Return not found for non-existent DB refs

go/libraries/doltcore/sqle/database_provider.go

@@ -16,11 +16,13 @@ package sqle
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"sort"
 	"strings"
 	"sync"
 
+	"github.com/dolthub/dolt/go/store/datas"
 	"github.com/dolthub/go-mysql-server/sql"
 
 	"github.com/dolthub/dolt/go/cmd/dolt/cli"
@@ -794,6 +796,7 @@ func (p DoltDatabaseProvider) databaseForRevision(ctx *sql.Context, revisionQual
 		if !ok {
 			return nil, false, nil
 		}
+		
 		db, err := revisionDbForCommit(ctx, srcDb.(Database), rev, requestedName)
 		if err != nil {
 			return nil, false, err
@@ -814,12 +817,12 @@ func (p DoltDatabaseProvider) databaseForRevision(ctx *sql.Context, revisionQual
 func revisionDbType(ctx *sql.Context, srcDb dsess.SqlDatabase, revSpec string) (revType dsess.RevisionType, resolvedRevSpec string, err error) {
 	resolvedRevSpec, err = resolveAncestorSpec(ctx, revSpec, srcDb.DbData().Ddb)
 	if err != nil {
-		return 0, "", err
+		return dsess.RevisionTypeNone, "", err
 	}
 
 	caseSensitiveBranchName, isBranch, err := isBranch(ctx, srcDb, resolvedRevSpec)
 	if err != nil {
-		return 0, "", err
+		return dsess.RevisionTypeNone, "", err
 	}
 
 	if isBranch {
@@ -828,7 +831,7 @@ func revisionDbType(ctx *sql.Context, srcDb dsess.SqlDatabase, revSpec string) (
 
 	isTag, err := isTag(ctx, srcDb, resolvedRevSpec)
 	if err != nil {
-		return 0, "", err
+		return dsess.RevisionTypeNone, "", err
 	}
 
 	if isTag {
@@ -836,12 +839,40 @@ func revisionDbType(ctx *sql.Context, srcDb dsess.SqlDatabase, revSpec string) (
 	}
 
 	if doltdb.IsValidCommitHash(resolvedRevSpec) {
-		return dsess.RevisionTypeCommit, resolvedRevSpec, nil
+		// IsValidCommitHash just checks a regex, we need to see if the commit actually exists
+		valid, err := isValidCommitHash(ctx, srcDb, resolvedRevSpec)
+		if err != nil {
+			return 0, "", err
+		}
+		
+		if valid {
+			return dsess.RevisionTypeCommit, resolvedRevSpec, nil
+		}
 	}
 
 	return dsess.RevisionTypeNone, "", nil
 }
 
+func isValidCommitHash(ctx *sql.Context, db dsess.SqlDatabase, commitHash string) (bool, error) {
+	cs, err := doltdb.NewCommitSpec(commitHash)
+	if err != nil {
+		return false, err
+	}
+
+	for _, ddb := range db.DoltDatabases() {
+		_, err = ddb.Resolve(ctx, cs, nil)
+		if errors.Is(err, datas.ErrCommitNotFound) {
+			continue
+		} else if err != nil {
+			return false, err
+		}
+		
+		return true, nil
+	}
+	
+	return false, nil
+}
+
 func initialDbState(ctx context.Context, db dsess.SqlDatabase, branch string) (dsess.InitialDbState, error) {
 	rsr := db.DbData().Rsr
 	ddb := db.DbData().Ddb

go/libraries/doltcore/sqle/enginetest/dolt_queries.go

@@ -2590,6 +2590,38 @@ var DoltCheckoutScripts = []queries.ScriptTest{
 			},
 		},
 	},
+	{
+		Name: "Using non-existent refs",
+		SetUpScript: []string{
+			"create table t (a int primary key, b int);",
+			"insert into t values (1, 1);",
+			"call dolt_commit('-Am', 'creating table t');",
+			"call dolt_branch('b1');",
+			"call dolt_tag('tag1');",
+		},
+		Assertions: []queries.ScriptTestAssertion{
+			{
+				Query: "use mydb/b1",
+				Expected: []sql.Row{},
+			},
+			{
+				Query: "use mydb/b2",
+				ExpectedErrStr: "database not found: mydb/b2",
+			},
+			{
+				Query: "use mydb/tag1",
+				Expected: []sql.Row{},
+			},
+			{
+				Query: "use mydb/tag2",
+				ExpectedErrStr: "database not found: mydb/tag2",
+			},
+			{
+				Query: "use mydb/h4jks5lomp9u41r6902knn0pfr7lsgth",
+				ExpectedErrStr: "database not found: mydb/h4jks5lomp9u41r6902knn0pfr7lsgth",
+			},
+		},
+	},
 }
 
 var DoltInfoSchemaScripts = []queries.ScriptTest{

go/store/datas/commit.go

@@ -333,7 +333,7 @@ func LoadCommitAddr(ctx context.Context, vr types.ValueReader, addr hash.Hash) (
 		return nil, err
 	}
 	if v == nil {
-		return nil, errors.New("target commit not found")
+		return nil, ErrCommitNotFound
 	}
 	return CommitFromValue(vr.Format(), v)
 }