Postgres DDL - Don't use cast when just changing varchar column size

ebean-ddl-generator/src/main/java/io/ebeaninternal/dbmigration/ddlgeneration/platform/PostgresDdl.java

@@ -9,7 +9,7 @@ import io.ebeaninternal.dbmigration.migration.Column;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
-import java.util.stream.Collectors;
+import java.util.regex.Pattern;
 
 import static java.util.stream.Collectors.toList;
 
@@ -18,6 +18,8 @@ import static java.util.stream.Collectors.toList;
  */
 public class PostgresDdl extends PlatformDdl {
 
+  private static final Pattern PLAIN_VARCHAR = Pattern.compile("(varchar\\()(\\d+)(\\))");
+
   private static final String dropIndexConcurrentlyIfExists = "drop index concurrently if exists ";
 
   public PostgresDdl(DatabasePlatform platform) {
@@ -74,9 +76,20 @@ public class PostgresDdl extends PlatformDdl {
   @Override
   protected void alterColumnType(DdlWrite writer, AlterColumn alter) {
     String type = convert(alter.getType());
-    alterTable(writer, alter.getTableName()).append(alterColumn, alter.getColumnName())
-      .append(columnSetType).append(type)
-      .append(" using ").append(alter.getColumnName()).append("::").append(type);
+    var alterTable = alterTable(writer, alter.getTableName())
+      .append(alterColumn, alter.getColumnName())
+      .append(columnSetType).append(type);
+    if (useCast(type, alter.getCurrentType())) {
+      alterTable.append(" using ").append(alter.getColumnName()).append("::").append(type);
+    }
+  }
+
+  static boolean useCast(String newType, String currentType) {
+    return currentType == null || !isPlainVarchar(newType) || !isPlainVarchar(currentType);
+  }
+
+  static boolean isPlainVarchar(String type) {
+    return PLAIN_VARCHAR.matcher(type).matches();
   }
 
   @Override

ebean-ddl-generator/src/test/java/io/ebeaninternal/dbmigration/ddlgeneration/platform/PlatformDdl_AlterColumnTest.java

@@ -107,7 +107,7 @@ public class PlatformDdl_AlterColumnTest {
 
     sql = alterColumn(pgDdl, alter);
     softly.assertThat(sql).isEqualTo("-- apply alter tables\n"
-      + "alter table mytab alter column acol type varchar(50) using acol::varchar(50);\n"
+      + "alter table mytab alter column acol type varchar(50);\n"
       + "alter table mytab alter column acol set default 'hi';\n"
       + "alter table mytab alter column acol set not null;\n");
 

ebean-ddl-generator/src/test/java/io/ebeaninternal/dbmigration/ddlgeneration/platform/PostgresDdlTest.java

@@ -13,6 +13,41 @@ class PostgresDdlTest {
 
   final PostgresDdl postgresDdl = new PostgresDdl(new PostgresPlatform());
 
+  @Test
+  void useCast_notWhenSimpleVarcharLengthChange() {
+    assertThat(PostgresDdl.useCast("varchar(10)", "varchar(150)")).isFalse();
+  }
+
+  @Test
+  void useCast() {
+    assertThat(PostgresDdl.useCast("varchar", "varchar(150)")).isTrue();
+    assertThat(PostgresDdl.useCast("varchar(1)", "varchar")).isTrue();
+    assertThat(PostgresDdl.useCast("varchar(1)[]", "varchar(2)[]")).isTrue();
+  }
+
+  @Test
+  void useCastTrue() {
+    assertThat(PostgresDdl.useCast("text(10)", "text(150)")).isTrue();
+    assertThat(PostgresDdl.useCast("number(5)", "number(10)")).isTrue();
+    assertThat(PostgresDdl.useCast("number(5,3)", "number(10,2)")).isTrue();
+  }
+
+  @Test
+  void isPlainVarchar() {
+    assertThat(PostgresDdl.isPlainVarchar("varchar(1)")).isTrue();
+    assertThat(PostgresDdl.isPlainVarchar("varchar(10)")).isTrue();
+    assertThat(PostgresDdl.isPlainVarchar("varchar(150)")).isTrue();
+  }
+
+  @Test
+  void isPlainVarchar_false() {
+    assertThat(PostgresDdl.isPlainVarchar("varcha(10)")).isFalse();
+    assertThat(PostgresDdl.isPlainVarchar("text(10)")).isFalse();
+    assertThat(PostgresDdl.isPlainVarchar("number(10)")).isFalse();
+    assertThat(PostgresDdl.isPlainVarchar("varchar(10)[]")).isFalse();
+    assertThat(PostgresDdl.isPlainVarchar("varchar")).isFalse();
+  }
+
   @Test
   void setLockTimeout() {
     final String sql = postgresDdl.setLockTimeout(5);

