feat: support pg_database for DBeaver.

src/catalog/src/system_schema/pg_catalog.rs

@@ -14,6 +14,7 @@
 
 mod pg_catalog_memory_table;
 mod pg_class;
+mod pg_database;
 mod pg_namespace;
 mod table_names;
 
@@ -26,6 +27,7 @@ use lazy_static::lazy_static;
 use paste::paste;
 use pg_catalog_memory_table::get_schema_columns;
 use pg_class::PGClass;
+use pg_database::PGDatabase;
 use pg_namespace::PGNamespace;
 use session::context::{Channel, QueryContext};
 use table::TableRef;
@@ -113,6 +115,10 @@ impl PGCatalogProvider {
             PG_CLASS.to_string(),
             self.build_table(PG_CLASS).expect(PG_NAMESPACE),
         );
+        tables.insert(
+            PG_DATABASE.to_string(),
+            self.build_table(PG_DATABASE).expect(PG_DATABASE),
+        );
         self.tables = tables;
     }
 }
@@ -135,6 +141,11 @@ impl SystemSchemaProviderInner for PGCatalogProvider {
                 self.catalog_manager.clone(),
                 self.namespace_oid_map.clone(),
             ))),
+            table_names::PG_DATABASE => Some(Arc::new(PGDatabase::new(
+                self.catalog_name.clone(),
+                self.catalog_manager.clone(),
+                self.namespace_oid_map.clone(),
+            ))),
             _ => None,
         }
     }

