internal/postgres: delete Legacy functions

For golang/go#37102

Change-Id: Icda2856dd6af29267affd075a95974a3c65c0adc
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/317429
Trust: Julie Qiu <julie@golang.org>
Run-TryBot: Julie Qiu <julie@golang.org>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

5 files changed, 68 insertions, 307 deletions

diff --git a/internal/postgres/insert_symbol_history.go b/internal/postgres/insert_symbol_history.go
index 19b41e2d..ba55bc4b 100644
--- a/internal/postgres/insert_symbol_history.go
+++ b/internal/postgres/insert_symbol_history.go
@@ -37,7 +37,7 @@ func upsertSymbolHistory(ctx context.Context, ddb *database.DB,
 		return err
 	}
 	for packagePath, docIDToDoc := range pathToDocIDToDoc {
-		dbVersionToNameToUnitSymbol, err := LegacyGetSymbolHistoryFromTable(ctx, ddb, packagePath, modulePath)
+		sh, err := GetSymbolHistoryFromTable(ctx, ddb, packagePath, modulePath)
 		if err != nil {
 			return err
 		}
@@ -49,10 +49,13 @@ func upsertSymbolHistory(ctx context.Context, ddb *database.DB,
 			}
 			for _, b := range builds {
 				dbNameToVersion := map[string]string{}
-				for v, nameToUS := range dbVersionToNameToUnitSymbol {
-					for name, us := range nameToUS {
-						if us.SupportsBuild(b) {
-							dbNameToVersion[name] = v
+				for _, v := range sh.Versions() {
+					nts := sh.SymbolsAtVersion(v)
+					for name, stu := range nts {
+						for _, us := range stu {
+							if us.SupportsBuild(b) {
+								dbNameToVersion[name] = v
+							}
 						}
 					}
 				}
diff --git a/internal/postgres/package_symbol.go b/internal/postgres/package_symbol.go
index 6cb34777..fcebeb3d 100644
--- a/internal/postgres/package_symbol.go
+++ b/internal/postgres/package_symbol.go
@@ -50,7 +50,10 @@ func getPackageSymbols(ctx context.Context, ddb *database.DB, packagePath, modul
 	sh, collect := collectSymbolHistory(func(sh *internal.SymbolHistory, sm internal.SymbolMeta, v string, build internal.BuildContext) error {
 		if sm.Section == internal.SymbolSectionTypes && sm.Kind != internal.SymbolKindType {
 			_, err := sh.GetSymbol(sm.ParentName, v, build)
-			return err
+			if err != nil {
+				return fmt.Errorf("could not find parent for %q: %v", sm.Name, err)
+			}
+			return nil
 		}
 		return nil
 	})
@@ -88,99 +91,3 @@ func collectSymbolHistory(check func(sh *internal.SymbolHistory, sm internal.Sym
 		return nil
 	}
 }
-
-// legacyGetPackageSymbols returns all of the symbols for a given package path and module path.
-func legacyGetPackageSymbols(ctx context.Context, ddb *database.DB, packagePath, modulePath string,
-) (_ map[string]map[string]*internal.UnitSymbol, err error) {
-	defer derrors.Wrap(&err, "legacyGetPackageSymbols(ctx, ddb, %q, %q)", packagePath, modulePath)
-	defer middleware.ElapsedStat(ctx, "getPackageSymbols")()
-	query := `
-		SELECT
-			s1.name AS symbol_name,
-			s2.name AS parent_symbol_name,
-			ps.section,
-			ps.type,
-			ps.synopsis,
