H2 schema disappears after connection is closed - sql

Question

after setting up a schema in an H2 database for unit testing, the unit tests relying on the schema could not find it.
import java.sql.DriverManager
Class.forName("org.h2.Driver")
val setupConn = DriverManager.getConnection("jdbc:h2:mem:test_data_metrics;MODE=PostgreSQL", "sa", "")
val setupStmt = setupConn.createStatement
// setup schema at the beginning of our test
setupStmt.execute("CREATE SCHEMA IF NOT EXISTS my_test_schema AUTHORIZATION sa;")
setupStmt.execute("GRANT ALL ON SCHEMA my_test_schema TO sa;")
setupStmt.execute("CREATE TABLE IF NOT EXISTS my_test_schema.my_test_table (test_id VARCHAR(255), test_column VARCHAR(255));")
setupStmt.executeQuery("select * from my_test_schema.my_test_table")
// res4: java.sql.ResultSet = rs3: org.h2.result.LocalResultImpl#3eb10d62 columns: 2 rows: 0 pos: -1
// this seems to work correctly ^^^
setupStmt.close
setupConn.close
// now run our test using the schema we just set up
val conn = DriverManager.getConnection("jdbc:h2:mem:test_data_metrics;SCHEMA=my_test_schema;MODE=PostgreSQL", "sa", "")
val stmt = conn.createStatement
stmt.executeQuery("select * from my_test_table where test_id = '1'")
// org.h2.jdbc.JdbcSQLSyntaxErrorException: Schema "MY_TEST_SCHEMA" not found; SQL statement:
// SET SCHEMA my_test_schema [90079-200]
// ^^^^ something has gone horribly wrong

Answer 1

You can simply add ;DB_CLOSE_DELAY=-1 to the JDBC URL; no need to have an active connection.
https://h2database.com/html/commands.html#set_db_close_delay
If you use a some recent version of H2, you may also want to add ;DATABASE_TO_LOWER=TRUE for better compatibility with PostgreSQL; the PostgreSQL compatibility mode by itself doesn't imply this setting.

Answer 2

This is embarrassing, but I didn't realize that when I closed the connection to my in memory database, the database would dry up and blow away. This seems obvious in retrospect. The solution is to keep the first connection to the database open throughout testing.
import java.sql.DriverManager
Class.forName("org.h2.Driver")
val setupConn = DriverManager.getConnection("jdbc:h2:mem:test_data_metrics;MODE=PostgreSQL", "sa", "")
val setupStmt = setupConn.createStatement
// setup schema at the beginning of our test
setupStmt.execute("CREATE SCHEMA IF NOT EXISTS my_test_schema AUTHORIZATION sa;")
setupStmt.execute("GRANT ALL ON SCHEMA my_test_schema TO sa;")
setupStmt.execute("CREATE TABLE IF NOT EXISTS my_test_schema.my_test_table (test_id VARCHAR(255), test_column VARCHAR(255));")
setupStmt.executeQuery("select * from my_test_schema.my_test_table")
// res4: java.sql.ResultSet = rs3: org.h2.result.LocalResultImpl#3eb10d62 columns: 2 rows: 0 pos: -1
// DON'T CLOSE THE CONNECTION YET!
//setupStmt.close
//setupConn.close
val conn = DriverManager.getConnection("jdbc:h2:mem:test_data_metrics;SCHEMA=my_test_schema;MODE=PostgreSQL", "sa", "")
val stmt = conn.createStatement
stmt.executeQuery("select * from my_test_table where test_id = '1'")
// res5: java.sql.ResultSet = rs4: org.h2.result.LocalResultImpl#293e66e4 columns: 2 rows: 0 pos: -1
// ^^^^ huzzah!