Output "may loose settings" warning on mysql/mariadb for more impacte…

…d change types (#3045)

* Add "may lose column details" warning for addComment on mysql
* Keep warning messages from being duplicated

liquibase-core/src/main/java/liquibase/changelog/DatabaseChangeLog.java

@@ -19,6 +19,7 @@
 import liquibase.precondition.core.PreconditionContainer;
 import liquibase.resource.ResourceAccessor;
 import liquibase.servicelocator.LiquibaseService;
+import liquibase.ui.UIService;
 import liquibase.util.StringUtil;
 import liquibase.util.FilenameUtil;
 
@@ -299,8 +300,9 @@ public void validate(Database database, Contexts contexts, LabelExpression label
         validatingVisitor.validate(database, this);
         logIterator.run(validatingVisitor, new RuntimeEnvironment(database, contexts, labelExpression));
 
+        final Logger log = Scope.getCurrentScope().getLog(getClass());
         for (String message : validatingVisitor.getWarnings().getMessages()) {
-            Scope.getCurrentScope().getLog(getClass()).warning(message);
+            log.warning(message);
         }
 
         if (!validatingVisitor.validationPassed()) {

liquibase-core/src/main/java/liquibase/database/core/MySQLDatabase.java

@@ -2,9 +2,11 @@
 
 import liquibase.CatalogAndSchema;
 import liquibase.Scope;
+import liquibase.change.Change;
 import liquibase.database.AbstractJdbcDatabase;
 import liquibase.database.DatabaseConnection;
 import liquibase.exception.DatabaseException;
+import liquibase.exception.Warnings;
 import liquibase.executor.ExecutorService;
 import liquibase.statement.DatabaseFunction;
 import liquibase.statement.core.RawSqlStatement;
@@ -661,4 +663,8 @@ private int extractPrecision(DatabaseFunction databaseFunction) {
         }
         return precision;
     }
+
+    public void warnAboutAlterColumn(String changeName, Warnings warnings ) {
+        warnings.addWarning("Due to " + this.getShortName() + " SQL limitations, " + changeName + " will lose primary key/autoincrement/not null/comment settings explicitly redefined in the change. Use <sql> or <modifySql> to re-specify all configuration if this is the case");
+    }
 }

liquibase-core/src/main/java/liquibase/exception/Warnings.java

@@ -1,11 +1,11 @@
 package liquibase.exception;
 
-import java.util.ArrayList;
-import java.util.List;
+import java.util.*;
 
 public class Warnings {
 
-    private List<String> messages = new ArrayList<>();
+    //use linkedHashSet to keep them in order, but don't duplicate warnings that have already been logged
+    private final LinkedHashSet<String> messages = new LinkedHashSet<>();
 
     public Warnings addWarning(String warning) {
         messages.add(warning);
@@ -20,7 +20,7 @@ public Warnings addAll(Warnings warnings) {
     }
 
     public List<String> getMessages() {
-        return messages;
+        return new ArrayList<>(messages);
     }
 
     public boolean hasWarnings() {

liquibase-core/src/main/java/liquibase/sqlgenerator/core/AddDefaultValueGenerator.java

@@ -2,17 +2,20 @@
 
 import liquibase.database.Database;
 import liquibase.database.core.HsqlDatabase;
+import liquibase.database.core.MySQLDatabase;
 import liquibase.datatype.DataTypeFactory;
 import liquibase.datatype.LiquibaseDataType;
 import liquibase.datatype.core.BooleanType;
 import liquibase.datatype.core.CharType;
 import liquibase.exception.ValidationErrors;
+import liquibase.exception.Warnings;
 import liquibase.sql.Sql;
 import liquibase.sql.UnparsedSql;
 import liquibase.sqlgenerator.SqlGeneratorChain;
 import liquibase.statement.DatabaseFunction;
 import liquibase.statement.SequenceNextValueFunction;
 import liquibase.statement.core.AddDefaultValueStatement;
+import liquibase.statement.core.ModifyDataTypeStatement;
 import liquibase.structure.core.Column;
 import liquibase.structure.core.Schema;
 import liquibase.structure.core.Table;
@@ -61,6 +64,17 @@ public ValidationErrors validate(AddDefaultValueStatement addDefaultValueStateme
         return validationErrors;
     }
 