-			m.version,
-			d.goos,
-			d.goarch
-		FROM modules m
-		INNER JOIN units u ON u.module_id = m.id
-		INNER JOIN documentation d ON d.unit_id = u.id
-		INNER JOIN documentation_symbols ds ON ds.documentation_id = d.id
-		INNER JOIN package_symbols ps ON ps.id = ds.package_symbol_id
-		INNER JOIN paths p1 ON u.path_id = p1.id
-		INNER JOIN symbol_names s1 ON ps.symbol_name_id = s1.id
-		INNER JOIN symbol_names s2 ON ps.parent_symbol_name_id = s2.id
-		WHERE
-			p1.path = $1
-			AND m.module_path = $2
-			AND NOT m.incompatible
-			AND m.version_type = 'release'
-		ORDER BY
-			CASE WHEN ps.type='Type' THEN 0 ELSE 1 END,
-			symbol_name;`
-
-	// versionToNameToUnitSymbol contains all of the types for this unit,
-	// grouped by name and build context. This is used to keep track of the
-	// parent types, so that we can map the children to those symbols.
-	versionToNameToUnitSymbol := map[string]map[string]*internal.UnitSymbol{}
-	collect := func(rows *sql.Rows) error {
-		var (
-			newUS internal.UnitSymbol
-			build internal.BuildContext
-			v     string
-		)
-		if err := rows.Scan(
-			&newUS.Name,
-			&newUS.ParentName,
-			&newUS.Section,
-			&newUS.Kind,
-			&newUS.Synopsis,
-			&v,
-			&build.GOOS,
-			&build.GOARCH,
-		); err != nil {
-			return fmt.Errorf("row.Scan(): %v", err)
-		}
-		if newUS.Section == internal.SymbolSectionTypes && newUS.Kind != internal.SymbolKindType {
-			if err := validateChildSymbol(&newUS, v, build, versionToNameToUnitSymbol); err != nil {
-				return err
-			}
-		}
-		nts, ok := versionToNameToUnitSymbol[v]
-		if !ok {
-			nts = map[string]*internal.UnitSymbol{}
-			versionToNameToUnitSymbol[v] = nts
-		}
-		us, ok := nts[newUS.Name]
-		if !ok {
-			us = &newUS
-			nts[newUS.Name] = us
-		}
-		us.AddBuildContext(build)
-		return nil
-	}
-	if err := ddb.RunQuery(ctx, query, collect, packagePath, modulePath); err != nil {
-		return nil, err
-	}
-	return versionToNameToUnitSymbol, nil
-}
-
-func validateChildSymbol(us *internal.UnitSymbol, v string, build internal.BuildContext,
-	versionToNameToUnitSymbol map[string]map[string]*internal.UnitSymbol) error {
-	nameToUnitSymbol, ok := versionToNameToUnitSymbol[v]
-	if !ok {
-		return fmt.Errorf("version %q could not be found: %q", v, us.Name)
-	}
-	parent, ok := nameToUnitSymbol[us.ParentName]
-	if !ok {
-		return fmt.Errorf("parent %q could not be found at version %q: %q",
-			us.ParentName, v, us.Name)
-	}
-	if !parent.SupportsBuild(build) {
-		return fmt.Errorf("parent %q does not have build %v at version %q: %q",
-			us.ParentName, build, v, us.Name)
-	}
-	return nil
-}
diff --git a/internal/postgres/symbol_history.go b/internal/postgres/symbol_history.go
index 81d0bc0e..252bceeb 100644
--- a/internal/postgres/symbol_history.go
+++ b/internal/postgres/symbol_history.go
@@ -87,106 +87,6 @@ func GetSymbolHistoryWithPackageSymbols(ctx context.Context, ddb *database.DB,
 	return symbol.IntroducedHistory(sh)
 }
 
