 적을 때 오타 방지)
+const MIN_COUNT_FLOOR = 10;
+
 /**
  * 영문만 포함된 검색어인지 확인
  */
@@ -166,38 +172,21 @@ export async function getSuggestions(query, limit = 10) {
 
 /**
  * 다음 단어 예측 (Bi-gram 기반)
+ * 동적 임계값을 사용하므로 Redis 캐시를 사용하지 않음
  */
 async function getNextWordSuggestions(lastWord, prefix, limit) {
   try {
-    // 1. Redis 캐시 확인
-    const cacheKey = `${SUGGESTION_PREFIX}${lastWord}`;
-    let nextWords = await redis.zrevrange(cacheKey, 0, limit - 1);
+    const [rows] = await pool.query(
+      `SELECT word2, count FROM word_pairs
+               WHERE word1 = ?
+                 AND count >= GREATEST((SELECT MAX(count) * ? FROM word_pairs), ?)
+               ORDER BY count DESC
+               LIMIT ?`,
+      [lastWord, MIN_COUNT_RATIO, MIN_COUNT_FLOOR, limit]
+    );
 
-    // 2. 캐시 미스 시 DB 조회 후 Redis 채우기
-    if (nextWords.length === 0) {
-      const [rows] = await pool.query(
-        `SELECT word2, count FROM word_pairs 
-                 WHERE word1 = ? 
-                 ORDER BY count DESC 
-                 LIMIT ?`,
-        [lastWord, limit * 2] // 여유있게 가져오기
-      );
-
-      if (rows.length > 0) {
-        // Redis에 캐싱
-        const multi = redis.multi();
-        for (const row of rows) {
-          multi.zadd(cacheKey, row.count, row.word2);
-        }
-        multi.expire(cacheKey, CACHE_TTL);
-        await multi.exec();
-
-        nextWords = rows.map((r) => r.word2);
-      }
-    }
-
-    // 3. prefix + 다음 단어 조합으로 반환
-    return nextWords.slice(0, limit).map((word) => `${prefix} ${word}`);
+    // prefix + 다음 단어 조합으로 반환
+    return rows.map((r) => `${prefix} ${r.word2}`);
   } catch (error) {
     console.error("[SearchSuggestion] Bi-gram 조회 오류:", error.message);
     return [];
@@ -217,20 +206,22 @@ async function getPrefixSuggestions(prefix, koreanPrefix, limit) {
     if (koreanPrefix) {
       // 영어 원본과 한글 변환 둘 다 검색
       [rows] = await pool.query(
-        `SELECT query FROM search_queries 
-             WHERE query LIKE ? OR query LIKE ?
-             ORDER BY count DESC, last_searched_at DESC 
+        `SELECT query FROM search_queries
+             WHERE (query LIKE ? OR query LIKE ?)
+               AND count >= GREATEST((SELECT MAX(count) * ? FROM search_queries), ?)
+             ORDER BY count DESC, last_searched_at DESC
              LIMIT ?`,
-        [`${prefix}%`, `${koreanPrefix}%`, limit]
+        [`${prefix}%`, `${koreanPrefix}%`, MIN_COUNT_RATIO, MIN_COUNT_FLOOR, limit]
       );
     } else {
       // 단일 검색
       [rows] = await pool.query(
-        `SELECT query FROM search_queries 
-             WHERE query LIKE ? 
-             ORDER BY count DESC, last_searched_at DESC 
+        `SELECT query FROM search_queries
+             WHERE query LIKE ?
+               AND count >= GREATEST((SELECT MAX(count) * ? FROM search_queries), ?)
+             ORDER BY count DESC, last_searched_at DESC
              LIMIT ?`,
-        [`${prefix}%`, limit]
+        [`${prefix}%`, MIN_COUNT_RATIO, MIN_COUNT_FLOOR, limit]
       );
     }