planner: simplify the session binding handler code

pkg/bindinfo/binding.go

@@ -141,6 +141,7 @@ func prepareHints(sctx sessionctx.Context, binding *Binding) error {
 	if err != nil {
 		return err
 	}
+	tableNames := CollectTableNames(bindingStmt)
 	isFuzzy := isFuzzyBinding(bindingStmt)
 	if isFuzzy {
 		dbName = "*" // ues '*' for universal bindings
@@ -172,6 +173,7 @@ func prepareHints(sctx sessionctx.Context, binding *Binding) error {
 	}
 	binding.Hint = hintsSet
 	binding.ID = hintsStr
+	binding.TableNames = tableNames
 	return nil
 }
 

pkg/bindinfo/global_handle.go

@@ -493,32 +493,21 @@ func newBinding(sctx sessionctx.Context, row chunk.Row) (string, Binding, error)
 	if status == Using {
 		status = Enabled
 	}
-	defaultDB := row.GetString(2)
-
-	bindSQL := row.GetString(1)
-	charset, collation := row.GetString(6), row.GetString(7)
-	stmt, err := parser.New().ParseOneStmt(bindSQL, charset, collation)
-	if err != nil {
-		return "", Binding{}, err
-	}
-	tableNames := CollectTableNames(stmt)
-
 	binding := Binding{
 		OriginalSQL: row.GetString(0),
-		Db:          strings.ToLower(defaultDB),
-		BindSQL:     bindSQL,
+		Db:          strings.ToLower(row.GetString(2)),
+		BindSQL:     row.GetString(1),
 		Status:      status,
 		CreateTime:  row.GetTime(4),
 		UpdateTime:  row.GetTime(5),
-		Charset:     charset,
-		Collation:   collation,
+		Charset:     row.GetString(6),
+		Collation:   row.GetString(7),
 		Source:      row.GetString(8),
 		SQLDigest:   row.GetString(9),
 		PlanDigest:  row.GetString(10),
-		TableNames:  tableNames,
 	}
 	sqlDigest := parser.DigestNormalized(binding.OriginalSQL)
-	err = prepareHints(sctx, &binding)
+	err := prepareHints(sctx, &binding)
 	sctx.GetSessionVars().CurrentDB = binding.Db
 	return sqlDigest.String(), binding, err
 }

pkg/bindinfo/session_handle.go

@@ -21,7 +21,6 @@ import (
 	"time"
 
 	"github.com/pingcap/errors"
-	"github.com/pingcap/tidb/pkg/bindinfo/norm"
 	"github.com/pingcap/tidb/pkg/metrics"
 	"github.com/pingcap/tidb/pkg/parser"
 	"github.com/pingcap/tidb/pkg/parser/ast"
@@ -56,13 +55,13 @@ type SessionBindingHandle interface {
 
 // sessionBindingHandle is used to handle all session sql bind operations.
 type sessionBindingHandle struct {
-	ch BindingCache
+	ch FuzzyBindingCache
 }
 
 // NewSessionBindingHandle creates a new SessionBindingHandle.
 func NewSessionBindingHandle() SessionBindingHandle {
 	sessionHandle := &sessionBindingHandle{}
-	sessionHandle.ch = newBindCache()
+	sessionHandle.ch = newFuzzyBindingCache()
 	return sessionHandle
 }
 
@@ -104,33 +103,7 @@ func (h *sessionBindingHandle) DropSessionBinding(sqlDigest string) error {
 
 // MatchSessionBinding returns the matched binding for this statement.
 func (h *sessionBindingHandle) MatchSessionBinding(sctx sessionctx.Context, fuzzyDigest string, tableNames []*ast.TableName) (matchedBinding Binding, isMatched bool) {
-	// The current implementation is simplistic, but session binding is only for test purpose, so
-	// there shouldn't be many session bindings, and to keep it simple, this implementation is acceptable.
-	leastWildcards := len(tableNames) + 1
-	bindings := h.ch.GetAllBindings()
-	enableFuzzyBinding := sctx.GetSessionVars().EnableFuzzyBinding
-	for _, binding := range bindings {
-		bindingStmt, err := parser.New().ParseOneStmt(binding.BindSQL, binding.Charset, binding.Collation)
-		if err != nil {
-			return
-		}
-		_, bindingFuzzyDigest := norm.NormalizeStmtForBinding(bindingStmt, norm.WithFuzz(true))
-		if bindingFuzzyDigest != fuzzyDigest {
-			continue
-		}
-		bindingTableNames := CollectTableNames(bindingStmt)
-
-		numWildcards, matched := fuzzyMatchBindingTableName(sctx.GetSessionVars().CurrentDB, tableNames, bindingTableNames)
-		if matched && numWildcards > 0 && sctx != nil && !enableFuzzyBinding {
-			continue // fuzzy binding is disabled, skip this binding
-		}
-		if matched && numWildcards < leastWildcards {
-			matchedBinding = binding
-			isMatched = true
-			leastWildcards = numWildcards
-		}
-	}
-	return
+	return h.ch.FuzzyMatchingBinding(sctx, fuzzyDigest, tableNames)
 }
 
 // GetAllSessionBindings return all session bind info.