-// LegacyGetSymbolHistory returns a map of the first version when a symbol name is
-// added to the API, to the symbol name, to the UnitSymbol struct. The
-// UnitSymbol.Children field will always be empty, as children names are also
-// tracked.
-func (db *DB) LegacyGetSymbolHistory(ctx context.Context, packagePath, modulePath string,
-) (_ map[string]map[string]*internal.UnitSymbol, err error) {
-	defer derrors.Wrap(&err, "LegacyGetSymbolHistory(ctx, %q, %q)", packagePath, modulePath)
-	defer middleware.ElapsedStat(ctx, "LegacyGetSymbolHistory")()
-
-	if experiment.IsActive(ctx, internal.ExperimentReadSymbolHistory) {
-		return LegacyGetSymbolHistoryFromTable(ctx, db.db, packagePath, modulePath)
-	}
-	return LegacyGetSymbolHistoryWithPackageSymbols(ctx, db.db, packagePath, modulePath)
-}
-
-// LegacyGetSymbolHistoryFromTable fetches symbol history data from the symbol_history table.
-//
-// LegacyGetSymbolHistoryFromTable is exported for use in tests.
-func LegacyGetSymbolHistoryFromTable(ctx context.Context, ddb *database.DB,
-	packagePath, modulePath string) (_ map[string]map[string]*internal.UnitSymbol, err error) {
-	defer derrors.WrapStack(&err, "LegacyGetSymbolHistoryFromTable(ctx, ddb, %q, %q)", packagePath, modulePath)
-
-	q := squirrel.Select(
-		"s1.name AS symbol_name",
-		"s2.name AS parent_symbol_name",
-		"ps.section",
-		"ps.type",
-		"ps.synopsis",
-		"sh.since_version",
-		"sh.goos",
-		"sh.goarch",
-	).From("symbol_history sh").
-		Join("package_symbols ps ON ps.id = sh.package_symbol_id").
-		Join("symbol_names s1 ON ps.symbol_name_id = s1.id").
-		Join("symbol_names s2 ON ps.parent_symbol_name_id = s2.id").
-		Join("paths p1 ON sh.package_path_id = p1.id").
-		Join("paths p2 ON sh.module_path_id = p2.id").
-		Where(squirrel.Eq{"p1.path": packagePath}).
-		Where(squirrel.Eq{"p2.path": modulePath})
-	query, args, err := q.PlaceholderFormat(squirrel.Dollar).ToSql()
-	if err != nil {
-		return nil, err
-	}
-
-	// versionToNameToUnitSymbol is a map of the version a symbol was
-	// introduced, to the name and unit symbol.
-	versionToNameToUnitSymbol := map[string]map[string]*internal.UnitSymbol{}
-	collect := func(rows *sql.Rows) error {
-		var (
-			newUS internal.UnitSymbol
-			build internal.BuildContext
-			v     string
-		)
-		if err := rows.Scan(
-			&newUS.Name,
-			&newUS.ParentName,
-			&newUS.Section,
-			&newUS.Kind,
-			&newUS.Synopsis,
-			&v,
-			&build.GOOS,
-			&build.GOARCH,
-		); err != nil {
-			return fmt.Errorf("row.Scan(): %v", err)
-		}
-		nts, ok := versionToNameToUnitSymbol[v]
-		if !ok {
-			nts = map[string]*internal.UnitSymbol{}
-			versionToNameToUnitSymbol[v] = nts
-		}
-		us, ok := nts[newUS.Name]
-		if !ok {
-			us = &newUS
-			nts[newUS.Name] = us
-		}
-		us.AddBuildContext(build)
-		return nil
-	}
-	if err := ddb.RunQuery(ctx, query, collect, args...); err != nil {
-		return nil, err
-	}
-	return versionToNameToUnitSymbol, nil
-}
-
-// LegacyGetSymbolHistoryWithPackageSymbols fetches symbol history data by using data
-// from package_symbols and documentation_symbols, and computed using
-// symbol.IntroducedHistory.
-//
-// LegacyGetSymbolHistoryWithPackageSymbols is exported for use in tests.
-func LegacyGetSymbolHistoryWithPackageSymbols(ctx context.Context, ddb *database.DB,
-	packagePath, modulePath string) (_ map[string]map[string]*internal.UnitSymbol, err error) {
-	defer derrors.WrapStack(&err, "GetSymbolHistoryWithPackageSymbols(ctx, ddb, %q, %q)", packagePath, modulePath)
-	defer middleware.ElapsedStat(ctx, "GetSymbolHistoryWithPackageSymbols")()
-	versionToNameToUnitSymbols, err := legacyGetPackageSymbols(ctx, ddb, packagePath, modulePath)
-	if err != nil {
-		return nil, err
-	}
-	return symbol.LegacyIntroducedHistory(versionToNameToUnitSymbols), nil
-}
-
 // GetSymbolHistoryForBuildContext returns a map of the first version when a symbol name is
 // added to the API for the specified build context, to the symbol name, to the
 // UnitSymbol struct. The UnitSymbol.Children field will always be empty, as
diff --git a/internal/postgres/symbol_test.go b/internal/postgres/symbol_test.go
index 84cba912..4193b6f2 100644
--- a/internal/postgres/symbol_test.go
+++ b/internal/postgres/symbol_test.go
@@ -63,27 +63,23 @@ func TestInsertSymbolNamesAndHistory(t *testing.T) {
 	}
 	compareUnitSymbols(ctx, t, testDB, mod.Packages()[0].Path, mod.ModulePath, mod.Version,
 		map[internal.BuildContext][]*internal.Symbol{internal.BuildContextAll: api})
-	want2 := map[string]map[string]*internal.UnitSymbol{}
-	want2[mod.Version] = unitSymbolsFromAPI(api, mod.Version)
+	want2 := symbolHistoryFromAPI(api, mod.Version)
 	comparePackageSymbols(ctx, t, testDB, mod.Packages()[0].Path, mod.ModulePath, mod.Version, want2)
 
