go-delta - A Go package and utility to generate and apply binary delta updates.
Suggestions:
-
Works best on text files, database dumps and any other files with lots of repeating patterns and few changes between updates.
-
Generating deltas of compressed files is not recommended because a small change in the source data can lead to lots of changes in the compressed result, so generating a delta update may give you only minimal size reduction.
-
Don't compress bytes returned by Delta.Bytes() because they are already compressed using ZLib compression.
-
Every delta update adds about 156 bytes for the source and target hashes and various lengths, so it is not recommended for very miniscule updates.
Demonstration:
package main
import (
"fmt"
"github.com/balacode/go-delta"
)
func main() {
fmt.Print("Binary delta update demo:\n\n")
// The original data (20 bytes):
var source = []byte("quick brown fox, lazy dog, and five boxing wizards")
fmt.Print("The original is:", "\n", string(source), "\n\n")
// The updated data containing the original and new content (82 bytes):
var target = []byte(
"The quick brown fox jumps over the lazy dog. " +
"The five boxing wizards jump quickly.",
)
fmt.Print("The update is:", "\n", string(target), "\n\n")
var dbytes []byte
{
// Use Make() to generate a compressed patch from source and target
var d = delta.Make(source, target)
// Convert the delta to a slice of bytes (e.g. for writing to a file)
dbytes = d.Bytes()
}
// Create a Delta from the byte slice
var d = delta.Load(dbytes)
// Apply the patch to source to get the target
// The size of the patch is much shorter than target.
var target2, err = d.Apply(source)
if err != nil {
fmt.Println(err)
}
fmt.Print("Patched:", "\n", string(target2), "\n\n")
} // main