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

@@ -86,7 +86,7 @@ alter table migtest_ckey_detail add column two_key varchar(127);
 alter table migtest_ckey_parent add column assoc_id integer;
 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 alter column status2 type varchar(127) using status2::varchar(127);
+alter table migtest_e_basic alter column status2 type varchar(127);
 alter table migtest_e_basic alter column status2 drop default;
 alter table migtest_e_basic alter column status2 drop not null;
 alter table migtest_e_basic alter column a_lob drop default;

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

@@ -68,7 +68,7 @@ update migtest_e_history6 set test_number2 = 7 where test_number2 is null;
 -- apply alter tables
 alter table migtest_e_basic alter column status drop default;
 alter table migtest_e_basic alter column status drop not null;
-alter table migtest_e_basic alter column status2 type varchar(1) using status2::varchar(1);
+alter table migtest_e_basic alter column status2 type 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 alter column a_lob type varchar(255) using a_lob::varchar(255);

ebean-test/src/test/resources/migrationtest/dbmigration/postgres/idx_postgres.migrations

@@ -1,7 +1,7 @@
 -73982981,      1.0__initial.sql
--1076179036,    1.1.sql
+-167317190,     1.1.sql
 274267648,      1.2__dropsFor_1.1.sql
--634032267,     1.3.sql
+-42523216,      1.3.sql
 -709144111,     1.4__dropsFor_1.3.sql
 783227075,      R__multi_comments.sql
 561281075,      R__order_views.sql

ebean-test/src/test/resources/migrationtest/dbmigration/postgres9/1.1.sql

@@ -86,7 +86,7 @@ alter table migtest_ckey_detail add column two_key varchar(127);
 alter table migtest_ckey_parent add column assoc_id integer;
 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 alter column status2 type varchar(127) using status2::varchar(127);
+alter table migtest_e_basic alter column status2 type varchar(127);
 alter table migtest_e_basic alter column status2 drop default;
 alter table migtest_e_basic alter column status2 drop not null;
 alter table migtest_e_basic alter column a_lob drop default;

ebean-test/src/test/resources/migrationtest/dbmigration/postgres9/1.3.sql

@@ -68,7 +68,7 @@ update migtest_e_history6 set test_number2 = 7 where test_number2 is null;
 -- apply alter tables
 alter table migtest_e_basic alter column status drop default;
 alter table migtest_e_basic alter column status drop not null;
-alter table migtest_e_basic alter column status2 type varchar(1) using status2::varchar(1);
+alter table migtest_e_basic alter column status2 type 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 alter column a_lob type varchar(255) using a_lob::varchar(255);

ebean-test/src/test/resources/migrationtest/dbmigration/postgres9/idx_postgres.migrations

@@ -1,7 +1,7 @@
 -1033742102,    1.0__initial.sql
--1861202915,    1.1.sql
+382308009,      1.1.sql
 274267648,      1.2__dropsFor_1.1.sql
-601885195,      1.3.sql
+2062205426,     1.3.sql
 -709144111,     1.4__dropsFor_1.3.sql
 783227075,      R__multi_comments.sql
 561281075,      R__order_views.sql

ebean-test/src/test/resources/migrationtest/dbmigration/yugabyte/1.1.sql

@@ -81,7 +81,7 @@ alter table migtest_ckey_detail add column two_key varchar(127);
 alter table migtest_ckey_parent add column assoc_id integer;
 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 alter column status2 type varchar(127) using status2::varchar(127);
+alter table migtest_e_basic alter column status2 type varchar(127);
 alter table migtest_e_basic alter column status2 drop default;
 alter table migtest_e_basic alter column status2 drop not null;
 alter table migtest_e_basic alter column a_lob drop default;

ebean-test/src/test/resources/migrationtest/dbmigration/yugabyte/1.3.sql

@@ -68,7 +68,7 @@ update migtest_e_history6 set test_number2 = 7 where test_number2 is null;
 -- apply alter tables
 alter table migtest_e_basic alter column status drop default;
 alter table migtest_e_basic alter column status drop not null;
-alter table migtest_e_basic alter column status2 type varchar(1) using status2::varchar(1);
+alter table migtest_e_basic alter column status2 type 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 alter column a_lob type varchar(255) using a_lob::varchar(255);

ebean-test/src/test/resources/migrationtest/dbmigration/yugabyte/idx_yugabyte.migrations

@@ -1,7 +1,7 @@
 113365976,      1.0__initial.sql
-637070078,      1.1.sql
+716377547,      1.1.sql
 274267648,      1.2__dropsFor_1.1.sql
--1383541363,    1.3.sql
+-1802768940,    1.3.sql
 -709144111,     1.4__dropsFor_1.3.sql
 561281075,      R__order_views.sql