-	gotHist, err := testDB.LegacyGetSymbolHistory(ctx, mod.Packages()[0].Path, mod.ModulePath)
+	gotHist, err := testDB.GetSymbolHistory(ctx, mod.Packages()[0].Path, mod.ModulePath)
 	if err != nil {
 		t.Fatal(err)
 	}
-	wantHist := map[string]map[string]*internal.UnitSymbol{
-		"v1.0.0": map[string]*internal.UnitSymbol{
-			"Constant":    unitSymbolFromSymbol(sample.Constant, "v1.0.0"),
-			"Variable":    unitSymbolFromSymbol(sample.Variable, "v1.0.0"),
-			"Function":    unitSymbolFromSymbol(sample.Function, "v1.0.0"),
-			"Type":        unitSymbolFromSymbol(sample.Type, "v1.0.0"),
-			"Type.Field":  unitSymbolFromSymbolMeta(sample.Type.Children[0], "v1.0.0", internal.BuildContextAll),
-			"New":         unitSymbolFromSymbolMeta(sample.Type.Children[1], "v1.0.0", internal.BuildContextAll),
-			"Type.Method": unitSymbolFromSymbolMeta(sample.Type.Children[2], "v1.0.0", internal.BuildContextAll),
-		},
-	}
+	wantHist := internal.NewSymbolHistory()
+	wantHist.AddSymbol(sample.Constant.SymbolMeta, "v1.0.0", internal.BuildContextAll)
+	wantHist.AddSymbol(sample.Variable.SymbolMeta, "v1.0.0", internal.BuildContextAll)
+	wantHist.AddSymbol(sample.Function.SymbolMeta, "v1.0.0", internal.BuildContextAll)
+	wantHist.AddSymbol(sample.Type.SymbolMeta, "v1.0.0", internal.BuildContextAll)
+	wantHist.AddSymbol(*sample.Type.Children[0], "v1.0.0", internal.BuildContextAll)
+	wantHist.AddSymbol(*sample.Type.Children[1], "v1.0.0", internal.BuildContextAll)
+	wantHist.AddSymbol(*sample.Type.Children[2], "v1.0.0", internal.BuildContextAll)
 	if diff := cmp.Diff(wantHist, gotHist,
-		cmp.AllowUnexported(internal.UnitSymbol{})); diff != "" {
+		cmp.AllowUnexported(internal.UnitSymbol{}, internal.SymbolHistory{})); diff != "" {
 		t.Fatalf("mismatch on symbol history(-want +got):\n%s", diff)
 	}
 }
@@ -116,8 +112,7 @@ func TestInsertSymbolHistory_Basic(t *testing.T) {
 
