Fix up hash interface and speed up save queries 10x

Fix all optimizer

graph/sql/optimizers.go

@@ -164,7 +164,8 @@ func (qs *QuadStore) optimizeLinksTo(it *iterator.LinksTo) (graph.Iterator, bool
 		return newit, true
 	case graph.All:
 		linkit := &SQLLinkIterator{
-			size: qs.Size(),
+			tableName: newTableName(),
+			size:      qs.Size(),
 		}
 		for _, t := range primary.Tagger().Tags() {
 			linkit.tagdirs = append(linkit.tagdirs, tagDir{

graph/sql/sql_iterator.go

@@ -290,7 +290,7 @@ func (it *SQLIterator) makeCursor(next bool, value graph.Value) error {
 	}
 	var q string
 	var values []string
-	q, values = it.sql.buildSQL(next, value, false)
+	q, values = it.sql.buildSQL(next, value, true)
 	q = convertToPostgres(q, values)
 	ivalues := make([]interface{}, 0, len(values))
 	for _, v := range values {

graph/sql/sql_link_iterator.go

@@ -71,7 +71,7 @@ type sqlItDir struct {
 type sqlIterator interface {
 	sqlClone() sqlIterator
 
-	buildSQL(next bool, val graph.Value, hash bool) (string, []string)
+	buildSQL(next bool, val graph.Value, topLevel bool) (string, []string)
 	getTables() []tableDef
 	getTags() []tagDir
 	buildWhere() (string, []string)
@@ -246,10 +246,13 @@ func (l *SQLLinkIterator) tableID() tagDir {
 	}
 }
 
-func (l *SQLLinkIterator) buildSQL(next bool, val graph.Value, hash bool) (string, []string) {
+func (l *SQLLinkIterator) buildSQL(next bool, val graph.Value, topLevel bool) (string, []string) {
-	query := "SELECT DISTINCT "
+	query := "SELECT "
+	if topLevel {
+		query += "DISTINCT "
+	}
 	hashs := ""
-	if hash {
+	if !topLevel {
 		hashs = "_hash"
 	}
 	t := []string{
@@ -270,14 +273,18 @@ func (l *SQLLinkIterator) buildSQL(next bool, val graph.Value, hash bool) (strin
 		t = append(t, fmt.Sprintf("%s as %s", k.table, k.name))
 	}
 	query += strings.Join(t, ", ")
-	query += " WHERE "
 	constraint, wherevalues := l.buildWhere()
+	if constraint != "" {
+		query += " WHERE "
+	}
 
 	values = append(values, wherevalues...)
 	if !next {
 		v := val.(quad.Quad)
 		if constraint != "" {
 			constraint += " AND "
+		} else {
+			constraint += " WHERE "
 		}
 		t = []string{
 			fmt.Sprintf("%s.subject_hash = ?", l.tableName),

graph/sql/sql_node_intersection.go

@@ -103,7 +103,7 @@ func (n *SQLNodeIntersection) buildSubqueries() []tableDef {
 	for i, it := range n.nodeIts {
 		var td tableDef
 		var table string
-		table, td.values = it.buildSQL(true, nil, true)
+		table, td.values = it.buildSQL(true, nil, false)
 		td.table = fmt.Sprintf("\n(%s)", table[:len(table)-1])
 		td.name = n.nodetables[i]
 		out = append(out, td)
@@ -159,11 +159,14 @@ func (n *SQLNodeIntersection) buildWhere() (string, []string) {
 	return query, vals
 }
 
-func (n *SQLNodeIntersection) buildSQL(next bool, val graph.Value, _ bool) (string, []string) {
+func (n *SQLNodeIntersection) buildSQL(next bool, val graph.Value, topLevel bool) (string, []string) {
 	topData := n.tableID()
 	tags := []tagDir{topData}
 	tags = append(tags, n.getTags()...)
-	query := "SELECT DISTINCT "
+	query := "SELECT "
+	if topLevel {
+		query += "DISTINCT "
+	}
 	var t []string
 	for _, v := range tags {
 		t = append(t, v.String())

graph/sql/sql_node_iterator.go

@@ -160,11 +160,14 @@ func (n *SQLNodeIterator) buildWhere() (string, []string) {
 	return query, vals
 }
 
-func (n *SQLNodeIterator) buildSQL(next bool, val graph.Value, _ bool) (string, []string) {
+func (n *SQLNodeIterator) buildSQL(next bool, val graph.Value, topLevel bool) (string, []string) {
 	topData := n.tableID()
 	tags := []tagDir{topData}
 	tags = append(tags, n.getTags()...)
-	query := "SELECT DISTINCT "
+	query := "SELECT "
+	if topLevel {
+		query += "DISTINCT "
+	}
 	var t []string
 	for _, v := range tags {
 		t = append(t, v.String())