src/catalog/src/system_schema/pg_catalog/pg_database.rs

@@ -0,0 +1,214 @@
+// 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, Weak};
+
+use arrow_schema::SchemaRef as ArrowSchemaRef;
+use common_catalog::consts::PG_CATALOG_PG_DATABASE_TABLE_ID;
+use common_error::ext::BoxedError;
+use common_recordbatch::adapter::RecordBatchStreamAdapter;
+use common_recordbatch::{DfSendableRecordBatchStream, RecordBatch};
+use datafusion::execution::TaskContext;
+use datafusion::physical_plan::stream::RecordBatchStreamAdapter as DfRecordBatchStreamAdapter;
+use datafusion::physical_plan::streaming::PartitionStream as DfPartitionStream;
+use datatypes::scalars::ScalarVectorBuilder;
+use datatypes::schema::{Schema, SchemaRef};
+use datatypes::value::Value;
+use datatypes::vectors::{StringVectorBuilder, UInt32VectorBuilder, VectorRef};
+use snafu::{OptionExt, ResultExt};
+use store_api::storage::ScanRequest;
+
+use super::pg_namespace::oid_map::PGNamespaceOidMapRef;
+use super::{query_ctx, OID_COLUMN_NAME, PG_DATABASE};
+use crate::error::{
+    CreateRecordBatchSnafu, InternalSnafu, Result, UpgradeWeakCatalogManagerRefSnafu,
+};
+use crate::information_schema::Predicates;
+use crate::system_schema::utils::tables::{string_column, u32_column};
+use crate::system_schema::SystemTable;
+use crate::CatalogManager;
+
+// === column name ===
+pub const DATNAME: &str = "datname";
+
+/// The initial capacity of the vector builders.
+const INIT_CAPACITY: usize = 42;
+
+/// The `pg_catalog.database` table implementation.
+pub(super) struct PGDatabase {
+    schema: SchemaRef,
+    catalog_name: String,
+    catalog_manager: Weak<dyn CatalogManager>,
+
+    // Workaround to convert schema_name to a numeric id
+    namespace_oid_map: PGNamespaceOidMapRef,
+}
+
+impl PGDatabase {
+    pub(super) fn new(
+        catalog_name: String,
+        catalog_manager: Weak<dyn CatalogManager>,
+        namespace_oid_map: PGNamespaceOidMapRef,
+    ) -> Self {
+        Self {
+            schema: Self::schema(),
+            catalog_name,
+            catalog_manager,
+            namespace_oid_map,
+        }
+    }
+
+    fn schema() -> SchemaRef {
+        Arc::new(Schema::new(vec![
+            u32_column(OID_COLUMN_NAME),
+            string_column(DATNAME),
+        ]))
+    }
+
+    fn builder(&self) -> PGCDatabaseBuilder {
+        PGCDatabaseBuilder::new(
+            self.schema.clone(),
+            self.catalog_name.clone(),
+            self.catalog_manager.clone(),
+            self.namespace_oid_map.clone(),
+        )
+    }
+}
+
+impl DfPartitionStream for PGDatabase {
+    fn schema(&self) -> &ArrowSchemaRef {
+        self.schema.arrow_schema()
+    }
+
+    fn execute(&self, _: Arc<TaskContext>) -> DfSendableRecordBatchStream {
+        let schema = self.schema.arrow_schema().clone();
+        let mut builder = self.builder();
+        Box::pin(DfRecordBatchStreamAdapter::new(
+            schema,
+            futures::stream::once(async move {
+                builder
+                    .make_database(None)
+                    .await
+                    .map(|x| x.into_df_record_batch())
+                    .map_err(Into::into)
+            }),
+        ))
+    }
+}
+
+impl SystemTable for PGDatabase {
+    fn table_id(&self) -> table::metadata::TableId {
+        PG_CATALOG_PG_DATABASE_TABLE_ID
+    }
+
+    fn table_name(&self) -> &'static str {
+        PG_DATABASE
+    }
+
+    fn schema(&self) -> SchemaRef {
+        self.schema.clone()
+    }
+
+    fn to_stream(
+        &self,
+        request: ScanRequest,
+    ) -> Result<common_recordbatch::SendableRecordBatchStream> {
+        let schema = self.schema.arrow_schema().clone();
+        let mut builder = self.builder();
+        let stream = Box::pin(DfRecordBatchStreamAdapter::new(
+            schema,
+            futures::stream::once(async move {
+                builder
+                    .make_database(Some(request))
+                    .await
+                    .map(|x| x.into_df_record_batch())
+                    .map_err(Into::into)
+            }),
+        ));
+        Ok(Box::pin(
+            RecordBatchStreamAdapter::try_new(stream)
+                .map_err(BoxedError::new)
+                .context(InternalSnafu)?,
+        ))
+    }
+}
+
+/// Builds the `pg_catalog.pg_database` table row by row
+/// `oid` use schema name as a workaround since we don't have numeric schema id.
+/// `nspname` is the schema name.
+struct PGCDatabaseBuilder {
+    schema: SchemaRef,
+    catalog_name: String,
+    catalog_manager: Weak<dyn CatalogManager>,
+    namespace_oid_map: PGNamespaceOidMapRef,
+
+    oid: UInt32VectorBuilder,
+    datname: StringVectorBuilder,
+}
+
+impl PGCDatabaseBuilder {
+    fn new(
+        schema: SchemaRef,
+        catalog_name: String,
+        catalog_manager: Weak<dyn CatalogManager>,
+        namespace_oid_map: PGNamespaceOidMapRef,
+    ) -> Self {
+        Self {
+            schema,
+            catalog_name,
+            catalog_manager,
+            namespace_oid_map,
+
+            oid: UInt32VectorBuilder::with_capacity(INIT_CAPACITY),
+            datname: StringVectorBuilder::with_capacity(INIT_CAPACITY),
+        }
+    }
+
+    async fn make_database(&mut self, request: Option<ScanRequest>) -> Result<RecordBatch> {
+        let catalog_name = self.catalog_name.clone();
+        let catalog_manager = self
+            .catalog_manager
+            .upgrade()
+            .context(UpgradeWeakCatalogManagerRefSnafu)?;
+        let predicates = Predicates::from_scan_request(&request);
+        for schema_name in catalog_manager
+            .schema_names(&catalog_name, query_ctx())
+            .await?
+        {
+            self.add_database(&predicates, &schema_name);
+        }
+        self.finish()
+    }
+
+    fn add_database(&mut self, predicates: &Predicates, schema_name: &str) {
+        let oid = self.namespace_oid_map.get_oid(schema_name);
+        let row: [(&str, &Value); 2] = [
+            (OID_COLUMN_NAME, &Value::from(oid)),
+            (DATNAME, &Value::from(schema_name)),
+        ];
+
+        if !predicates.eval(&row) {
+            return;
+        }
+
+        self.oid.push(Some(oid));
+        self.datname.push(Some(schema_name));
+    }
+
+    fn finish(&mut self) -> Result<RecordBatch> {
+        let columns: Vec<VectorRef> =
+            vec![Arc::new(self.oid.finish()), Arc::new(self.datname.finish())];
+        RecordBatch::new(self.schema.clone(), columns).context(CreateRecordBatchSnafu)
+    }
+}

