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Merge pull request #750 from erizocosmico/feature/refactor-natural-jo…
…in-rule sql/analyzer: refactor resolve_natural_joins rule
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,266 +1,137 @@ | ||
| package analyzer | ||
|
|
||
| import ( | ||
| "reflect" | ||
| "strings" | ||
|
|
||
| "github.com/src-d/go-mysql-server/sql" | ||
| "github.com/src-d/go-mysql-server/sql/expression" | ||
| "github.com/src-d/go-mysql-server/sql/plan" | ||
| ) | ||
|
|
||
| type transformedJoin struct { | ||
| node sql.Node | ||
| condCols map[string]*transformedSource | ||
| } | ||
|
|
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| type transformedSource struct { | ||
| correct string | ||
| wrong []string | ||
| } | ||
|
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| func resolveNaturalJoins(ctx *sql.Context, a *Analyzer, n sql.Node) (sql.Node, error) { | ||
| span, _ := ctx.Span("resolve_natural_joins") | ||
| defer span.Finish() | ||
|
|
||
| if n.Resolved() { | ||
| return n, nil | ||
| } | ||
|
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| var transformed []*transformedJoin | ||
| var aliasTables = map[string][]string{} | ||
| var colsToUnresolve = map[string]*transformedSource{} | ||
| a.Log("resolving natural joins, node of type %T", n) | ||
| node, err := n.TransformUp(func(n sql.Node) (sql.Node, error) { | ||
| a.Log("transforming node of type: %T", n) | ||
| var replacements = make(map[tableCol]tableCol) | ||
| var tableAliases = make(map[string]string) | ||
|
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| if alias, ok := n.(*plan.TableAlias); ok { | ||
| table := alias.Child.(*plan.ResolvedTable).Name() | ||
| aliasTables[alias.Name()] = append(aliasTables[alias.Name()], table) | ||
| return n.TransformUp(func(n sql.Node) (sql.Node, error) { | ||
| switch n := n.(type) { | ||
| case *plan.TableAlias: | ||
| alias := n.Name() | ||
| table := n.Child.(*plan.ResolvedTable).Name() | ||
| tableAliases[strings.ToLower(alias)] = table | ||
| return n, nil | ||
| } | ||
|
|
||
| if n.Resolved() { | ||
| case *plan.NaturalJoin: | ||
| return resolveNaturalJoin(n, replacements) | ||
| case sql.Expressioner: | ||
| return replaceExpressions(n, replacements, tableAliases) | ||
| default: | ||
| return n, nil | ||
| } | ||
| }) | ||
| } | ||
|
|
||
| join, ok := n.(*plan.NaturalJoin) | ||
| if !ok { | ||
| return n, nil | ||
| } | ||
|
|
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| // we need both leaves resolved before resolving this one | ||
| if !join.Left.Resolved() || !join.Right.Resolved() { | ||
| return n, nil | ||
| } | ||
|
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| leftSchema, rightSchema := join.Left.Schema(), join.Right.Schema() | ||
|
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| var conditions, common, left, right []sql.Expression | ||
| var seen = make(map[string]struct{}) | ||
|
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| for i, lcol := range leftSchema { | ||
| var found bool | ||
| leftCol := expression.NewGetFieldWithTable( | ||
| i, | ||
| lcol.Type, | ||
| lcol.Source, | ||
| lcol.Name, | ||
| lcol.Nullable, | ||
| ) | ||
|
|
||
| for j, rcol := range rightSchema { | ||
| if lcol.Name == rcol.Name { | ||
| common = append(common, leftCol) | ||
|
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| conditions = append( | ||
| conditions, | ||
| expression.NewEquals( | ||
| leftCol, | ||
| expression.NewGetFieldWithTable( | ||
| len(leftSchema)+j, | ||
| rcol.Type, | ||
| rcol.Source, | ||
| rcol.Name, | ||
| rcol.Nullable, | ||
| ), | ||
| ), | ||
| ) | ||
|
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| found = true | ||
| seen[lcol.Name] = struct{}{} | ||
| if source, ok := colsToUnresolve[lcol.Name]; ok { | ||
| source.correct = lcol.Source | ||
| source.wrong = append(source.wrong, rcol.Source) | ||
| } else { | ||
| colsToUnresolve[lcol.Name] = &transformedSource{ | ||
| correct: lcol.Source, | ||
| wrong: []string{rcol.Source}, | ||