 	compareUnitSymbols(ctx, t, testDB, mod.Packages()[0].Path, mod.ModulePath, mod.Version,
 		map[internal.BuildContext][]*internal.Symbol{internal.BuildContextAll: api})
-	want2 := map[string]map[string]*internal.UnitSymbol{}
-	want2[mod.Version] = unitSymbolsFromAPI(api, mod.Version)
+	want2 := symbolHistoryFromAPI(api, mod.Version)
 	comparePackageSymbols(ctx, t, testDB, mod.Packages()[0].Path, mod.ModulePath, mod.Version, want2)
 }
 
@@ -187,7 +182,7 @@ func TestInsertSymbolHistory_MultiVersions(t *testing.T) {
 	compareUnitSymbols(ctx, t, testDB, mod11.Packages()[0].Path, mod11.ModulePath, mod11.Version, want11)
 	compareUnitSymbols(ctx, t, testDB, mod12.Packages()[0].Path, mod12.ModulePath, mod12.Version, want12)
 
-	want2 := map[string]map[string]*internal.UnitSymbol{}
+	want2 := internal.NewSymbolHistory()
 	for _, want := range []struct {
 		version        string
 		buildToSymbols map[internal.BuildContext][]*internal.Symbol
@@ -196,13 +191,16 @@ func TestInsertSymbolHistory_MultiVersions(t *testing.T) {
 		{mod11.Version, want11},
 		{mod12.Version, want12},
 	} {
-		for _, api := range want.buildToSymbols {
-			want2[want.version] = unitSymbolsFromAPI(api, want.version)
+		for build, api := range want.buildToSymbols {
+			updateSymbols(api, func(s *internal.SymbolMeta) error {
+				want2.AddSymbol(*s, want.version, build)
+				return nil
+			})
 		}
 	}
 	comparePackageSymbols(ctx, t, testDB, mod10.Packages()[0].Path, mod10.ModulePath, mod10.Version, want2)
 
-	gotHist, err := testDB.LegacyGetSymbolHistory(ctx, mod10.Packages()[0].Path, mod10.ModulePath)
+	gotHist, err := testDB.GetSymbolHistory(ctx, mod10.Packages()[0].Path, mod10.ModulePath)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -212,19 +210,12 @@ func TestInsertSymbolHistory_MultiVersions(t *testing.T) {
 	typA.GOARCH = internal.All
 	methodA.GOARCH = internal.All
 	methodB.GOARCH = internal.All
-	wantHist := map[string]map[string]*internal.UnitSymbol{
-		"v1.0.0": map[string]*internal.UnitSymbol{
-			"Foo": unitSymbolFromSymbol(&typA, "v1.0.0"),
-		},
-		"v1.1.0": {
-			"Foo.A": unitSymbolFromSymbol(&methodA, "v1.1.0"),
-		},
-		"v1.2.0": {
-			"Foo.B": unitSymbolFromSymbol(&methodB, "v1.2.0"),
-		},
-	}
+	wantHist := internal.NewSymbolHistory()
+	wantHist.AddSymbol(typA.SymbolMeta, "v1.0.0", internal.BuildContextAll)
+	wantHist.AddSymbol(methodA.SymbolMeta, "v1.1.0", internal.BuildContextAll)
+	wantHist.AddSymbol(methodB.SymbolMeta, "v1.2.0", internal.BuildContextAll)
 	if diff := cmp.Diff(wantHist, gotHist,
-		cmp.AllowUnexported(internal.UnitSymbol{})); diff != "" {
+		cmp.AllowUnexported(internal.UnitSymbol{}, internal.SymbolHistory{})); diff != "" {
 		t.Fatalf("mismatch on symbol history(-want +got):\n%s", diff)
 	}
 }
@@ -339,15 +330,19 @@ func TestInsertSymbolHistory_MultiGOOS(t *testing.T) {
 	compareUnitSymbols(ctx, t, testDB, mod11.Packages()[0].Path, mod11.ModulePath, mod11.Version, want11)
 	compareUnitSymbols(ctx, t, testDB, mod12.Packages()[0].Path, mod12.ModulePath, mod12.Version, want12)
 
