In-memory Sqlite DB disappears between transactions

I have an in-memory sqlite db. The following code yields an error. Here’s the code:

import org.jetbrains.exposed.dao.EntityID
import org.jetbrains.exposed.dao.UUIDEntity
import org.jetbrains.exposed.dao.UUIDEntityClass
import org.jetbrains.exposed.dao.UUIDTable
import org.jetbrains.exposed.sql.*
import org.jetbrains.exposed.sql.transactions.TransactionManager
import org.jetbrains.exposed.sql.transactions.transaction
import photo.backup.kt.data.HashTable
import java.sql.Connection
import java.util.*

object MyTable: UUIDTable() {
    val name = varchar("name", 50)
}

class Name(id: EntityID<UUID>): UUIDEntity(id) {
    companion object: UUIDEntityClass<Name>(MyTable)

    var name by MyTable.name
}

fun main() {
    val db = Database.connect("jdbc:sqlite:file:test?mode=memory&cache=shared", "org.sqlite.JDBC")
    TransactionManager.manager.defaultIsolationLevel = Connection.TRANSACTION_SERIALIZABLE
    transaction(db) {
        addLogger(StdOutSqlLogger)
        SchemaUtils.create(MyTable)
    }
    println(UUID.randomUUID())
    val id = transaction(db) {
        MyTable.insert {
            it[name] = "Foo"
        } get MyTable.id
    }
    println(id)
}

main()

Here’s the error:

Exception in thread "main" org.jetbrains.exposed.exceptions.ExposedSQLException: org.sqlite.SQLiteException: [SQLITE_ERROR] SQL error or missing database (no such table: My)
SQL: [INSERT INTO My (id, "name") VALUES (?, ?)]
	at org.jetbrains.exposed.sql.statements.Statement.executeIn$exposed_core(Statement.kt:50)
	at org.jetbrains.exposed.sql.Transaction.exec(Transaction.kt:122)
	at org.jetbrains.exposed.sql.Transaction.exec(Transaction.kt:108)
	at org.jetbrains.exposed.sql.statements.Statement.execute(Statement.kt:29)
	at org.jetbrains.exposed.sql.QueriesKt.insert(Queries.kt:45)
	at org.jetbrains.kotlin.idea.scratch.generated.ScratchFileRunnerGenerated$ScratchFileRunnerGenerated$main$id$1.invoke(tmp.kt:34)
	at org.jetbrains.kotlin.idea.scratch.generated.ScratchFileRunnerGenerated$ScratchFileRunnerGenerated$main$id$1.invoke(tmp.kt:16)
	at org.jetbrains.exposed.sql.transactions.ThreadLocalTransactionManagerKt$inTopLevelTransaction$1.invoke(ThreadLocalTransactionManager.kt:156)
	at org.jetbrains.exposed.sql.transactions.ThreadLocalTransactionManagerKt$inTopLevelTransaction$2.invoke(ThreadLocalTransactionManager.kt:197)
	at org.jetbrains.exposed.sql.transactions.ThreadLocalTransactionManagerKt.keepAndRestoreTransactionRefAfterRun(ThreadLocalTransactionManager.kt:205)
	at org.jetbrains.exposed.sql.transactions.ThreadLocalTransactionManagerKt.inTopLevelTransaction(ThreadLocalTransactionManager.kt:196)
	at org.jetbrains.exposed.sql.transactions.ThreadLocalTransactionManagerKt$transaction$1.invoke(ThreadLocalTransactionManager.kt:134)
	at org.jetbrains.exposed.sql.transactions.ThreadLocalTransactionManagerKt.keepAndRestoreTransactionRefAfterRun(ThreadLocalTransactionManager.kt:205)
	at org.jetbrains.exposed.sql.transactions.ThreadLocalTransactionManagerKt.transaction(ThreadLocalTransactionManager.kt:106)
	at org.jetbrains.exposed.sql.transactions.ThreadLocalTransactionManagerKt.transaction(ThreadLocalTransactionManager.kt:104)
	at org.jetbrains.kotlin.idea.scratch.generated.ScratchFileRunnerGenerated$ScratchFileRunnerGenerated.main(tmp.kt:33)
	at org.jetbrains.kotlin.idea.scratch.generated.ScratchFileRunnerGenerated$ScratchFileRunnerGenerated.generated_get_instance_res0(tmp.kt:40)
	at org.jetbrains.kotlin.idea.scratch.generated.ScratchFileRunnerGenerated.main(tmp.kt:52)
Caused by: org.sqlite.SQLiteException: [SQLITE_ERROR] SQL error or missing database (no such table: My)
	at org.sqlite.core.DB.newSQLException(DB.java:909)
	at org.sqlite.core.DB.newSQLException(DB.java:921)
	at org.sqlite.core.DB.throwex(DB.java:886)
	at org.sqlite.core.NativeDB.prepare_utf8(Native Method)
	at org.sqlite.core.NativeDB.prepare(NativeDB.java:127)
	at org.sqlite.core.DB.prepare(DB.java:227)
	at org.sqlite.core.CorePreparedStatement.<init>(CorePreparedStatement.java:41)

chaging Database.connect("jdbc:sqlite:file:test?mode=memory&cache=shared", "org.sqlite.JDBC") to Database.connect("jdbc:sqlite:/path/to/data.db", "org.sqlite.JDBC")

then the DB is created and the insertion happens correctly

[kylegoetz]

Connection pooling with Hikari works. It might be useful to put a note about this in an example for Sqlite in-memory DBs since the docs don’t make it clear that a Sqlite in-memory DB will be destroyed between transactions. Here is sample code for using Hikari connection pooling with a Sqlite in-memory DB:

val cfg: HikariConfig = HikariConfig().apply {
    jdbcUrl = "dbc:sqlite::memory:"
    maximumPoolSize = 6
}
val dataSource = HikariDataSource(cfg)
val database = Database.connect(dataSource)

Now the in-memory DB will not be destroyed between transactions.

[trathschlag]

I used the following workaround:

val sqlitePath = "jdbc:sqlite:file:test?mode=memory&cache=shared"
val keepAliveConnection = DriverManager.getConnection(sqlitePath)
val db = Database.connect(sqlitePath)

As long as you don’t close() the keepAliveConnection, the Database will persist in memory. Not pretty, but works.