diff --git a/crates/ra_db/src/lib.rs b/crates/ra_db/src/lib.rs
index 3a0aa7d246..4bfc3f9ae9 100644
--- a/crates/ra_db/src/lib.rs
+++ b/crates/ra_db/src/lib.rs
@@ -20,7 +20,7 @@ pub use crate::{
     loc2id::LocationIntener,
 };
 
-pub trait BaseDatabase: salsa::Database + panic::RefUnwindSafe {
+pub trait CheckCanceled: salsa::Database + panic::RefUnwindSafe {
     /// Aborts current query if there are pending changes.
     ///
     /// rust-analyzer needs to be able to answer semantic questions about the
@@ -64,10 +64,12 @@ pub struct FileRange {
 }
 
 #[salsa::query_group(FilesDatabaseStorage)]
-pub trait FilesDatabase: salsa::Database {
+pub trait FilesDatabase: salsa::Database + CheckCanceled {
     /// Text of the file.
     #[salsa::input]
     fn file_text(&self, file_id: FileId) -> Arc<String>;
+    // Parses the file into the syntax tree.
+    fn source_file(&self, file_id: FileId) -> TreeArc<SourceFile>;
     /// Path to a file, relative to the root of its source root.
     #[salsa::input]
     fn file_relative_path(&self, file_id: FileId) -> RelativePathBuf;
@@ -102,12 +104,7 @@ fn source_root_crates(db: &impl FilesDatabase, id: SourceRootId) -> Arc<Vec<Crat
     Arc::new(res)
 }
 
-#[salsa::query_group(SyntaxDatabaseStorage)]
-pub trait SyntaxDatabase: FilesDatabase + BaseDatabase {
-    fn source_file(&self, file_id: FileId) -> TreeArc<SourceFile>;
-}
-
-fn source_file(db: &impl SyntaxDatabase, file_id: FileId) -> TreeArc<SourceFile> {
+fn source_file(db: &impl FilesDatabase, file_id: FileId) -> TreeArc<SourceFile> {
     let text = db.file_text(file_id);
     SourceFile::parse(&*text)
 }
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index dfbf41bd66..1bb9e03056 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -1,7 +1,7 @@
 use std::sync::Arc;
 
 use ra_syntax::{SyntaxNode, TreeArc, SourceFile};
-use ra_db::{SyntaxDatabase, CrateId, salsa};
+use ra_db::{FilesDatabase, CrateId, salsa};
 
 use crate::{
     MacroCallId, HirFileId,
@@ -19,7 +19,7 @@ use crate::{
 };
 
 #[salsa::query_group(HirDatabaseStorage)]
-pub trait HirDatabase: SyntaxDatabase + AsRef<HirInterner> {
+pub trait HirDatabase: FilesDatabase + AsRef<HirInterner> {
     #[salsa::invoke(HirFileId::hir_source_file)]
     fn hir_source_file(&self, file_id: HirFileId) -> TreeArc<SourceFile>;
 
diff --git a/crates/ra_hir/src/mock.rs b/crates/ra_hir/src/mock.rs
index 2dc252b1ee..4af4dd096e 100644
--- a/crates/ra_hir/src/mock.rs
+++ b/crates/ra_hir/src/mock.rs
@@ -2,7 +2,7 @@ use std::{sync::Arc, panic};
 
 use parking_lot::Mutex;
 use ra_db::{
-    BaseDatabase, FilePosition, FileId, CrateGraph, SourceRoot, SourceRootId, FilesDatabase, salsa,
+    CheckCanceled, FilePosition, FileId, CrateGraph, SourceRoot, SourceRootId, FilesDatabase, salsa,
 };
 use relative_path::RelativePathBuf;
 use test_utils::{parse_fixture, CURSOR_MARKER, extract_offset};
@@ -11,11 +11,7 @@ use crate::{db, HirInterner};
 
 pub const WORKSPACE: SourceRootId = SourceRootId(0);
 
-#[salsa::database(
-    ra_db::FilesDatabaseStorage,
-    ra_db::SyntaxDatabaseStorage,
-    db::HirDatabaseStorage
-)]
+#[salsa::database(ra_db::FilesDatabaseStorage, db::HirDatabaseStorage)]
 #[derive(Debug)]
 pub(crate) struct MockDatabase {
     events: Mutex<Option<Vec<salsa::Event<MockDatabase>>>>,
@@ -161,7 +157,7 @@ impl salsa::ParallelDatabase for MockDatabase {
     }
 }
 