-	want2 := map[string]map[string]*internal.UnitSymbol{}
+	want2 := internal.NewSymbolHistory()
 	for _, mod := range []*internal.Module{mod10, mod11, mod12} {
-		want2[mod.Version] = map[string]*internal.UnitSymbol{}
 		for _, pkg := range mod.Packages() {
 			for _, doc := range pkg.Documentation {
-				nameToUnitSym := unitSymbolsFromAPI(doc.API, mod.Version)
-				for name, unitSym := range nameToUnitSym {
-					if _, ok := want2[mod.Version][name]; !ok {
-						want2[mod.Version][name] = unitSym
+				sh := symbolHistoryFromAPI(doc.API, mod.Version)
+				for _, v := range sh.Versions() {
+					nts := sh.SymbolsAtVersion(v)
+					for _, stu := range nts {
+						for sm, us := range stu {
+							for _, b := range us.BuildContexts() {
+								want2.AddSymbol(sm, mod.Version, b)
+							}
+						}
 					}
 				}
 			}
@@ -355,52 +350,25 @@ func TestInsertSymbolHistory_MultiGOOS(t *testing.T) {
 	}
 	comparePackageSymbols(ctx, t, testDB, mod10.Packages()[0].Path, mod10.ModulePath, mod10.Version, want2)
 
-	gotHist, err := testDB.LegacyGetSymbolHistory(ctx, mod10.Packages()[0].Path, mod10.ModulePath)
+	gotHist, err := testDB.GetSymbolHistory(ctx, mod10.Packages()[0].Path, mod10.ModulePath)
 	if err != nil {
 		t.Fatal(err)
 	}
 
 	typ.GOOS = internal.All
 	typ.GOARCH = internal.All
-	wantHist := map[string]map[string]*internal.UnitSymbol{
-		"v1.0.0": map[string]*internal.UnitSymbol{
-			"Foo": unitSymbolFromSymbol(&typ, "v1.0.0"),
-		},
-		"v1.1.0": map[string]*internal.UnitSymbol{
-			"Foo.A": func() *internal.UnitSymbol {
-				us := unitSymbolFromSymbol(&methodA, "v1.1.0")
-				us.RemoveBuildContexts()
-				us.AddBuildContext(internal.BuildContextLinux)
-				us.AddBuildContext(internal.BuildContextWindows)
-				return us
-			}(),
-			"Foo.B": func() *internal.UnitSymbol {
-				us := unitSymbolFromSymbol(&methodB, "v1.1.0")
-				us.RemoveBuildContexts()
-				us.AddBuildContext(internal.BuildContextJS)
-				us.AddBuildContext(internal.BuildContextDarwin)
-				return us
-			}(),
-		},
-		"v1.2.0": map[string]*internal.UnitSymbol{
-			"Foo.A": func() *internal.UnitSymbol {
-				us := unitSymbolFromSymbol(&methodA, "v1.2.0")
-				us.RemoveBuildContexts()
-				us.AddBuildContext(internal.BuildContextJS)
-				us.AddBuildContext(internal.BuildContextDarwin)
-				return us
-			}(),
-			"Foo.B": func() *internal.UnitSymbol {
-				us := unitSymbolFromSymbol(&methodB, "v1.2.0")
-				us.RemoveBuildContexts()
-				us.AddBuildContext(internal.BuildContextLinux)
-				us.AddBuildContext(internal.BuildContextWindows)
-				return us
-			}(),
-		},
-	}
+	wantHist := internal.NewSymbolHistory()
+	wantHist.AddSymbol(typ.SymbolMeta, "v1.0.0", internal.BuildContextAll)
+	wantHist.AddSymbol(methodA.SymbolMeta, "v1.1.0", internal.BuildContextLinux)
+	wantHist.AddSymbol(methodA.SymbolMeta, "v1.1.0", internal.BuildContextWindows)
+	wantHist.AddSymbol(methodB.SymbolMeta, "v1.1.0", internal.BuildContextJS)
+	wantHist.AddSymbol(methodB.SymbolMeta, "v1.1.0", internal.BuildContextDarwin)
+	wantHist.AddSymbol(methodA.SymbolMeta, "v1.2.0", internal.BuildContextJS)
+	wantHist.AddSymbol(methodA.SymbolMeta, "v1.2.0", internal.BuildContextDarwin)
+	wantHist.AddSymbol(methodB.SymbolMeta, "v1.2.0", internal.BuildContextLinux)
+	wantHist.AddSymbol(methodB.SymbolMeta, "v1.2.0", internal.BuildContextWindows)
 	if diff := cmp.Diff(wantHist, gotHist,
-		cmp.AllowUnexported(internal.UnitSymbol{})); diff != "" {
+		cmp.AllowUnexported(internal.UnitSymbol{}, internal.SymbolHistory{})); diff != "" {
 		t.Fatalf("mismatch on symbol history(-want +got):\n%s", diff)
 	}
 
