Add special cases for Exasol VS Local modus: explicit cast to utf8 in…

… the case of char and varchar datatypes

src/main/java/com/exasol/adapter/dialects/exasol/ExasolLocalQueryRewriter.java

@@ -37,7 +37,7 @@ class ExasolLocalQueryRewriter implements QueryRewriter {
     public String rewrite(final SqlStatement statement, final List<DataType> selectListDataTypes,
             final ExaMetadata exaMetadata, final AdapterProperties properties) throws AdapterException {
         final SqlGenerationContext context = new SqlGenerationContext(properties.getCatalogName(),
-                properties.getSchemaName(), false);
+                properties.getSchemaName(), true);
         final SqlGenerator sqlGeneratorVisitor = this.dialect.getSqlGenerator(context);
         final String selectStatement = sqlGeneratorVisitor.generateSqlFor(statement);
         LOGGER.finer(() -> "SELECT push-down statement:\n" + selectStatement);

src/main/java/com/exasol/adapter/dialects/exasol/ExasolLocalSqlGenerationVisitor.java

@@ -0,0 +1,40 @@
+package com.exasol.adapter.dialects.exasol;
+
+import com.exasol.adapter.AdapterException;
+import com.exasol.adapter.dialects.SqlDialect;
+import com.exasol.adapter.dialects.rewriting.SqlGenerationContext;
+import com.exasol.adapter.metadata.DataType;
+import com.exasol.adapter.sql.SqlColumn;
+
+public class ExasolLocalSqlGenerationVisitor extends ExasolSqlGenerationVisitor{
+    /**
+     * Creates a new instance of the {@link ExasolSqlGenerationVisitor}.
+     *
+     * @param dialect {@link ExasolSqlDialect} dialect
+     * @param context SQL generation context
+     */
+    ExasolLocalSqlGenerationVisitor(SqlDialect dialect, SqlGenerationContext context) {
+        super(dialect, context);
+    }
+    @Override
+    public String visit(final SqlColumn column) throws AdapterException {
+        ExasolSqlDialect exasolSqlDialect = new ExasolSqlDialect(null,null);
+        String tablePrefix = "";
+        if (column.hasTableAlias()) {
+            tablePrefix = exasolSqlDialect.applyQuote(column.getTableAlias())
+                    + exasolSqlDialect.getTableCatalogAndSchemaSeparator();
+        } else if ((column.getTableName() != null) && !column.getTableName().isEmpty()) {
+            tablePrefix = exasolSqlDialect.applyQuote(column.getTableName())
+                    + exasolSqlDialect.getTableCatalogAndSchemaSeparator();
+        }
+        //PROVIDE A CAST TO CORRESPONDING DATATYPE WITH THE SAME LENGTH BUT WITH UTF8 AS CHARSET
+        if (column.getMetadata().getType().getExaDataType() == DataType.ExaDataType.CHAR || //
+                column.getMetadata().getType().getExaDataType() == DataType.ExaDataType.VARCHAR) {
+            int size = column.getMetadata().getType().getSize();
+            String dataTypeStr = column.getMetadata().getType().getExaDataType() == DataType.ExaDataType.CHAR ? "CHAR":"VARCHAR";
+            return "CAST(" + tablePrefix + exasolSqlDialect.applyQuote(column.getName())+" AS "+ dataTypeStr+"("+size+") UTF8)";
+        } else {
+            return tablePrefix + exasolSqlDialect.applyQuote(column.getName());
+        }
+    }
+}

src/main/java/com/exasol/adapter/dialects/exasol/ExasolSqlDialect.java

@@ -155,7 +155,12 @@ public String getStringLiteral(final String value) {
 
     @Override
     public SqlGenerator getSqlGenerator(final SqlGenerationContext context) {
-        return new ExasolSqlGenerationVisitor(this, context);
+        if (context.isLocal()){
+            return new ExasolLocalSqlGenerationVisitor(this, context);
+        } else {
+            return new ExasolSqlGenerationVisitor(this, context);
+        }
+
     }
 
     /**