Add migrations to vacuum internal database

Author: dpordomingo

cli/migrations/README.md

@@ -4,6 +4,12 @@ These scripts are <u>**not real migrations**</u>. There is no up/down rules. The
 
 These scripts were needed to migrate the Database between different states.
 
+- [Vacuum database](command-vacuum.go)
+```shell
+# rebuilds the database to defragment it
+go run cli/migrations/*.go vacuum internal.db
+```
+
 - [Add UAST nullable columns](command-UAST-add-columns.go)
 ```shell
 # prepares the current "internal.db". Adds "uast_a" and "uast_b" nulable cols

cli/migrations/command-vacuum.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/src-d/code-annotation/server/dbutil"
+)
+
+type vacuumCmd struct {
+	commandDesc
+	Args struct {
+		InternalDBPath string `description:"filepath to the internal SQLite database"`
+	} `positional-args:"yes" required:"yes"`
+}
+
+var vacuumOpts = vacuumCmd{
+	commandDesc: commandDesc{
+		name:      "vacuum",
+		shortDesc: "Rebuilds the database to defragment it",
+		longDesc:  "Rebuilds the sqlite://InternalDBPath database to eliminate free pages, compact table data...",
+	},
+}
+
+// queries
+const (
+	vacuumQuery = "VACUUM"
+)
+
+func (c *vacuumCmd) Execute(args []string) error {
+	internalDb, err := dbutil.Open(fmt.Sprintf(sqliteDSN, c.Args.InternalDBPath), false)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	defer internalDb.Close()
+
+	log.Println("Running VACUUM process ...")
+
+	_, err = internalDb.Exec(vacuumQuery)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	log.Println("... VACUUM process finished")
+	return nil
+}

cli/migrations/main.go

@@ -18,6 +18,7 @@ func main() {
 	addCommand(parser, &uastColsOpts)
 	addCommand(parser, &uastImportOpts)
 	addCommand(parser, &diffRmColOpts)
+	addCommand(parser, &vacuumOpts)
 	parse(parser, description)
 }