| } | ||
| } | ||
|
|
||
| break | ||
| } | ||
| } | ||
| func resolveNaturalJoin( | ||
| n *plan.NaturalJoin, | ||
| replacements map[tableCol]tableCol, | ||
| ) (sql.Node, error) { | ||
| // Both sides of the natural join need to be resolved in order to resolve | ||
| // the natural join itself. | ||
| if !n.Left.Resolved() || !n.Right.Resolved() { | ||
| return n, nil | ||
| } | ||
|
|
||
| if !found { | ||
| left = append(left, leftCol) | ||
| leftSchema := n.Left.Schema() | ||
| rightSchema := n.Right.Schema() | ||
|
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| var conditions, common, left, right []sql.Expression | ||
| for i, lcol := range leftSchema { | ||
| leftCol := expression.NewGetFieldWithTable( | ||
| i, | ||
| lcol.Type, | ||
| lcol.Source, | ||
| lcol.Name, | ||
| lcol.Nullable, | ||
| ) | ||
| if idx, rcol := findCol(rightSchema, lcol.Name); rcol != nil { | ||
| common = append(common, leftCol) | ||
| replacements[tableCol{strings.ToLower(rcol.Source), strings.ToLower(rcol.Name)}] = tableCol{ | ||
| strings.ToLower(lcol.Source), strings.ToLower(lcol.Name), | ||
| } | ||
| } | ||
|
|
||
| if len(conditions) == 0 { | ||
| return plan.NewCrossJoin(join.Left, join.Right), nil | ||
| } | ||
|
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| for i, col := range rightSchema { | ||
| if _, ok := seen[col.Name]; !ok { | ||
| right = append( | ||
| right, | ||
| conditions = append( | ||
| conditions, | ||
| expression.NewEquals( | ||
| leftCol, | ||
| expression.NewGetFieldWithTable( | ||
| len(leftSchema)+i, | ||
| col.Type, | ||
| col.Source, | ||
| col.Name, | ||
| col.Nullable, | ||
| len(leftSchema)+idx, | ||
| rcol.Type, | ||
| rcol.Source, | ||
| rcol.Name, | ||
| rcol.Nullable, | ||
| ), | ||
| ) | ||
| } | ||
| } | ||
|
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| projections := append(append(common, left...), right...) | ||
|
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| tj := &transformedJoin{ | ||
| node: plan.NewProject( | ||
| projections, | ||
| plan.NewInnerJoin( | ||
| join.Left, | ||
| join.Right, | ||
| expression.JoinAnd(conditions...), | ||
| ), | ||
| ), | ||
| condCols: colsToUnresolve, | ||
| ) | ||
| } else { | ||
| left = append(left, leftCol) | ||
| } | ||
|
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| transformed = append(transformed, tj) | ||
|
|
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| return tj.node, nil | ||
| }) | ||
|
|
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| if err != nil || len(transformed) == 0 { | ||
| return node, err | ||
| } | ||
|
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| var transformedSeen bool | ||
| return node.TransformUp(func(node sql.Node) (sql.Node, error) { | ||
| if ok, _ := isTransformedNode(node, transformed); ok { | ||
| transformedSeen = true | ||
| return node, nil | ||
| } | ||
|
|
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| if !transformedSeen { | ||
| return node, nil | ||
| } | ||
|
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| expressioner, ok := node.(sql.Expressioner) | ||
| if !ok { | ||
| return node, nil | ||
| } | ||
|
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| return expressioner.TransformExpressions(func(e sql.Expression) (sql.Expression, error) { | ||
| var col, table string | ||
| switch e := e.(type) { | ||
| case *expression.GetField: | ||
| col, table = e.Name(), e.Table() | ||
| case *expression.UnresolvedColumn: | ||
| col, table = e.Name(), e.Table() | ||
| default: | ||
| return e, nil | ||
| } | ||
|
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| sources, ok := colsToUnresolve[col] | ||
| if !ok { | ||
| return e, nil | ||
| } | ||
|
|
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| if !mustUnresolve(aliasTables, table, sources.wrong) { | ||
| return e, nil | ||
| } | ||
|
|
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| return expression.NewUnresolvedQualifiedColumn( | ||
| sources.correct, | ||
| col, | ||
| ), nil | ||
