#2026 - Postgres DDL - modify type generates wrong alter sql. Needs explicit cast / using clause.

src/main/java/io/ebeaninternal/dbmigration/ddlgeneration/platform/PostgresDdl.java

@@ -54,4 +54,9 @@ public class PostgresDdl extends PlatformDdl {
   public String asIdentityColumn(String columnDefn, DdlIdentity identity) {
     return asIdentityStandardOptions(columnDefn, identity);
   }
+
+  @Override
+  public String alterColumnType(String tableName, String columnName, String type) {
+    return super.alterColumnType(tableName, columnName, type) + " using " + columnName + "::" + convert(type);
+  }
 }

src/test/java/io/ebeaninternal/dbmigration/ddlgeneration/platform/PlatformDdl_AlterColumnTest.java

@@ -20,12 +20,12 @@ import static org.junit.Assert.assertTrue;
 
 public class PlatformDdl_AlterColumnTest {
 
-  private PlatformDdl h2Ddl = PlatformDdlBuilder.create(new H2Platform());
-  private PlatformDdl pgDdl = PlatformDdlBuilder.create(new PostgresPlatform());
-  private PlatformDdl mysqlDdl = PlatformDdlBuilder.create(new MySqlPlatform());
-  private PlatformDdl oraDdl = PlatformDdlBuilder.create(new OraclePlatform());
-  private PlatformDdl sqlServerDdl = PlatformDdlBuilder.create(new SqlServer17Platform());
-  private PlatformDdl hanaDdl = PlatformDdlBuilder.create(new HanaPlatform());
+  private final PlatformDdl h2Ddl = PlatformDdlBuilder.create(new H2Platform());
+  private final PlatformDdl pgDdl = PlatformDdlBuilder.create(new PostgresPlatform());
+  private final PlatformDdl mysqlDdl = PlatformDdlBuilder.create(new MySqlPlatform());
+  private final PlatformDdl oraDdl = PlatformDdlBuilder.create(new OraclePlatform());
+  private final PlatformDdl sqlServerDdl = PlatformDdlBuilder.create(new SqlServer17Platform());
+  private final PlatformDdl hanaDdl = PlatformDdlBuilder.create(new HanaPlatform());
 
   {
     ServerConfig serverConfig = Ebean.getDefaultServer().getPluginApi().getServerConfig();
@@ -122,7 +122,9 @@ public class PlatformDdl_AlterColumnTest {
     assertEquals("alter table mytab alter column acol varchar(20)", sql);
 
     sql = pgDdl.alterColumnType("mytab", "acol", "varchar(20)");
-    assertEquals("alter table mytab alter column acol type varchar(20)", sql);
+    assertEquals("alter table mytab alter column acol type varchar(20) using acol::varchar(20)", sql);
+    sql = pgDdl.alterColumnType("mytab", "acol", "bigint");
+    assertEquals("alter table mytab alter column acol type bigint using acol::bigint", sql);
 
     sql = oraDdl.alterColumnType("mytab", "acol", "varchar(20)");
     assertEquals("alter table mytab modify acol varchar2(20)", sql);

src/test/resources/dbmigration/migrationtest/postgres/1.1.sql

@@ -42,7 +42,7 @@ alter table migtest_e_basic alter column status set default 'A';
 alter table migtest_e_basic alter column status set not null;
 alter table migtest_e_basic add constraint ck_migtest_e_basic_status check ( status in ('N','A','I','?'));
 alter table migtest_e_basic drop constraint if exists ck_migtest_e_basic_status2;
-alter table migtest_e_basic alter column status2 type varchar(127);
+alter table migtest_e_basic alter column status2 type varchar(127) using status2::varchar(127);
 alter table migtest_e_basic alter column status2 drop default;
 alter table migtest_e_basic alter column status2 drop not null;
 
@@ -71,7 +71,7 @@ alter table migtest_e_enum drop constraint if exists ck_migtest_e_enum_test_stat
 
 alter table migtest_e_history alter column test_string TYPE bigint USING (test_string::integer);
 comment on column migtest_e_history.test_string is 'Column altered to long now';
-alter table migtest_e_history alter column test_string type bigint;
+alter table migtest_e_history alter column test_string type bigint using test_string::bigint;
 comment on table migtest_e_history is 'We have history now';
 
 -- NOTE: table has @History - special migration may be necessary
@@ -85,8 +85,8 @@ alter table migtest_e_history2_history add column test_string2 varchar(255);
 alter table migtest_e_history2_history add column test_string3 varchar(255) default 'unknown';
 alter table migtest_e_history2_history add column new_column varchar(20);
 
-alter table migtest_e_history4 alter column test_number type bigint;
-alter table migtest_e_history4_history alter column test_number type bigint;
+alter table migtest_e_history4 alter column test_number type bigint using test_number::bigint;
+alter table migtest_e_history4_history alter column test_number type bigint using test_number::bigint;
 alter table migtest_e_history5 add column test_boolean boolean default false not null;
 alter table migtest_e_history5_history add column test_boolean boolean default false;
 

src/test/resources/dbmigration/migrationtest/postgres/1.3.sql

@@ -26,7 +26,7 @@ alter table migtest_e_basic add constraint ck_migtest_e_basic_status check ( sta
 
 update migtest_e_basic set status2 = 'N' where status2 is null;
 alter table migtest_e_basic drop constraint if exists ck_migtest_e_basic_status2;
-alter table migtest_e_basic alter column status2 type varchar(1);
+alter table migtest_e_basic alter column status2 type varchar(1) using status2::varchar(1);
 alter table migtest_e_basic alter column status2 set default 'N';
 alter table migtest_e_basic alter column status2 set not null;
 alter table migtest_e_basic add constraint ck_migtest_e_basic_status2 check ( status2 in ('N','A','I'));
@@ -57,8 +57,8 @@ alter table migtest_e_history2 add column obsolete_string2 varchar(255);
 alter table migtest_e_history2_history add column obsolete_string1 varchar(255);
 alter table migtest_e_history2_history add column obsolete_string2 varchar(255);
 
-alter table migtest_e_history4 alter column test_number type integer;
-alter table migtest_e_history4_history alter column test_number type integer;
+alter table migtest_e_history4 alter column test_number type integer using test_number::integer;
+alter table migtest_e_history4_history alter column test_number type integer using test_number::integer;
 alter table migtest_e_history6 alter column test_number1 drop default;
 alter table migtest_e_history6 alter column test_number1 drop not null;