Merge pull request cockroachdb#12240 from knz/fix-using-join

Miscellaneous JOIN improvements.

pkg/sql/data_source.go

@@ -151,6 +151,47 @@ type sourceAlias struct {
 	columnRange columnRange
 }
 
+func (src *dataSourceInfo) String() string {
+	var buf bytes.Buffer
+	for i := range src.sourceColumns {
+		if i > 0 {
+			buf.WriteByte('\t')
+		}
+		fmt.Fprintf(&buf, "%d", i)
+	}
+	buf.WriteString("\toutput column positions\n")
+	for i, c := range src.sourceColumns {
+		if i > 0 {
+			buf.WriteByte('\t')
+		}
+		if c.hidden {
+			buf.WriteByte('*')
+		}
+		buf.WriteString(c.Name)
+	}
+	buf.WriteString("\toutput column names\n")
+	for _, a := range src.sourceAliases {
+		for i := range src.sourceColumns {
+			if i > 0 {
+				buf.WriteByte('\t')
+			}
+			for _, j := range a.columnRange {
+				if i == j {
+					buf.WriteString("x")
+					break
+				}
+			}
+		}
+		if a.name == anonymousTable {
+			buf.WriteString("\t<anonymous table>")
+		} else {
+			fmt.Fprintf(&buf, "\t'%s'", a.name.String())
+		}
+		fmt.Fprintf(&buf, " - %q\n", a.columnRange)
+	}
+	return buf.String()
+}
+
 type sourceAliases []sourceAlias
 
 // srcIdx looks up a source by qualified name and returns the index of the
@@ -622,40 +663,44 @@ func (sources multiSourceInfo) findColumn(c *parser.ColumnItem) (srcIdx int, col
 		c.TableName.DatabaseName = tableName.DatabaseName
 	}
 
+	findColHelper := func(src *dataSourceInfo, iSrc, srcIdx, colIdx int, idx int) (int, int, error) {
+		col := src.sourceColumns[idx]
+		if parser.ReNormalizeName(col.Name) == colName {
+			if colIdx != invalidColIdx {
+				return invalidSrcIdx, invalidColIdx, fmt.Errorf("column reference %q is ambiguous", c)
+			}
+			srcIdx = iSrc
+			colIdx = idx
+		}
+		return srcIdx, colIdx, nil
+	}
+
 	colIdx = invalidColIdx
 	for iSrc, src := range sources {
-		findColHelper := func(src *dataSourceInfo, iSrc, srcIdx, colIdx int, idx int) (int, int, error) {
-			col := src.sourceColumns[idx]
-			if parser.ReNormalizeName(col.Name) == colName {
-				if colIdx != invalidColIdx {
-					return invalidSrcIdx, invalidColIdx, fmt.Errorf("column reference %q is ambiguous", c)
-				}
-				srcIdx = iSrc
-				colIdx = idx
+		colRange, ok := src.sourceAliases.columnRange(tableName)
+		if !ok {
+			// The data source "src" has no column for table tableName.
+			// Try again with the net one.
+			continue
+		}
+		for _, idx := range colRange {
+			srcIdx, colIdx, err = findColHelper(src, iSrc, srcIdx, colIdx, idx)
+			if err != nil {
+				return srcIdx, colIdx, err
 			}
-			return srcIdx, colIdx, nil
 		}
+	}
 
-		if tableName.Table() == "" {
+	if colIdx == invalidColIdx && tableName.Table() == "" {
+		// Try harder: unqualified column names can look at all
+		// columns, not just columns of the anonymous table.
+		for iSrc, src := range sources {
 			for idx := 0; idx < len(src.sourceColumns); idx++ {
 				srcIdx, colIdx, err = findColHelper(src, iSrc, srcIdx, colIdx, idx)
 				if err != nil {
 					return srcIdx, colIdx, err
 				}
 			}
-		} else {
-			colRange, ok := src.sourceAliases.columnRange(tableName)
-			if !ok {
-				// The data source "src" has no column for table tableName.
-				// Try again with the net one.
-				continue
-			}
-			for _, idx := range colRange {
-				srcIdx, colIdx, err = findColHelper(src, iSrc, srcIdx, colIdx, idx)
-				if err != nil {
-					return srcIdx, colIdx, err
-				}
-			}
 		}
 	}
 
@@ -666,55 +711,33 @@ func (sources multiSourceInfo) findColumn(c *parser.ColumnItem) (srcIdx int, col
 	return srcIdx, colIdx, nil
 }
 
-// concatDataSourceInfos creates a new dataSourceInfo that represents
-// the side-by-side concatenation of the two data sources described by
-// its arguments.
-func concatDataSourceInfos(left *dataSourceInfo, right *dataSourceInfo) *dataSourceInfo {
-	aliases := make(sourceAliases, 0, len(left.sourceAliases)+len(right.sourceAliases))
-	aliases = append(aliases, left.sourceAliases...)
-
-	nColsLeft := len(left.sourceColumns)
-	for _, alias := range right.sourceAliases {
-		newRange := make(columnRange, len(alias.columnRange))
-		for i, idx := range alias.columnRange {
-			newRange[i] = idx + nColsLeft
-		}
-		aliases = append(aliases, sourceAlias{
-			name:        alias.name,
-			columnRange: newRange,
-		})
-	}
-
-	columns := make(ResultColumns, 0, len(left.sourceColumns)+len(right.sourceColumns))
-	columns = append(columns, left.sourceColumns...)
-	columns = append(columns, right.sourceColumns...)
-
-	return &dataSourceInfo{sourceColumns: columns, sourceAliases: aliases}
-}
-
 // findTableAlias returns the first table alias providing the column
 // index given as argument. The index must be valid.
-func (src *dataSourceInfo) findTableAlias(colIdx int) parser.TableName {
+func (src *dataSourceInfo) findTableAlias(colIdx int) (parser.TableName, bool) {
 	for _, alias := range src.sourceAliases {
 		for _, idx := range alias.columnRange {
 			if colIdx == idx {
-				return alias.name
+				return alias.name, true
 			}
 		}
 	}
-	panic(fmt.Sprintf("no alias for position %d in %v", colIdx, src.sourceAliases))
+	return anonymousTable, false
 }
 
 func (src *dataSourceInfo) FormatVar(buf *bytes.Buffer, f parser.FmtFlags, colIdx int) {
 	if f == parser.FmtQualify {
-		tableAlias := src.findTableAlias(colIdx)
-		if tableAlias.TableName != "" {
-			if tableAlias.DatabaseName != "" {
-				parser.FormatNode(buf, f, tableAlias.DatabaseName)
+		tableAlias, found := src.findTableAlias(colIdx)
+		if found {
+			if tableAlias.TableName != "" {
+				if tableAlias.DatabaseName != "" {
+					parser.FormatNode(buf, f, tableAlias.DatabaseName)
+					buf.WriteByte('.')
+				}
+				parser.FormatNode(buf, f, tableAlias.TableName)
 				buf.WriteByte('.')
 			}
-			parser.FormatNode(buf, f, tableAlias.TableName)
-			buf.WriteByte('.')
+		} else {
+			buf.WriteString("_.")
 		}
 	}
 	buf.WriteString(src.sourceColumns[colIdx].Name)