-impl BaseDatabase for MockDatabase {}
+impl CheckCanceled for MockDatabase {}
 
 impl AsRef<HirInterner> for MockDatabase {
     fn as_ref(&self) -> &HirInterner {
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index 389bdaf237..a56783b6e6 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -1,7 +1,7 @@
 use std::sync::Arc;
 use std::fmt::Write;
 
-use ra_db::{SyntaxDatabase, salsa::Database};
+use ra_db::{FilesDatabase, salsa::Database};
 use ra_syntax::ast::{self, AstNode};
 
 use crate::{
diff --git a/crates/ra_ide_api/src/call_info.rs b/crates/ra_ide_api/src/call_info.rs
index 0449c1902a..0eb70df162 100644
--- a/crates/ra_ide_api/src/call_info.rs
+++ b/crates/ra_ide_api/src/call_info.rs
@@ -1,4 +1,4 @@
-use ra_db::SyntaxDatabase;
+use ra_db::FilesDatabase;
 use ra_syntax::{
     AstNode, SyntaxNode, TextUnit, TextRange,
     SyntaxKind::FN_DEF,
diff --git a/crates/ra_ide_api/src/completion.rs b/crates/ra_ide_api/src/completion.rs
index 565d57c372..581ba5de81 100644
--- a/crates/ra_ide_api/src/completion.rs
+++ b/crates/ra_ide_api/src/completion.rs
@@ -9,7 +9,7 @@ mod complete_path;
 mod complete_scope;
 mod complete_postfix;
 
-use ra_db::SyntaxDatabase;
+use ra_db::FilesDatabase;
 
 use crate::{
     db,
diff --git a/crates/ra_ide_api/src/db.rs b/crates/ra_ide_api/src/db.rs
index 30891aed49..02e12437c3 100644
--- a/crates/ra_ide_api/src/db.rs
+++ b/crates/ra_ide_api/src/db.rs
@@ -1,7 +1,7 @@
 use std::sync::Arc;
 
 use ra_db::{
-    BaseDatabase, FileId, Canceled,
+    CheckCanceled, FileId, Canceled,
     salsa::{self, Database},
 };
 
@@ -9,7 +9,6 @@ use crate::{symbol_index, LineIndex};
 
 #[salsa::database(
     ra_db::FilesDatabaseStorage,
-    ra_db::SyntaxDatabaseStorage,
     LineIndexDatabaseStorage,
     symbol_index::SymbolsDatabaseStorage,
     hir::db::HirDatabaseStorage
@@ -54,7 +53,7 @@ impl salsa::ParallelDatabase for RootDatabase {
     }
 }
 
-impl BaseDatabase for RootDatabase {}
+impl CheckCanceled for RootDatabase {}
 
 impl AsRef<hir::HirInterner> for RootDatabase {
     fn as_ref(&self) -> &hir::HirInterner {
@@ -63,7 +62,7 @@ impl AsRef<hir::HirInterner> for RootDatabase {
 }
 
 #[salsa::query_group(LineIndexDatabaseStorage)]
-pub(crate) trait LineIndexDatabase: ra_db::FilesDatabase + BaseDatabase {
+pub(crate) trait LineIndexDatabase: ra_db::FilesDatabase + CheckCanceled {
     fn line_index(&self, file_id: FileId) -> Arc<LineIndex>;
 }
 
