comments

Author: James Cor

sql/expression/function/aggregation/window_framer.go

@@ -319,23 +319,28 @@ func (f *rowFramerBase) Interval() (sql.WindowInterval, error) {
 // frame:  {0,3},   {1,3}, {2,3}, {3,5},   {3,5},   {4,5}
 // rows:   [0,1,2], [1,2], [2],   [4,4,5], [4,4,5], [5]
 type rangeFramerBase struct {
-	startNFollowing sql.Expression
-	endNFollowing   sql.Expression
-	startNPreceding sql.Expression
-	endNPreceding   sql.Expression
+	startNFollowing sql.Expression // optional
+	endNFollowing   sql.Expression // optional
+	startNPreceding sql.Expression // optional
+	endNPreceding   sql.Expression // optional
+	// boundary arithmetic on [orderBy] for range start value
+	// is set unless [unboundedPreceding] is true
 	startInclusion  sql.Expression
+	// boundary arithmetic on [orderBy] for range end value
+	// is set unless [unboundedFollowing] is true
 	endInclusion    sql.Expression
+	// reference expression for boundary calculation
 	orderBy         sql.Expression
 
 	idx                int
-	partitionEnd       int
-	frameStart         int
-	frameEnd           int
 	partitionStart     int
-	startCurrentRow    bool
-	endCurrentRow      bool
-	unboundedFollowing bool
-	unboundedPreceding bool
+	partitionEnd       int
+	frameStart         int  // optional
+	frameEnd           int  // optional
+	startCurrentRow    bool // optional
+	endCurrentRow      bool // optional
+	unboundedFollowing bool // optional
+	unboundedPreceding bool // optional
 	partitionSet       bool
 }
 

sql/index.go

@@ -154,6 +154,10 @@ type IndexLookup struct {
 	Index               Index
 	Ranges              RangeCollection
 	VectorOrderAndLimit OrderAndLimit
+	// IsPointLookup is true if the lookup will return one or zero
+	// values; the range is null safe, the index is unique, every index
+	// column has a range expression, and every range expression is an
+	// exact equality.
 	IsPointLookup       bool
 	IsEmptyRange        bool
 	IsSpatialLookup     bool

sql/iters/rel_iters.go

@@ -160,12 +160,12 @@ type JsonTableColOpts struct {
 type JsonTableCol struct {
 	err      error
 	Opts     *JsonTableColOpts
-	Path     string
-	Cols     []*JsonTableCol
+	Path     string // if there are nested columns, this is a schema Path, otherwise it is a col Path
+	Cols     []*JsonTableCol // nested columns
 	data     []interface{}
 	pos      int
 	currSib  int
-	finished bool
+	finished bool // exhausted all rows in data
 }
 
 // IsSibling returns if the jsonTableCol contains multiple columns

sql/plan/dbddl.go

@@ -113,6 +113,8 @@ func (c *CreateSchema) WithChildren(children ...sql.Node) (sql.Node, error) {
 // DropDB removes a databases from the Catalog and updates the active database if it gets removed itself.
 type DropDB struct {
 	Catalog   sql.Catalog
+	// EventScheduler is used to notify EventSchedulerStatus of database deletion,
+	// so the events of this database in the scheduler will be removed.
 	Scheduler sql.EventScheduler
 	DbName    string
 	IfExists  bool

sql/plan/subqueryalias.go

@@ -33,6 +33,7 @@ type SubqueryAlias struct {
 
 	id sql.TableId
 
+	// OuterScopeVisibility is true when a SubqueryAlias (i.e. derived table) is contained in a subquery
 	// expression and is eligible to have visibility to outer scopes of the query.
 	OuterScopeVisibility bool
 	Volatile             bool

sql/plan/update.go

@@ -32,6 +32,7 @@ var ErrUpdateUnexpectedSetResult = errors.NewKind("attempted to set field but ex
 type Update struct {
 	UnaryNode
 	checks sql.CheckConstraints
+	// Returning is a list of expressions to return after the update operation. This feature is not
 	// supported in MySQL's syntax, but is exposed through PostgreSQL's syntax.
 	Returning []sql.Expression
 	// IsJoin is true only for explicit UPDATE JOIN queries. It's possible for Update.IsJoin to be false and