feat: add postgres response for trasaction related statements (#4562)

* feat: add postgres fixtures WIP

* feat: implement more postgres fixtures

* feat: add compatibility for transaction/set transaction/show transaction

* fix: improve regex for set transaction

src/common/function/src/system.rs

@@ -22,7 +22,7 @@ mod version;
 use std::sync::Arc;
 
 use build::BuildFunction;
-use database::DatabaseFunction;
+use database::{CurrentSchemaFunction, DatabaseFunction};
 use pg_catalog::PGCatalogFunction;
 use procedure_state::ProcedureStateFunction;
 use timezone::TimezoneFunction;
@@ -37,6 +37,7 @@ impl SystemFunction {
         registry.register(Arc::new(BuildFunction));
         registry.register(Arc::new(VersionFunction));
         registry.register(Arc::new(DatabaseFunction));
+        registry.register(Arc::new(CurrentSchemaFunction));
         registry.register(Arc::new(TimezoneFunction));
         registry.register_async(Arc::new(ProcedureStateFunction));
         PGCatalogFunction::register(registry);

src/common/function/src/system/database.rs

@@ -26,11 +26,35 @@ use crate::function::{Function, FunctionContext};
 #[derive(Clone, Debug, Default)]
 pub struct DatabaseFunction;
 
-const NAME: &str = "database";
+#[derive(Clone, Debug, Default)]
+pub struct CurrentSchemaFunction;
+
+const DATABASE_FUNCTION_NAME: &str = "database";
+const CURRENT_SCHEMA_FUNCTION_NAME: &str = "current_schema";
 
 impl Function for DatabaseFunction {
     fn name(&self) -> &str {
-        NAME
+        DATABASE_FUNCTION_NAME
+    }
+
+    fn return_type(&self, _input_types: &[ConcreteDataType]) -> Result<ConcreteDataType> {
+        Ok(ConcreteDataType::string_datatype())
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::uniform(0, vec![], Volatility::Immutable)
+    }
+
+    fn eval(&self, func_ctx: FunctionContext, _columns: &[VectorRef]) -> Result<VectorRef> {
+        let db = func_ctx.query_ctx.current_schema();
+
+        Ok(Arc::new(StringVector::from_slice(&[&db])) as _)
+    }
+}
+
+impl Function for CurrentSchemaFunction {
+    fn name(&self) -> &str {
+        CURRENT_SCHEMA_FUNCTION_NAME
     }
 
     fn return_type(&self, _input_types: &[ConcreteDataType]) -> Result<ConcreteDataType> {
@@ -54,6 +78,12 @@ impl fmt::Display for DatabaseFunction {
     }
 }
 
+impl fmt::Display for CurrentSchemaFunction {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "CURRENT_SCHEMA")
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use std::sync::Arc;

src/common/function/src/system/pg_catalog.rs

@@ -14,11 +14,13 @@
 
 mod pg_get_userbyid;
 mod table_is_visible;
+mod version;
 
 use std::sync::Arc;
 
 use pg_get_userbyid::PGGetUserByIdFunction;
 use table_is_visible::PGTableIsVisibleFunction;
+use version::PGVersionFunction;
 
 use crate::function_registry::FunctionRegistry;
 
@@ -35,5 +37,6 @@ impl PGCatalogFunction {
     pub fn register(registry: &FunctionRegistry) {
         registry.register(Arc::new(PGTableIsVisibleFunction));
         registry.register(Arc::new(PGGetUserByIdFunction));
+        registry.register(Arc::new(PGVersionFunction));
     }
 }

src/common/function/src/system/pg_catalog/version.rs

@@ -0,0 +1,54 @@
+// Copyright 2023 Greptime Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::sync::Arc;
+use std::{env, fmt};
+
+use common_query::error::Result;
+use common_query::prelude::{Signature, Volatility};
+use datatypes::data_type::ConcreteDataType;
+use datatypes::vectors::{StringVector, VectorRef};
+
+use crate::function::{Function, FunctionContext};
+
+#[derive(Clone, Debug, Default)]
+pub(crate) struct PGVersionFunction;
+
+impl fmt::Display for PGVersionFunction {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, crate::pg_catalog_func_fullname!("VERSION"))
+    }
+}
+
+impl Function for PGVersionFunction {
+    fn name(&self) -> &str {
+        crate::pg_catalog_func_fullname!("version")
+    }
+
+    fn return_type(&self, _input_types: &[ConcreteDataType]) -> Result<ConcreteDataType> {
+        Ok(ConcreteDataType::string_datatype())
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::exact(vec![], Volatility::Immutable)
+    }
+
+    fn eval(&self, _func_ctx: FunctionContext, _columns: &[VectorRef]) -> Result<VectorRef> {
+        let result = StringVector::from(vec![format!(
+            "PostgreSQL 16.3 GreptimeDB {}",
+            env!("CARGO_PKG_VERSION")
+        )]);
+        Ok(Arc::new(result))
+    }
+}