src/catalog/src/system_schema/pg_catalog/table_names.rs

@@ -12,7 +12,11 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-pub const PG_DATABASE: &str = "pg_databases";
+// https://www.postgresql.org/docs/current/catalog-pg-database.html
+pub const PG_DATABASE: &str = "pg_database";
+// https://www.postgresql.org/docs/current/catalog-pg-namespace.html
 pub const PG_NAMESPACE: &str = "pg_namespace";
+// https://www.postgresql.org/docs/current/catalog-pg-class.html
 pub const PG_CLASS: &str = "pg_class";
+// https://www.postgresql.org/docs/current/catalog-pg-type.html
 pub const PG_TYPE: &str = "pg_type";

src/common/catalog/src/consts.rs

@@ -109,6 +109,7 @@ pub const INFORMATION_SCHEMA_REGION_STATISTICS_TABLE_ID: u32 = 35;
 pub const PG_CATALOG_PG_CLASS_TABLE_ID: u32 = 256;
 pub const PG_CATALOG_PG_TYPE_TABLE_ID: u32 = 257;
 pub const PG_CATALOG_PG_NAMESPACE_TABLE_ID: u32 = 258;
+pub const PG_CATALOG_PG_DATABASE_TABLE_ID: u32 = 259;
 
 // ----- End of pg_catalog tables -----
 

src/servers/src/postgres/fixtures.rs

@@ -119,7 +119,15 @@ static LIMIT_CAST_PATTERN: Lazy<Regex> =
     Lazy::new(|| Regex::new("(?i)(LIMIT\\s+\\d+)::bigint").unwrap());
 pub(crate) fn rewrite_sql(query: &str) -> Cow<'_, str> {
     //TODO(sunng87): remove this when we upgraded datafusion to 43 or newer
-    LIMIT_CAST_PATTERN.replace_all(query, "$1")
+    let query = LIMIT_CAST_PATTERN.replace_all(query, "$1");
+    // DBeaver tricky replacement for datafusion not support sql
+    // TODO: add more here
+    query
+        .replace(
+            "SELECT db.oid,db.* FROM pg_catalog.pg_database db",
+            "SELECT db.oid as _oid,db.* FROM pg_catalog.pg_database db",
+        )
+        .into()
 }
 
 #[cfg(test)]
@@ -215,5 +223,9 @@ mod test {
 
         assert_eq!("SELECT * FROM number LIMIT 1", rewrite_sql(sql));
         assert_eq!("SELECT * FROM number limit      1", rewrite_sql(sql2));
+        assert_eq!(
+            "SELECT db.oid as _oid,db.* FROM pg_catalog.pg_database db",
+            rewrite_sql("SELECT db.oid,db.* FROM pg_catalog.pg_database db")
+        );
     }
 }

tests/cases/standalone/common/system/pg_catalog.result

@@ -74,6 +74,10 @@ select * from pg_catalog.pg_type;
 
 Error: 4001(TableNotFound), Failed to plan SQL: Table not found: greptime.pg_catalog.pg_type
 
+select * from pg_catalog.pg_database;
+
+Error: 4001(TableNotFound), Failed to plan SQL: Table not found: greptime.pg_catalog.pg_database
+
 -- SQLNESS PROTOCOL POSTGRES
 select * from pg_catalog.pg_type order by oid;
 
@@ -102,6 +106,15 @@ select * from pg_catalog.pg_type order by oid;
 | 20  | List      | -1     |
 +-----+-----------+--------+
 
+-- SQLNESS PROTOCOL POSTGRES
+select * from pg_catalog.pg_database where datname = 'public';
+
++------------+---------+
+| oid        | datname |
++------------+---------+
+| 3927743705 | public  |
++------------+---------+
+
 -- \d
 -- SQLNESS PROTOCOL POSTGRES
 SELECT n.nspname as "Schema",

tests/cases/standalone/common/system/pg_catalog.sql

@@ -28,10 +28,14 @@ select current_schema();
 select * from pg_catalog.pg_class;
 select * from pg_catalog.pg_namespace;
 select * from pg_catalog.pg_type;
+select * from pg_catalog.pg_database;
 
 -- SQLNESS PROTOCOL POSTGRES
 select * from pg_catalog.pg_type order by oid;
 
+-- SQLNESS PROTOCOL POSTGRES
+select * from pg_catalog.pg_database where datname = 'public';
+
 -- \d
 -- SQLNESS PROTOCOL POSTGRES
 SELECT n.nspname as "Schema",