+    @Override
+    public Warnings warn(AddDefaultValueStatement statement, Database database, SqlGeneratorChain sqlGeneratorChain) {
+        Warnings warnings = super.warn(statement, database, sqlGeneratorChain);
+
+        if (database instanceof MySQLDatabase) {
+            ((MySQLDatabase) database).warnAboutAlterColumn("addDefaultValue", warnings);
+        }
+
+        return warnings;
+    }
+
     @Override
     public Sql[] generateSql(AddDefaultValueStatement statement, Database database, SqlGeneratorChain sqlGeneratorChain) {
         Object defaultValue = statement.getDefaultValue();

liquibase-core/src/main/java/liquibase/sqlgenerator/core/ModifyDataTypeGenerator.java

@@ -27,9 +27,8 @@ public boolean supports(ModifyDataTypeStatement statement, Database database) {
     public Warnings warn(ModifyDataTypeStatement modifyDataTypeStatement, Database database, SqlGeneratorChain sqlGeneratorChain) {
         Warnings warnings = super.warn(modifyDataTypeStatement, database, sqlGeneratorChain);
 
-        if ((database instanceof MySQLDatabase) && !modifyDataTypeStatement.getNewDataType().toLowerCase().contains
-            ("varchar")) {
-            warnings.addWarning("modifyDataType will lose primary key/autoincrement/not null settings for mysql.  Use <sql> and re-specify all configuration if this is the case");
+        if (database instanceof MySQLDatabase) {
+            ((MySQLDatabase) database).warnAboutAlterColumn("modifyDataType", warnings);
         }
 
         return warnings;

liquibase-core/src/main/java/liquibase/sqlgenerator/core/SetColumnRemarksGenerator.java

@@ -4,6 +4,7 @@
 import liquibase.database.core.*;
 import liquibase.datatype.DataTypeFactory;
 import liquibase.exception.ValidationErrors;
+import liquibase.exception.Warnings;
 import liquibase.sql.Sql;
 import liquibase.sql.UnparsedSql;
 import liquibase.sqlgenerator.SqlGeneratorChain;
@@ -37,6 +38,16 @@ public ValidationErrors validate(SetColumnRemarksStatement setColumnRemarksState
         return validationErrors;
     }
 
+    @Override
+    public Warnings warn(SetColumnRemarksStatement statementType, Database database, SqlGeneratorChain<SetColumnRemarksStatement> sqlGeneratorChain) {
+        final Warnings warnings = super.warn(statementType, database, sqlGeneratorChain);
+        if (database instanceof MySQLDatabase) {
+            ((MySQLDatabase) database).warnAboutAlterColumn("setColumnRemarks", warnings);
+        }
+
+        return warnings;
+    }
+
     @Override
     public Sql[] generateSql(SetColumnRemarksStatement statement, Database database, SqlGeneratorChain sqlGeneratorChain) {
 

liquibase-core/src/main/java/liquibase/sqlgenerator/core/SetNullableGenerator.java

@@ -5,10 +5,12 @@
 import liquibase.datatype.DataTypeFactory;
 import liquibase.exception.DatabaseException;
 import liquibase.exception.ValidationErrors;
+import liquibase.exception.Warnings;
 import liquibase.sql.Sql;
 import liquibase.sql.UnparsedSql;
 import liquibase.sqlgenerator.SqlGeneratorChain;
 import liquibase.sqlgenerator.SqlGeneratorFactory;
+import liquibase.statement.core.AddDefaultValueStatement;
 import liquibase.statement.core.ReorganizeTableStatement;
 import liquibase.statement.core.SetNullableStatement;
 import liquibase.structure.core.Column;
@@ -58,6 +60,17 @@ public ValidationErrors validate(SetNullableStatement setNullableStatement, Data
         return validationErrors;
     }
 
+    @Override
+    public Warnings warn(SetNullableStatement statement, Database database, SqlGeneratorChain sqlGeneratorChain) {
+        Warnings warnings = super.warn(statement, database, sqlGeneratorChain);
+
+        if (database instanceof MySQLDatabase) {
+            ((MySQLDatabase) database).warnAboutAlterColumn("setNullable", warnings);
+        }
+
+        return warnings;
+    }
+
     @Override
     public Sql[] generateSql(SetNullableStatement statement, Database database, SqlGeneratorChain sqlGeneratorChain) {
         String sql;