satellite/metabase: add method to get table statistics

In loop we need to start verifying it's correctness. This allows to
gather these stats.

Change-Id: I146fb50e2b3658b6f3c2682cdc1983e6abd73c29

satellite/metabase/db.go

@@ -74,9 +74,8 @@ func Open(ctx context.Context, log *zap.Logger, connstr string) (*DB, error) {
 	return db, nil
 }
 
-// InternalImplementation returns *metabase.DB.
-// TODO: remove.
-func (db *DB) InternalImplementation() interface{} { return db }
+// Implementation rturns the database implementation.
+func (db *DB) Implementation() dbutil.Implementation { return db.impl }
 
 // UnderlyingTagSQL returns *tagsql.DB.
 // TODO: remove.

satellite/metabase/metabasetest/run.go

@@ -37,7 +37,7 @@ func Run(t *testing.T, fn func(ctx *testcontext.Context, t *testing.T, db *metab
 				t.Fatal(err)
 			}
 
-			fn(ctx, t, db.InternalImplementation().(*metabase.DB))
+			fn(ctx, t, db)
 		})
 	}
 }
@@ -65,7 +65,7 @@ func Bench(b *testing.B, fn func(ctx *testcontext.Context, b *testing.B, db *met
 			}
 
 			b.ResetTimer()
-			fn(ctx, b, db.InternalImplementation().(*metabase.DB))
+			fn(ctx, b, db)
 		})
 	}
 }

satellite/metabase/metabasetest/test.go

@@ -721,3 +721,22 @@ func (step DeletePart) Check(ctx *testcontext.Context, t testing.TB, db *metabas
 	diff := cmp.Diff(step.Result, result, cmpopts.EquateApproxTime(5*time.Second))
 	require.Zero(t, diff)
 }
+
+// GetTableStats is for testing metabase.GetTableStats.
+type GetTableStats struct {
+	Opts     metabase.GetTableStats
+	Result   metabase.TableStats
+	ErrClass *errs.Class
+	ErrText  string
+}
+
+// Check runs the test.
+func (step GetTableStats) Check(ctx *testcontext.Context, t testing.TB, db *metabase.DB) metabase.TableStats {
+	result, err := db.GetTableStats(ctx, step.Opts)
+	checkError(t, err, step.ErrClass, step.ErrText)
+
+	diff := cmp.Diff(step.Result, result)
+	require.Zero(t, diff)
+
+	return result
+}

satellite/metabase/stats.go

@@ -0,0 +1,41 @@
+// Copyright (C) 2021 Storj Labs, Inc.
+// See LICENSE for copying information.
+
+package metabase
+
+import (
+	"context"
+	"time"
+
+	"github.com/zeebo/errs"
+
+	"storj.io/common/errs2"
+)
+
+// GetTableStats contains arguments necessary for getting table statistics.
+type GetTableStats struct {
+	AsOfSystemInterval time.Duration
+}
+
+// TableStats contains information about the metabase status.
+type TableStats struct {
+	ObjectCount  int64
+	SegmentCount int64
+}
+
+// GetTableStats gathers information about the metabase tables.
+func (db *DB) GetTableStats(ctx context.Context, opts GetTableStats) (result TableStats, err error) {
+	defer mon.Task()(&ctx)(&err)
+
+	var group errs2.Group
+	group.Go(func() error {
+		row := db.db.QueryRow(ctx, `SELECT count(*) FROM objects `+db.impl.AsOfSystemInterval(opts.AsOfSystemInterval))
+		return Error.Wrap(row.Scan(&result.ObjectCount))
+	})
+	group.Go(func() error {
+		row := db.db.QueryRow(ctx, `SELECT count(*) FROM segments `+db.impl.AsOfSystemInterval(opts.AsOfSystemInterval))
+		return Error.Wrap(row.Scan(&result.SegmentCount))
+	})
+	err = errs.Combine(group.Wait()...)
+	return result, err
+}

satellite/metabase/stats_test.go

@@ -0,0 +1,93 @@
+// Copyright (C) 2021 Storj Labs, Inc.
+// See LICENSE for copying information.
+
+package metabase_test
+
+import (
+	"testing"
+	"time"
+
+	"storj.io/common/testcontext"
+	"storj.io/private/dbutil"
+	"storj.io/storj/satellite/metabase"
+	"storj.io/storj/satellite/metabase/metabasetest"
+)
+
+func TestGetTableStats(t *testing.T) {
+	metabasetest.Run(t, func(ctx *testcontext.Context, t *testing.T, db *metabase.DB) {
+		t.Run("no data", func(t *testing.T) {
+			defer metabasetest.DeleteAll{}.Check(ctx, t, db)
+
+			metabasetest.GetTableStats{
+				Result: metabase.TableStats{},
+			}.Check(ctx, t, db)
+
+			metabasetest.Verify{}.Check(ctx, t, db)
+		})
+
+		t.Run("data", func(t *testing.T) {
+			defer metabasetest.DeleteAll{}.Check(ctx, t, db)
+
+			obj1 := metabasetest.RandObjectStream()
+			metabasetest.CreateTestObject{}.Run(ctx, t, db, obj1, 4)
+
+			metabasetest.GetTableStats{
+				Result: metabase.TableStats{
+					ObjectCount:  1,
+					SegmentCount: 4,
+				},
+			}.Check(ctx, t, db)
+
+			obj2 := metabasetest.RandObjectStream()
+			metabasetest.CreateTestObject{}.Run(ctx, t, db, obj2, 3)
+
+			metabasetest.GetTableStats{
+				Result: metabase.TableStats{
+					ObjectCount:  2,
+					SegmentCount: 7,
+				},
+			}.Check(ctx, t, db)
+		})
+
+		if db.Implementation() == dbutil.Cockroach {
+			t.Run("as of interval", func(t *testing.T) {
+				defer metabasetest.DeleteAll{}.Check(ctx, t, db)
+
+				metabasetest.GetTableStats{
+					Opts: metabase.GetTableStats{
+						AsOfSystemInterval: -time.Microsecond,
+					},
+					Result: metabase.TableStats{
+						ObjectCount:  0,
+						SegmentCount: 0,
+					},
+				}.Check(ctx, t, db)
+
+				time.Sleep(2 * time.Second)
+
+				obj1 := metabasetest.RandObjectStream()
+				metabasetest.CreateTestObject{}.Run(ctx, t, db, obj1, 4)
+
+				metabasetest.GetTableStats{
+					Opts: metabase.GetTableStats{
+						AsOfSystemInterval: -1 * time.Second,
+					},
+					Result: metabase.TableStats{
+						ObjectCount:  0,
+						SegmentCount: 0,
+					},
+				}.Check(ctx, t, db)
+
+				metabasetest.GetTableStats{
+					Opts: metabase.GetTableStats{
+						AsOfSystemInterval: -time.Microsecond,
+					},
+					Result: metabase.TableStats{
+						ObjectCount:  1,
+						SegmentCount: 4,
+					},
+				}.Check(ctx, t, db)
+			})
+		}
+	})
+}