| }) | ||
| }) | ||
| } | ||
|
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| func isTransformedNode(node sql.Node, transformed []*transformedJoin) (is bool, colsToUnresolve map[string]*transformedSource) { | ||
| var project *plan.Project | ||
| var join *plan.InnerJoin | ||
| switch n := node.(type) { | ||
| case *plan.Project: | ||
| var ok bool | ||
| join, ok = n.Child.(*plan.InnerJoin) | ||
| if !ok { | ||
| return | ||
| } | ||
|
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| project = n | ||
| case *plan.InnerJoin: | ||
| join = n | ||
|
|
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| default: | ||
| return | ||
| if len(conditions) == 0 { | ||
| return plan.NewCrossJoin(n.Left, n.Right), nil | ||
| } | ||
|
|
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| for _, t := range transformed { | ||
| tproject, ok := t.node.(*plan.Project) | ||
| if !ok { | ||
| return | ||
| } | ||
|
|
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| tjoin, ok := tproject.Child.(*plan.InnerJoin) | ||
| if !ok { | ||
| return | ||
| } | ||
|
|
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| if project != nil && !reflect.DeepEqual(project.Projections, tproject.Projections) { | ||
| continue | ||
| } | ||
|
|
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| if reflect.DeepEqual(join.Cond, tjoin.Cond) { | ||
| is = true | ||
| colsToUnresolve = t.condCols | ||
| for i, col := range rightSchema { | ||
| source := strings.ToLower(col.Source) | ||
| name := strings.ToLower(col.Name) | ||
| if _, ok := replacements[tableCol{source, name}]; !ok { | ||
| right = append( | ||
| right, | ||
| expression.NewGetFieldWithTable( | ||
| len(leftSchema)+i, | ||
| col.Type, | ||
| col.Source, | ||
| col.Name, | ||
| col.Nullable, | ||
| ), | ||
| ) | ||
| } | ||
| } | ||
|
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| return | ||
| return plan.NewProject( | ||
| append(append(common, left...), right...), | ||
| plan.NewInnerJoin(n.Left, n.Right, expression.JoinAnd(conditions...)), | ||
| ), nil | ||
| } | ||
|
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| func mustUnresolve(aliasTable map[string][]string, table string, wrongSources []string) bool { | ||
| return isIn(table, wrongSources) || isAliasFor(aliasTable, table, wrongSources) | ||
| } | ||
|
|
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| func isIn(s string, l []string) bool { | ||
| for _, e := range l { | ||
| if s == e { | ||
| return true | ||
| func findCol(s sql.Schema, name string) (int, *sql.Column) { | ||
| for i, c := range s { | ||
| if strings.ToLower(c.Name) == strings.ToLower(name) { | ||
| return i, c | ||
| } | ||
| } | ||
|
|
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| return false | ||
| return -1, nil | ||
| } | ||
|
|
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| func isAliasFor(aliasTable map[string][]string, table string, wrongSources []string) bool { | ||
| tables, ok := aliasTable[table] | ||
| if !ok { | ||
| return false | ||
| } | ||
| func replaceExpressions( | ||
| n sql.Expressioner, | ||
| replacements map[tableCol]tableCol, | ||
| tableAliases map[string]string, | ||
| ) (sql.Node, error) { | ||
| return n.TransformExpressions(func(e sql.Expression) (sql.Expression, error) { | ||
| switch e := e.(type) { | ||
| case *expression.GetField, *expression.UnresolvedColumn: | ||
| var tableName = e.(sql.Tableable).Table() | ||
| if t, ok := tableAliases[strings.ToLower(tableName)]; ok { | ||
| tableName = t | ||
| } | ||
|
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| for _, t := range tables { | ||
| if isIn(t, wrongSources) { | ||
| return true | ||
| name := e.(sql.Nameable).Name() | ||
| if col, ok := replacements[tableCol{strings.ToLower(tableName), strings.ToLower(name)}]; ok { | ||
| return expression.NewUnresolvedQualifiedColumn(col.table, col.col), nil | ||
| } | ||
| } | ||
| } | ||
|
|
||
| return false | ||
| return e, nil | ||
| }) | ||
| } |
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