use precedence fix

Author: elianddb

sql/analyzer/costed_index_scan.go

@@ -114,8 +114,8 @@ func indexSearchableLookup(ctx *sql.Context, n sql.Node, rt sql.TableNode, looku
 		ret = plan.NewFilter(newFilter, ret)
 	}
 
-	if fds != nil && fds.HasMax1Row() && !qFlags.JoinIsSet() && !qFlags.SubqueryIsSet() && lookup.Ranges.Len() == 1 {
-		// Strict index lookup without a join or subquery scope will return
+	if fds != nil && fds.HasMax1Row() && !qFlags.JoinIsSet() && !qFlags.SubqueryIsSet() && !qFlags.IsSet(sql.QFlagUnion) && lookup.Ranges.Len() == 1 {
+		// Index lookup without join/subquery/union scope returns
 		// at most one row. We could also use some sort of scope counting
 		// to check for single scope.
 		qFlags.Set(sql.QFlagMax1Row)

sql/analyzer/resolve_unions.go

@@ -41,6 +41,9 @@ func resolveUnions(ctx *sql.Context, a *Analyzer, n sql.Node, scope *plan.Scope,
 		subqueryCtx, cancelFunc := ctx.NewSubContext()
 		defer cancelFunc()
 
+		// Prevent max1Row optimization in union branches
+		qFlags.Set(sql.QFlagUnion)
+
 		left, _, err := a.analyzeThroughBatch(subqueryCtx, u.Left(), scope, "default-rules", sel, qFlags)
 		if err != nil {
 			return nil, transform.SameTree, err
@@ -79,6 +82,9 @@ func finalizeUnions(ctx *sql.Context, a *Analyzer, n sql.Node, scope *plan.Scope
 		subqueryCtx, cancelFunc := ctx.NewSubContext()
 		defer cancelFunc()
 
+		// Prevent max1Row optimization in union branches
+		qFlags.Set(sql.QFlagUnion)
+
 		scope.SetJoin(false)
 		// TODO we could detect tree modifications here, skip rebuilding
 		left, _, err := a.analyzeStartingAtBatch(subqueryCtx, u.Left(), scope, "default-rules", NewFinalizeUnionSel(sel), qFlags)

sql/analyzer/validate_create_table.go

@@ -792,8 +792,8 @@ func validateAutoIncrementModify(schema sql.Schema, keyedColumns map[string]bool
 	seen := false
 	for _, col := range schema {
 		if col.AutoIncrement {
-			// Under MySQL 8.4+, AUTO_INCREMENT columns must be integer types, but not BIT types.
-			if !types.IsInteger(col.Type) || types.IsBit(col.Type) {
+			// AUTO_INCREMENT requires integer types
+			if !types.IsInteger(col.Type) {
 				return sql.ErrInvalidColumnSpecifier.New(col.Name)
 			}
 			// keyedColumns == nil means they are trying to add auto_increment column

sql/plan/set_op.go

@@ -19,6 +19,7 @@ import (
 	"strings"
 
 	"github.com/dolthub/go-mysql-server/sql"
+	"github.com/dolthub/go-mysql-server/sql/types"
 )
 
 const (
@@ -97,9 +98,12 @@ func (s *SetOp) Schema() sql.Schema {
 	ls := s.left.Schema()
 	rs := s.right.Schema()
 	ret := make([]*sql.Column, len(ls))
+	
 	for i := range ls {
 		c := *ls[i]
 		if i < len(rs) {
+			// Use MySQL type precedence for UNION columns
+			c.Type = types.GeneralizeTypes(ls[i].Type, rs[i].Type)
 			c.Nullable = ls[i].Nullable || rs[i].Nullable
 		}
 		ret[i] = &c

sql/query_flags.go

@@ -41,6 +41,7 @@ const (
 	QFlagLimit
 	QFlagInterval
 	QFlagAnyAgg
+	QFlagUnion
 
 	// QFlagMax1Row indicates that a query can only return at most one row
 	QFlagMax1Row

sql/types/typecheck.go

@@ -230,7 +230,7 @@ func IsUnsigned(t sql.Type) bool {
 	if svt, ok := t.(sql.SystemVariableType); ok {
 		t = svt.UnderlyingType()
 	}
-	return t == Uint8 || t == Uint16 || t == Uint24 || t == Uint32 || t == Uint64 || IsBit(t)
+	return t == Uint8 || t == Uint16 || t == Uint24 || t == Uint32 || t == Uint64
 }
 
 // IsYear checks if t is a year type.