exposed-imdb/README.md

Exposed Imdb

A simple project to learn more about exposed, using the imdb datasets.

Please note that if you use this project, you have to comply with the Imbd license.

LICENSE

In short, CC BY-NC-SA 4.0.

See LICENSE

Learnings

• Use ;DB_CLOSE_DELAY=-1 if you want to persist the in-memory database information over more than a single transaction.
  • Database.connect("jdbc:h2:mem:test;DB_CLOSE_DELAY=-1", driver = "org.h2.Driver", user = "root", password = "")
• Use ?useSSL=false to avoid SSL exceptions (for dev only!) on MySQL.
  • Database.connect("jdbc:mysql://localhost:3308/imdb?useSSL=false", driver = "com.mysql.jdbc.Driver", user = "root", password = "aRootPassword")
• Use rewriteBatchedStatements=true when inserting large volumes of data to have your driver rewrite your query
• .map keeps stack of memory while for loop doesn't? I get a OME when running with map
• reason to use partitions
• dsl loading copy paste prone
• Cross Join
• references

1
[dsl.Titles.primaryTitle=The Lego Batman Movie, dsl.Titles.titleType=movie, dsl.Ratings.averageRating=7.3, dsl.Ratings.numVotes=123790]
dsl.Titles.primaryTitle=The Lego Batman Movie, dsl.Titles.titleType=movie, dsl.Ratings.averageRating=7.3, dsl.Ratings.numVotes=123790
Ratings query took : 3170
1
[dsl.Titles.primaryTitle=The Lego Batman Movie, dsl.Titles.titleType=movie, dsl.Ratings.averageRating=7.3, dsl.Ratings.numVotes=123790]
dsl.Titles.primaryTitle=The Lego Batman Movie, dsl.Titles.titleType=movie, dsl.Ratings.averageRating=7.3, dsl.Ratings.numVotes=123790
Ratings query took : 2159

object Titles : IntIdTable() {
    val tconst: Column<String> = (varchar("tconst", 10) references Ratings.tconst).uniqueIndex()
    val titleType: Column<String> = varchar("titleType", 50) // TODO: Own Table?
    val primaryTitle: Column<String> = varchar("primaryTitle", 500)
    val originalTitle: Column<String> = varchar("originalTitle", 500)
    val isAdult: Column<Boolean> = bool("isAdult")
    val startYear: Column<Int?> = integer("startYear").nullable()
    val endYear: Column<Int?> = integer("endYear").nullable()
    val runtimeMinutes: Column<Long?> = long("runtimeMinutes").nullable()
    val genres: Column<String> = varchar("genres", 50) // TODO: Own Table?
}

object Ratings : IntIdTable(){
    val tconst : Column<String> = varchar("tconst", 10).uniqueIndex()
    val averageRating : Column<Float?> = float("averageRating").nullable()
    val numVotes : Column<Int?> = integer("numVotes").nullable()
}

    println("Ratings query took : ${measureTimeMillis() {
        transaction(db) {
            var result = (Titles innerJoin Ratings).slice(Titles.primaryTitle, Titles.titleType, Ratings.averageRating, Ratings.numVotes).select {
                ((Titles.primaryTitle like "The Lego Batman Movie") and (Titles.titleType like "movie")
                        and Titles.tconst.eq(Ratings.tconst))
            }.toList()

            println(result.size)
            println(result)
            println(result.first())
        }
    }}");

Author

• Julien Lengrand-Lambert