Slow Query: querying gameRatingsSandbox0 does a full scan of `reviews` table

[dfabulich]

Here's an example slow query from the "Authored Games" section of the user profile page. As I read it, it's doing a full scan of the entire reviews table.

See also #401

# User@Host: ifdb[ifdb] @ localhost [127.0.0.1]
# Thread_id: 6588583  Schema: ifdb  QC_hit: No
# Query_time: 19.694899  Lock_time: 0.000966  Rows_sent: 1  Rows_examined: 215063
# Rows_affected: 0  Bytes_sent: 1195
# Tmp_tables: 5  Tmp_disk_tables: 1  Tmp_table_sizes: 7012300
# Full_scan: Yes  Full_join: No  Tmp_table: Yes  Tmp_table_on_disk: Yes
# Filesort: Yes  Filesort_on_disk: No  Merge_passes: 1  Priority_queue: No
#
# explain: id   select_type table   type    possible_keys   key key_len ref rows    r_rows  filtered    r_filtered  Extra
# explain: 1    PRIMARY gameprofilelinks    ref gameid,userid   userid  34  const   1   1.00    100.00  100.00  Using index condition; Using temporary; Using filesort
# explain: 1    PRIMARY games   eq_ref  PRIMARY PRIMARY 34  ifdb.gameprofilelinks.gameid    1   1.00    100.00  100.00  
# explain: 1    PRIMARY <derived4>  ref key0    key0    34  ifdb.gameprofilelinks.gameid    10  1.00    100.00  100.00  
# explain: 4    DERIVED <derived5>  ALL NULL    NULL    NULL    NULL    68110   22599.00    100.00  100.00  Using temporary; Using filesort
# explain: 5    DERIVED reviews ALL NULL    NULL    NULL    NULL    68110   68110.00    100.00  93.12   Using where; Using temporary; Using filesort
# explain: 5    DERIVED users   eq_ref  PRIMARY PRIMARY 34  ifdb.reviews.userid 1   1.00    100.00  100.00  Using where
#
SET timestamp=1696913654;
select
           games.id as id, games.title as title, games.author as author,
           date_format(games.published, '%Y') as year,
           games.`desc` as `desc`,
           (coverart is not null) as hasart,
           grv.avgRating as rating,
           grv.numRatingsInAvg as ratingCnt,
           flags
         from
           games
           join gameprofilelinks
             on games.id = gameprofilelinks.gameid
           left outer join gameRatingsSandbox0 as grv
             on grv.gameid = games.id
         where
           gameprofilelinks.userid = 'wr91n7k4p0ohlxb'
         group by games.id
         order by starsort desc;