Optimize the test-DB creation process:

- Use views of the "initialDatabase" view and tables to a) reduce the amount of space used by test-DBs and b) improve test-db creation performance.
- Avoid possible failures from outdated metadata.

src/main/java/eu/openaire/urls_controller/configuration/DatabaseConnector.java

@@ -58,23 +58,29 @@ public class DatabaseConnector {
             logger.info("Going to create (if not exist) the TEST-database \"" + testDatabaseName + "\" and its tables. Also will fill some tables with data from the initial-database \"" + initialDatabaseName + "\".");
             jdbcTemplate.execute("CREATE DATABASE IF NOT EXISTS " + testDatabaseName);
 
-            jdbcTemplate.execute("CREATE TABLE IF NOT EXISTS " + testDatabaseName + ".publication stored as parquet as select * from " + initialDatabaseName + ".publication");
-            jdbcTemplate.execute("COMPUTE STATS " + testDatabaseName + ".publication");
+            try {   // Metastore takes some time to recognize the DB has been created, in order to use it later..
+                Thread.sleep(1000);
+            } catch (InterruptedException ignore) {}
 
-            jdbcTemplate.execute("CREATE TABLE IF NOT EXISTS " + testDatabaseName + ".publication_pids stored as parquet as select * from " + initialDatabaseName + ".publication_pids");
-            jdbcTemplate.execute("COMPUTE STATS " + testDatabaseName + ".publication_pids");
+            jdbcTemplate.update("INVALIDATE METADATA");
 
-            jdbcTemplate.execute("CREATE TABLE IF NOT EXISTS " + testDatabaseName + ".publication_urls stored as parquet as select * from " + initialDatabaseName + ".publication_urls");
-            jdbcTemplate.execute("COMPUTE STATS " + testDatabaseName + ".publication_urls");
+            try {   // Metastore takes some time to recognize the DB has been created, in order to use it later..
+                Thread.sleep(1000);
+            } catch (InterruptedException ignore) {}
 
-            jdbcTemplate.execute("CREATE TABLE IF NOT EXISTS " + testDatabaseName + ".publication_boost stored as parquet as select * from " + initialDatabaseName + ".publication_boost");
-            jdbcTemplate.execute("COMPUTE STATS " + testDatabaseName + ".publication_boost");
+            // Create VIEWs of the original data. We just READ from it, so it's safe for our testing environment..
 
-            jdbcTemplate.execute("CREATE TABLE IF NOT EXISTS " + testDatabaseName + ".datasource stored as parquet as select * from " + initialDatabaseName + ".datasource");
-            jdbcTemplate.execute("COMPUTE STATS " + testDatabaseName + ".datasource");
+            jdbcTemplate.execute("CREATE VIEW IF NOT EXISTS " + testDatabaseName + ".publication as select * from " + initialDatabaseName + ".publication");
 
-            jdbcTemplate.execute("CREATE TABLE IF NOT EXISTS " + testDatabaseName + ".payload_legacy stored as parquet as select * from " + initialDatabaseName + ".payload_legacy");
-            jdbcTemplate.execute("COMPUTE STATS " + testDatabaseName + ".payload_legacy");
+            jdbcTemplate.execute("CREATE VIEW IF NOT EXISTS " + testDatabaseName + ".publication_pids as select * from " + initialDatabaseName + ".publication_pids");
+
+            jdbcTemplate.execute("CREATE VIEW IF NOT EXISTS " + testDatabaseName + ".publication_urls as select * from " + initialDatabaseName + ".publication_urls");
+
+            jdbcTemplate.execute("CREATE VIEW IF NOT EXISTS " + testDatabaseName + ".publication_boost as select * from " + initialDatabaseName + ".publication_boost");
+
+            jdbcTemplate.execute("CREATE VIEW IF NOT EXISTS " + testDatabaseName + ".datasource as select * from " + initialDatabaseName + ".datasource");
+
+            jdbcTemplate.execute("CREATE VIEW IF NOT EXISTS " + testDatabaseName + ".payload_legacy as select * from " + initialDatabaseName + ".payload_legacy");
 
             databaseName = testDatabaseName;
         } else {
@@ -107,9 +113,21 @@ public class DatabaseConnector {
         jdbcTemplate.execute("CREATE TABLE IF NOT EXISTS " + databaseName + ".payload_bulk_import (id string, original_url string, actual_url string, `date` bigint, mimetype string, size string, `hash` string, `location` string, provenance string) stored as parquet");
         jdbcTemplate.execute("COMPUTE STATS " + databaseName + ".payload_bulk_import");
 
-        jdbcTemplate.execute("CREATE VIEW IF NOT EXISTS " + databaseName + ".payload " +
-                                                        "AS SELECT * from " + databaseName + ".payload_legacy " +
-                                                        "UNION ALL SELECT * FROM " + databaseName +".payload_aggregated " +
+
+        try {   // Metastore takes some time to recognize the tables have been created, in order to use them in the view.
+            Thread.sleep(1000);
+        } catch (InterruptedException ignore) {}
+
+        jdbcTemplate.update("INVALIDATE METADATA");
+
+        try {   // Metastore takes some time to recognize the tables have been created, in order to use them in the view.
+            Thread.sleep(1000);
+        } catch (InterruptedException ignore) {}
+
+
+        jdbcTemplate.execute("CREATE VIEW IF NOT EXISTS " + databaseName + ".payload\n" +
+                                                        "AS SELECT * from " + databaseName + ".payload_legacy\n" +
+                                                        "UNION ALL SELECT * FROM " + databaseName +".payload_aggregated\n" +
                                                         "UNION ALL SELECT * FROM " + databaseName + ".payload_bulk_import");
         // We do not do the "compute stats" for the view, since we get the following error: "COMPUTE STATS not supported for view: pdfaggregationdatabase_payloads_view.payload".