Add database schema migration

app/src/main/kotlin/xyz/etztech/stonks/App.kt

@@ -4,6 +4,7 @@ import com.natpryce.konfig.*
 import java.io.FileInputStream
 import java.util.*
 import kotlinx.coroutines.*
+import kotlinx.serialization.*
 import org.h2.tools.Server
 import org.jetbrains.exposed.exceptions.ExposedSQLException
 import org.jetbrains.exposed.sql.*
@@ -11,6 +12,7 @@ import org.jetbrains.exposed.sql.transactions.TransactionManager
 import org.jetbrains.exposed.sql.transactions.transaction
 import xyz.etztech.stonks.api.initApiServer
 import xyz.etztech.stonks.dsl.AggregateStatistics
+import xyz.etztech.stonks.dsl.KeyValue
 import xyz.etztech.stonks.dsl.LiveStatistics
 import xyz.etztech.stonks.dsl.Players
 import xyz.etztech.stonks.dsl.Statistics
@@ -91,6 +93,7 @@ fun initH2Server(
         SchemaUtils.create(LiveStatistics)
         SchemaUtils.create(AggregateStatistics)
         SchemaUtils.create(Players)
+        SchemaUtils.create(KeyValue)
 
         // Create indexes with explicit SQL because I can't figure out how to do it with exposed
         // Wrap it in a try block because it throws an exception if index already exists
@@ -113,6 +116,24 @@ fun initH2Server(
             TransactionManager.current()
                     .exec("CREATE INDEX idx_type_name ON LiveStatistics (\"Type\", \"Name\")")
         } catch (e: ExposedSQLException) {}
+
+        val schemaVersions =
+                KeyValue.slice(KeyValue.value).select { KeyValue.key.eq("SchemaVersion") }.map {
+                    it[KeyValue.value]
+                }
+        val schemaVersion = if (schemaVersions.count() > 0) schemaVersions.single() else 0
+        println("Database schemaVersion = ${schemaVersion}")
+
+        if (schemaVersion < 1) {
+            println("Migrating database to schemaVersion 1.")
+
+            TransactionManager.current().exec("TRUNCATE TABLE AGGREGATESTATISTICS")
+
+            KeyValue.insert {
+                it[KeyValue.key] = "SchemaVersion"
+                it[KeyValue.value] = 1
+            }
+        }
     }
 
     return database

app/src/main/kotlin/xyz/etztech/stonks/DSL.kt

@@ -41,3 +41,10 @@ object Players : Table() {
 
     override val primaryKey = PrimaryKey(id, name = "PK_id")
 }
+
+object KeyValue : Table() {
+    val key: Column<String> = varchar("Key", 150)
+    val value: Column<Int> = integer("Value")
+
+    override val primaryKey = PrimaryKey(key, name = "PK_key")
+}