*: support drop session binding

bindinfo/bind_test.go

@@ -273,4 +273,10 @@ func (s *testSuite) TestSessionBinding(c *C) {
 	c.Check(row.GetString(6), NotNil)
 	c.Check(row.GetString(7), NotNil)
 
+	_, err = tk.Exec("drop session binding for select * from t where i>99")
+	c.Assert(err, IsNil)
+	bindData = handle.GetBindRecord("select * from t where i > ?", "test")
+	c.Check(bindData, NotNil)
+	c.Check(bindData.OriginalSQL, Equals, "select * from t where i > ?")
+	c.Check(bindData.Status, Equals, "deleted")
 }

bindinfo/handle.go

@@ -196,7 +196,7 @@ func (h *BindHandle) DropBindRecord(record *BindRecord) (err error) {
 			return
 		}
 
-		hash, meta := h.newBindMetaWithoutAst(record)
+		hash, meta := newBindMetaWithoutAst(record)
 		h.removeBindMeta(hash, meta)
 	}()
 
@@ -226,18 +226,9 @@ func (h *BindHandle) Size() int {
 	return size
 }
 
-// GetBindRecord return the BindMeta of the (normdOrigSQL,db) if BindMeta exist.
+// GetBindRecord return the bindMeta of the (normdOrigSQL,db) if bindMeta exist.
 func (h *BindHandle) GetBindRecord(normdOrigSQL, db string) *BindMeta {
-	hash := parser.DigestHash(normdOrigSQL)
-	bindRecords := h.bindInfo.Load().(cache)[hash]
-	if bindRecords != nil {
-		for _, bindRecord := range bindRecords {
-			if bindRecord.OriginalSQL == normdOrigSQL && bindRecord.Db == db {
-				return bindRecord
-			}
-		}
-	}
-	return nil
+	return h.bindInfo.Load().(cache).getBindRecord(normdOrigSQL, db)
 }
 
 // GetAllBindRecord return all bind record in cache.
@@ -259,7 +250,7 @@ func (h *BindHandle) newBindMeta(record *BindRecord) (hash string, meta *BindMet
 	return hash, meta, nil
 }
 
-func (h *BindHandle) newBindMetaWithoutAst(record *BindRecord) (hash string, meta *BindMeta) {
+func newBindMetaWithoutAst(record *BindRecord) (hash string, meta *BindMeta) {
 	hash = parser.DigestHash(record.OriginalSQL)
 	meta = &BindMeta{BindRecord: record}
 	return hash, meta
@@ -337,6 +328,19 @@ func (c cache) copy() cache {
 	return newCache
 }
 
+func (c cache) getBindRecord(normdOrigSQL, db string) *BindMeta {
+	hash := parser.DigestHash(normdOrigSQL)
+	bindRecords := c[hash]
+	if bindRecords != nil {
+		for _, bindRecord := range bindRecords {
+			if bindRecord.OriginalSQL == normdOrigSQL && bindRecord.Db == db {
+				return bindRecord
+			}
+		}
+	}
+	return nil
+}
+
 // isStale checks whether this BindMeta is stale compared with the other BindMeta.
 func (m *BindMeta) isStale(other *BindMeta) bool {
 	return m.OriginalSQL == other.OriginalSQL && m.Db == other.Db &&

bindinfo/session_handle.go

@@ -70,6 +70,15 @@ func (h *SessionHandle) AddBindRecord(record *BindRecord) error {
 	return err
 }
 
+// DropBindRecord drops a BindRecord in the cache.
+func (h *SessionHandle) DropBindRecord(record *BindRecord) {
+	meta := &BindMeta{BindRecord: record}
+	meta.Status = deleted
+	hash := parser.DigestHash(record.OriginalSQL)
+	h.ch.removeDeletedBindMeta(hash, meta)
+	h.appendBindMeta(hash, meta)
+}
+
 // GetBindRecord return the BindMeta of the (normdOrigSQL,db) if BindMeta exist.
 func (h *SessionHandle) GetBindRecord(normdOrigSQL, db string) *BindMeta {
 	hash := parser.DigestHash(normdOrigSQL)

executor/bind.go

@@ -57,14 +57,15 @@ func (e *SQLBindExec) Next(ctx context.Context, req *chunk.RecordBatch) error {
 }
 
 func (e *SQLBindExec) dropSQLBind() error {
-	if !e.isGlobal {
-		return errors.New("drop non-global sql bind is not supported")
-	}
-
 	record := &bindinfo.BindRecord{
 		OriginalSQL: e.normdOrigSQL,
 		Db:          e.ctx.GetSessionVars().CurrentDB,
 	}
+	if !e.isGlobal {
+		handle := e.ctx.Value(bindinfo.SessionBindInfoKeyType).(*bindinfo.SessionHandle)
+		handle.DropBindRecord(record)
+		return nil
+	}
 	return domain.GetDomain(e.ctx).BindHandle().DropBindRecord(record)
 }