Revert "Reordering columns"

Column reordering is broken. 😢

This reverts commit be87768.

.gitignore

@@ -1,7 +1,3 @@
 private-data
 verticat
 xxx.bin
-reo1.txt
-avtr.txt
-avt.txt
-verticareader

README.md

@@ -10,89 +10,27 @@ from  [Vertica native binary files](https://www.vertica.com/docs/9.3.x/HTML/Cont
 ## Usage
 
 ```bash
-Usage: verticat [-cfHpv] [-h value] [-o value] [-r value] [-t value] [file...]
+Usage: verticat [-cfHv] [-h value] [-o value] [-t value] [file...]
  -c, --count       count rows
  -f, --force       force overwrite of output file
  -h, --head=value  take the first n rows
  -H, --help        show help
  -o, --output=value
                    write head/tail results to this file
- -p, --print-header
-                   print out header and exit
- -r, --reorder=value
-                   reorder columns based on this file
  -t, --tail=value  take the last n rows
  -v, --version     show version
 ```
 
-## Options
+Running with `--count` will print out the number of data rows in the file(s). The header does not count as a row.
 
-`--count` or `-c` will print out the number of data rows in the file(s). 
-The header does not count as a row.
+Running with `--head` or `--tail` will copy the first `n` rows, or the last `n` rows, respectively, to the output. When
+either is used with multiple files, `n` rows will be taken from each file, and written to the output.
 
-`--force`, or `-f` will overwrite an output file, if it exists.
+If `--output` is not specified, `stdout` is used. Be careful with this, since binary data echoed to the console may be
+undesirable.
 
-`--head`, or `-h` copies the first `n` rows of the given file(s). If multiple files are
-given, they must all have an identical layout, as the header of the first will be 
-copied with all of the output.
+If combining multiple files with `--head`, `--tail`, or no options, they must all share the same column layout.
 
-`--help`, or `-H` prints usage information.
-
-`--output`, or `-o` gives a filename to send the output to. If this is not specified,
-output goes to `stdout`.
-
-`--print-header`, or `-p` will print the list of column widths, in order, and exit.
-
-`--reorder`, or `-r`, specifies a file with the the desired column reordering. The 
-indices can be separated by any sort of whitespace (spaces, tabs, newslines, etc.).
-
-`--tail`, or `-t`, copies the last `n` rows of the given file(s). As with `--head`, 
-if multiple files are given, they must all have an identical layout, as the header 
-of the first will be copied with all of the output.
-
-`--version`, or `-v` display the program version.
-
-## Notes
-
-If no filenames are given, `verticat` acts like the standard `cat` program, reading 
-from `stdin`. **This only works with a single file**, since Vertica native files
-have a header. If you need to combine multiple files, give them as arguments to the
-program itself.
-
-## Examples
-
-To read the first 5 lines of `foo.bin`, and write the output to `bar.bin`,
-
-```bash
-verticat --head 5 -o bar.bin foo.bin
-```
-
-To read the last 5 lines of `foo.bin`, and write the output to `bar.bin`,
-
-```bash
-verticat --tail 5 -o bar.bin foo.bin
-```
-
-To read the first 5 lines of `foo.bin`, `bar.bin`, and `baz.bin`, and write the
-output to `quux.bin`
-
-```bash
-verticat --head 5 -o quux.bin foo.bin bar.bin baz.bin
-```
-
-To combine all of `foo.bin` and `bar.bin` and write the output to `baz.bin`
-
-```bash
-verticat -o baz.bin foo.bin bar.bin
-```
-
-To reorder `foo.bin` using the ordering specified in `reo.txt`, and write to `stdout`.
-In this example, the first five columns will be written in reverse order, and the final 
-four in their original order. 
-
-```bash
-$> cat reo.txt
-5, 4, 3, 2, 1, 6, 7, 8, 9
-
-$> verticat -r reo.txt foo.bin
-```
+If no options are given, `verticat` acts like the standard `cat` program, reading from `stdin` if no files are given. Since
+Vertica native files start with a metadata header, if you want to cat multiple files together, specify them as arguments
+to `verticat` itself.

lib/column_definitions.go

@@ -12,7 +12,6 @@ type ColumnDefinitions struct {
 	Filler          byte
 	NumberOfColumns uint16
 	Widths          []uint32
-	NewColumnOrder  []uint
 }
 
 func (c ColumnDefinitions) Write(file io.Writer) (err error) {
@@ -36,29 +35,15 @@ func (c ColumnDefinitions) Write(file io.Writer) (err error) {
 		return
 	}
 
-	if c.NewColumnOrder == nil {
-		err = binary.Write(file, binary.LittleEndian, c.Widths)
-		if err != nil {
-			return
-		}
-	} else {
-		// Re-order the column widths based on the specified order
-		orderedWidths := make([]uint32, len(c.Widths))
-
-		for i, val := range c.NewColumnOrder {
-			orderedWidths[i] = c.Widths[val - 1]
-		}
-
-		err = binary.Write(file, binary.LittleEndian, orderedWidths)
-		if err != nil {
-			return
-		}
+	err = binary.Write(file, binary.LittleEndian, c.Widths)
+	if err != nil {
+		return
 	}
 
 	return nil
 }
 
-func ReadColumnDefinitions(file *os.File, newColumnOrder []uint) (ColumnDefinitions, error) {
+func ReadColumnDefinitions(file *os.File) (ColumnDefinitions, error) {
 	var headerLength uint32
 	var version uint16
 	var filler byte
@@ -97,7 +82,6 @@ func ReadColumnDefinitions(file *os.File, newColumnOrder []uint) (ColumnDefiniti
 		Filler:          filler,
 		NumberOfColumns: numberOfColumns,
 		Widths:          widths,
-		NewColumnOrder: newColumnOrder,
 	}
 
 	return definitions, nil

lib/column_definitions_test.go

@@ -22,7 +22,7 @@ func TestReadColumnDefinitions(t *testing.T) {
 		t.Fatal("signature didn't match")
 	}
 
-	definitions, err := ReadColumnDefinitions(file, nil)
+	definitions, err := ReadColumnDefinitions(file)
 	if err != nil {
 		t.Fatal("error reading column definitions: ", err)
 	}