Fix: HANA always requires stored procedures (similar to SqlServer), Fix: default value on intermediate alters

ebean-api/src/main/java/io/ebean/config/dbplatform/hana/HanaPlatform.java

@@ -92,4 +92,8 @@ public class HanaPlatform extends DatabasePlatform {
     }
   }
 
+  @Override
+  public boolean isUseMigrationStoredProcedures() {
+    return true;
+  }
 }

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

@@ -57,19 +57,21 @@ public abstract class AbstractHanaDdl extends PlatformDdl {
       if (isNumberType(currentType)) {
         // numbers can always be converted to decimal
         buffer.append("alter table ").append(tableName).append(" ").append(alterColumn).append(" ").append(columnName)
-          .append(" decimal ").append(defaultValueClause).append(notnullClause).append(alterColumnSuffix)
-          .endOfStatement();
+            .append(" decimal ").append(notnullClause).append(alterColumnSuffix)
+            .endOfStatement();
 
       } else if (isStringType(currentType)) {
         // strings can always be converted to nclob
+        // Note: we do not add default clause here to avoid error[SAP DBTech JDBC: [336]: invalid default value:
+        // default value cannot be created on column of data type NCLOB 
         buffer.append("alter table ").append(tableName).append(" ").append(alterColumn).append(" ").append(columnName)
-          .append(" nclob ").append(defaultValueClause).append(notnullClause).append(alterColumnSuffix)
-          .endOfStatement();
+            .append(" nclob").append(notnullClause).append(alterColumnSuffix)
+            .endOfStatement();
       }
     }
 
     buffer.append("alter table ").append(tableName).append(" ").append(alterColumn).append(" ").append(columnName)
-      .append(" ").append(type).append(defaultValueClause).append(notnullClause).append(alterColumnSuffix);
+        .append(" ").append(type).append(defaultValueClause).append(notnullClause).append(alterColumnSuffix);
 
     return buffer.getBuffer();
   }

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

@@ -32,7 +32,7 @@ declare exit handler for sql_error_code 397 begin end;
 exec 'alter table migtest_e_basic drop constraint ck_migtest_e_basic_status2';
 end;
 $$;
-alter table migtest_e_basic alter ( status2 nclob  default 'N' not null);
+alter table migtest_e_basic alter ( status2 nclob not null);
 alter table migtest_e_basic alter ( status2 nvarchar(1) default 'N' not null);
 alter table migtest_e_basic add constraint ck_migtest_e_basic_status2 check ( status2 in ('N','A','I'));
 delimiter $$

ebean-test/src/test/resources/migrationtest/dbmigration/hana/I__create_procs.sql

@@ -0,0 +1,33 @@
+-- Inital script to create stored procedures etc for the hana platform
+delimiter $$
+--
+-- PROCEDURE: usp_ebean_drop_foreign_keys TABLE, COLUMN
+-- deletes all constraints and foreign keys referring to TABLE.COLUMN
+--
+CREATE OR REPLACE PROCEDURE usp_ebean_drop_foreign_keys(IN table_name NVARCHAR(256), IN column_name NVARCHAR(256))
+AS
+BEGIN
+DECLARE foreign_key_names TABLE(CONSTRAINT_NAME NVARCHAR(256), TABLE_NAME NVARCHAR(256));
+DECLARE i INT;
+
+foreign_key_names = SELECT CONSTRAINT_NAME, TABLE_NAME FROM SYS.REFERENTIAL_CONSTRAINTS WHERE SCHEMA_NAME=CURRENT_SCHEMA AND TABLE_NAME=UPPER(:table_name) AND COLUMN_NAME=UPPER(:column_name);
+
+FOR I IN 1 .. RECORD_COUNT(:foreign_key_names) DO
+EXEC 'ALTER TABLE "' || ESCAPE_DOUBLE_QUOTES(:foreign_key_names.TABLE_NAME[i]) || '" DROP CONSTRAINT "' || ESCAPE_DOUBLE_QUOTES(:foreign_key_names.CONSTRAINT_NAME[i]) || '"';
+END FOR;
+
+END;
+$$
+
+delimiter $$
+--
+-- PROCEDURE: usp_ebean_drop_column TABLE, COLUMN
+-- deletes the column and ensures that all indices and constraints are dropped first
+--
+CREATE OR REPLACE PROCEDURE usp_ebean_drop_column(IN table_name NVARCHAR(256), IN column_name NVARCHAR(256))
+AS
+BEGIN
+CALL usp_ebean_drop_foreign_keys(table_name, column_name);
+EXEC 'ALTER TABLE "' || UPPER(ESCAPE_DOUBLE_QUOTES(table_name)) || '" DROP ("' || UPPER(ESCAPE_DOUBLE_QUOTES(column_name)) || '")';
+END;
+$$

ebean-test/src/test/resources/migrationtest/dbmigration/hana/idx_hana.migrations

@@ -1,7 +1,8 @@
+-745347271,     I__create_procs.sql
 513351138,      1.0__initial.sql
 -1152055114,    1.1.sql
 1830946249,     1.2__dropsFor_1.1.sql
-1073423108,     1.3.sql
+744723875,      1.3.sql
 201970227,      1.4__dropsFor_1.3.sql
 1906063401,     R__order_views_hana.sql
 

ebean-test/testconfig/ebean-hana.properties

@@ -0,0 +1,6 @@
+# Note: You need a running docker container. See howto-test.md for details
+datasource.default=hana
+datasource.hana.username=SYSTEM
+datasource.hana.password=VeryVerySecret#1234
+datasource.hana.url=jdbc:sap://localhost:39041/
+

howto-test.md

@@ -43,3 +43,25 @@ Maven
 
 Use the `-Dprops.file` parameter to start the test cases for a certain platform.
 
+SAP HANA
+--------
+To set up a SAP HANA container, you may need a docker account to download the image
+
+1. Remove any existing HANA container with `docker rm hana`
+
+2. Create an empty directory (e.g. `/tmp/hana`)
+
+3. Create a `settings.json` file with content `{ "master_password": "VeryVerySecret#1234" }` in that directory
+
+4. Run the container, e.g with this command:
+
+```
+docker run -p 39013:39013 -p 39017:39017 -p 39041-39045:39041-39045 -p 1128-1129:1128-1129 -p 59013-59014:59013-59014 \
+    -v /tmp/hana:/hana/mounts \
+    --ulimit nofile=1048576:1048576 --sysctl kernel.shmmax=1073741824 
+    --sysctl net.ipv4.ip_local_port_range="40000 60999" --sysctl kernel.shmall=8388608 \
+    --name "hana"  store/saplabs/hanaexpress:2.00.045.00.20200121.1  \
+    --passwords-url file:///hana/mounts/settings.json --agree-to-sap-license
+```
+
+You can optionally add the `-d` parameter. Note, if you re-run that command, the best advice is to clear the data directory and recreate the settings.json file