diff --git a/crates/ra_ide_api/src/extend_selection.rs b/crates/ra_ide_api/src/extend_selection.rs
index 718b4def55..bc19b0b9d9 100644
--- a/crates/ra_ide_api/src/extend_selection.rs
+++ b/crates/ra_ide_api/src/extend_selection.rs
@@ -1,4 +1,4 @@
-use ra_db::SyntaxDatabase;
+use ra_db::FilesDatabase;
 use ra_syntax::{
     SyntaxNode, AstNode, SourceFile,
     ast, algo::find_covering_node,
diff --git a/crates/ra_ide_api/src/goto_definition.rs b/crates/ra_ide_api/src/goto_definition.rs
index dc0c50918e..0e40e35cef 100644
--- a/crates/ra_ide_api/src/goto_definition.rs
+++ b/crates/ra_ide_api/src/goto_definition.rs
@@ -1,4 +1,4 @@
-use ra_db::{FileId, SyntaxDatabase};
+use ra_db::{FileId, FilesDatabase};
 use ra_syntax::{
     AstNode, ast,
     algo::find_node_at_offset,
diff --git a/crates/ra_ide_api/src/hover.rs b/crates/ra_ide_api/src/hover.rs
index 4d4bfbc4da..04f5a746e7 100644
--- a/crates/ra_ide_api/src/hover.rs
+++ b/crates/ra_ide_api/src/hover.rs
@@ -1,4 +1,4 @@
-use ra_db::{SyntaxDatabase};
+use ra_db::FilesDatabase;
 use ra_syntax::{
     AstNode, SyntaxNode, TreeArc, ast,
     algo::{find_covering_node, find_node_at_offset, find_leaf_at_offset, visit::{visitor, Visitor}},
diff --git a/crates/ra_ide_api/src/imp.rs b/crates/ra_ide_api/src/imp.rs
index bd9e3f1e3c..f2d41321dc 100644
--- a/crates/ra_ide_api/src/imp.rs
+++ b/crates/ra_ide_api/src/imp.rs
@@ -4,7 +4,7 @@ use hir::{
     self, Problem, source_binder
 };
 use ra_db::{
-    FilesDatabase, SourceRoot, SourceRootId, SyntaxDatabase,
+    FilesDatabase, SourceRoot, SourceRootId,
     salsa::{Database, SweepStrategy},
 };
 use ra_ide_api_light::{self, assists, LocalEdit, Severity};
diff --git a/crates/ra_ide_api/src/lib.rs b/crates/ra_ide_api/src/lib.rs
index ffd026b045..8380aa6c29 100644
--- a/crates/ra_ide_api/src/lib.rs
+++ b/crates/ra_ide_api/src/lib.rs
@@ -34,7 +34,7 @@ use std::{fmt, sync::Arc};
 use ra_syntax::{SourceFile, TreeArc, TextRange, TextUnit};
 use ra_text_edit::TextEdit;
 use ra_db::{
-    SyntaxDatabase, FilesDatabase, BaseDatabase,
+    FilesDatabase, CheckCanceled,
     salsa::{self, ParallelDatabase},
 };
 use rayon::prelude::*;
diff --git a/crates/ra_ide_api/src/rename.rs b/crates/ra_ide_api/src/rename.rs
index 5b767addd3..fe81609df9 100644
--- a/crates/ra_ide_api/src/rename.rs
+++ b/crates/ra_ide_api/src/rename.rs
@@ -17,7 +17,7 @@ use crate::{
     SourceChange,
     SourceFileEdit,
 };
-use ra_db::{FilesDatabase, SyntaxDatabase};
+use ra_db::FilesDatabase;
 use relative_path::RelativePath;
 
 pub(crate) fn rename(
diff --git a/crates/ra_ide_api/src/runnables.rs b/crates/ra_ide_api/src/runnables.rs
index 0f9f8deb32..e21724207a 100644
--- a/crates/ra_ide_api/src/runnables.rs
+++ b/crates/ra_ide_api/src/runnables.rs
@@ -3,7 +3,7 @@ use ra_syntax::{
     TextRange, SyntaxNode,
     ast::{self, AstNode, NameOwner, ModuleItemOwner},
 };
-use ra_db::SyntaxDatabase;
+use ra_db::FilesDatabase;
 
 use crate::{db::RootDatabase, FileId};
 
diff --git a/crates/ra_ide_api/src/syntax_highlighting.rs b/crates/ra_ide_api/src/syntax_highlighting.rs
index a4d3ad0058..cfa0257dd2 100644
--- a/crates/ra_ide_api/src/syntax_highlighting.rs
+++ b/crates/ra_ide_api/src/syntax_highlighting.rs
@@ -1,5 +1,5 @@
 use ra_syntax::{ast, AstNode,};
-use ra_db::SyntaxDatabase;
+use ra_db::FilesDatabase;
 
 use crate::{
     FileId, HighlightedRange,