fix(csharp): address issue #525

Author: peco-engineer-bot[bot]

csharp/src/StatementExecution/MetadataCommands/MetadataCommandBase.cs

@@ -92,12 +92,24 @@ protected static string ConvertPattern(string? pattern)
             return result.ToString();
         }
 
+        /// <summary>
+        /// Determines whether a catalog scope argument means "all catalogs".
+        /// A null catalog, or the bare SQL-LIKE wildcard "%", both expand to every
+        /// catalog. This keeps SEA in step with Thrift, where a "%" catalog enumerates
+        /// all catalogs rather than matching a single (non-existent) catalog literally
+        /// named "%". See issue #525.
+        /// </summary>
+        protected static bool IsAllCatalogsScope(string? catalog)
+        {
+            return catalog == null || catalog == "%";
+        }
+
         protected static void AppendCatalogScope(StringBuilder sql, string? catalog)
         {
-            if (catalog == null)
+            if (IsAllCatalogsScope(catalog))
                 sql.Append(InAllCatalogs);
             else
-                sql.Append(string.Format(InCatalogFormat, QuoteIdentifier(catalog)));
+                sql.Append(string.Format(InCatalogFormat, QuoteIdentifier(catalog!)));
         }
     }
 }

csharp/src/StatementExecution/MetadataCommands/ShowSchemasCommand.cs

@@ -32,10 +32,10 @@ public ShowSchemasCommand(string? catalog, string? schemaPattern = null)
         public override string Build()
         {
             var sql = new StringBuilder("SHOW SCHEMAS");
-            if (_catalog == null)
+            if (IsAllCatalogsScope(_catalog))
                 sql.Append(InAllCatalogs);
             else
-                sql.Append($" IN {QuoteIdentifier(_catalog)}");
+                sql.Append($" IN {QuoteIdentifier(_catalog!)}");
             if (_schemaPattern != null)
                 sql.Append(string.Format(LikeFormat, ConvertPattern(_schemaPattern)));
             return sql.ToString();

csharp/test/Unit/StatementExecution/ShowCommandTests.cs

@@ -69,6 +69,24 @@ public void ShowSchemas_CatalogWithBacktick()
             Assert.Equal("SHOW SCHEMAS IN `my``catalog`", new ShowSchemasCommand("my`catalog").Build());
         }
 
+        // Catalog "%" wildcard semantics (issue #525): a "%" catalog scope must mean
+        // "all catalogs" on the SEA path, matching Thrift, rather than being quoted as
+        // a literal identifier (`%`) that matches a non-existent catalog.
+
+        [Fact]
+        public void ShowSchemas_PercentCatalog_UsesAllCatalogs()
+        {
+            Assert.Equal("SHOW SCHEMAS IN ALL CATALOGS", new ShowSchemasCommand("%").Build());
+        }
+
+        [Fact]
+        public void ShowSchemas_PercentCatalogWithSchemaPattern_UsesAllCatalogs()
+        {
+            Assert.Equal(
+                "SHOW SCHEMAS IN ALL CATALOGS LIKE 'def*'",
+                new ShowSchemasCommand("%", "def%").Build());
+        }
+
         // ShowTablesCommand
 
         [Fact]
@@ -83,6 +101,18 @@ public void ShowTables_WithCatalog()
             Assert.Equal("SHOW TABLES IN CATALOG `main`", new ShowTablesCommand("main").Build());
         }
 
+        [Fact]
+        public void ShowTables_PercentCatalog_UsesAllCatalogs()
+        {
+            Assert.Equal("SHOW TABLES IN ALL CATALOGS", new ShowTablesCommand("%").Build());
+        }
+
+        [Fact]
+        public void ShowColumns_PercentCatalog_UsesAllCatalogs()
+        {
+            Assert.Equal("SHOW COLUMNS IN ALL CATALOGS", new ShowColumnsCommand("%").Build());
+        }
+
         [Fact]
         public void ShowTables_WithCatalogAndSchema()
         {