@@ -473,42 +441,24 @@ func compareUnitSymbols(ctx context.Context, t *testing.T, testDB *DB,
 }
 
 func comparePackageSymbols(ctx context.Context, t *testing.T, testDB *DB,
-	path, modulePath, version string, want map[string]map[string]*internal.UnitSymbol) {
+	path, modulePath, version string, want *internal.SymbolHistory) {
 	t.Helper()
-	got, err := legacyGetPackageSymbols(ctx, testDB.db, path, modulePath)
+	got, err := getPackageSymbols(ctx, testDB.db, path, modulePath)
 	if err != nil {
 		t.Fatal(err)
 	}
 	if diff := cmp.Diff(want, got,
+		cmp.AllowUnexported(internal.UnitSymbol{}, internal.SymbolHistory{}),
 		cmpopts.IgnoreFields(internal.UnitSymbol{}, "builds")); diff != "" {
 		t.Errorf("mismatch (-want +got):\n%s", diff)
 	}
 }
 
-func unitSymbolsFromAPI(api []*internal.Symbol, version string) map[string]*internal.UnitSymbol {
-	nameToUnitSymbols := map[string]*internal.UnitSymbol{}
+func symbolHistoryFromAPI(api []*internal.Symbol, version string) *internal.SymbolHistory {
+	sh := internal.NewSymbolHistory()
 	updateSymbols(api, func(s *internal.SymbolMeta) error {
-		if _, ok := nameToUnitSymbols[s.Name]; !ok {
-			us := unitSymbolFromSymbolMeta(s, version, internal.BuildContextAll)
-			nameToUnitSymbols[s.Name] = us
-		}
+		sh.AddSymbol(*s, version, internal.BuildContextAll)
 		return nil
 	})
-	return nameToUnitSymbols
-}
-
-func unitSymbolFromSymbol(s *internal.Symbol, version string) *internal.UnitSymbol {
-	us := &internal.UnitSymbol{
-		SymbolMeta: s.SymbolMeta,
-	}
-	us.AddBuildContext(internal.BuildContext{GOOS: s.GOOS, GOARCH: s.GOARCH})
-	return us
-}
-
-func unitSymbolFromSymbolMeta(sm *internal.SymbolMeta, version string, b internal.BuildContext) *internal.UnitSymbol {
-	us := &internal.UnitSymbol{
-		SymbolMeta: *sm,
-	}
-	us.AddBuildContext(b)
-	return us
+	return sh
 }
diff --git a/internal/postgres/unit.go b/internal/postgres/unit.go
index 33da003a..72efd278 100644
--- a/internal/postgres/unit.go
+++ b/internal/postgres/unit.go
@@ -540,13 +540,14 @@ func (db *DB) getUnitWithAllFields(ctx context.Context, um *internal.UnitMeta, b
 			}
 			return &u, nil
 		}
-		versionToNameToUnitSymbol, err := LegacyGetSymbolHistoryWithPackageSymbols(ctx, db.db, um.Path,
+		sh, err := GetSymbolHistoryWithPackageSymbols(ctx, db.db, um.Path,
 			um.ModulePath)
 		if err != nil {
 			return nil, err
 		}
 		nameToVersion := map[string]string{}
-		for v, nts := range versionToNameToUnitSymbol {
+		for _, v := range sh.Versions() {
+			nts := sh.SymbolsAtVersion(v)
 			for n := range nts {
 				nameToVersion[n] = v
 			}