Add more docs

.gitignore

@@ -1 +1,2 @@
-.pgsql/data
+.pgsql/data
+bin

Makefile

@@ -15,3 +15,7 @@ is-postgres-running:
 .PHONY: pgweb
 pgweb:is-postgres-running
 	@pgweb --url "postgres://test_source@localhost:5432/test_source?sslmode=disable"
+
+
+build:
+	CGO_ENABLEd=0 go build -o bin/subsetter ${PACKAGE}/cli

README.md

@@ -17,6 +17,19 @@ Utilizing the native PostgreSQL COPY command, pg-subsetter performs data transfe
 
 ## Usage
 
+```
+Usage of subsetter:
+  -dst string
+        Destination DSN
+  -f float
+        Fraction of rows to copy (default 0.05)
+  -src string
+        Source DSN
+```
+
+
+Example:
+
 ```pg-subsetter -src postgresql://:@/bigdb -dst postgresql://:@/littledb -f 0.05```
 
 # Installing

cli/main.go

@@ -6,12 +6,20 @@ import (
 	"github.com/rs/zerolog/log"
 )
 
-var src = flag.String("src", "", "Source DSN")
-var dst = flag.String("dst", "", "Destination DSN")
-var fraction = flag.Float64("f", 1.0, "Fraction of rows to copy")
+var src = flag.String("src", "", "Source database DSN")
+var dst = flag.String("dst", "", "Destination database DSN")
+var fraction = flag.Float64("f", 0.05, "Fraction of rows to copy")
 
 func main() {
 	flag.Parse()
 	log.Info().Msg("Starting")
 
+	if *src == "" || *dst == "" {
+		log.Fatal().Msg("Source and destination DSNs are required")
+	}
+
+	if *fraction <= 0 || *fraction > 1 {
+		log.Fatal().Msg("Fraction must be between 0 and 1")
+	}
+
 }

subsetter/db_test.go

@@ -41,8 +41,7 @@ func populateTestsWithData(conn *pgx.Conn, table string, size int) {
 	for i := 0; i < size; i++ {
 		query := fmt.Sprintf("INSERT INTO %s (text) VALUES ('test%d') RETURNING id", table, i)
 		var row string
-		err := conn.QueryRow(context.Background(), query).Scan(&row)
-		fmt.Println(err)
+		conn.QueryRow(context.Background(), query).Scan(&row)
 		query = fmt.Sprintf("INSERT INTO relation (simple_id) VALUES ('%v')", row)
 
 		conn.Exec(context.Background(), query)