limit mapreduce table output to 10 rows by default

4 files changed, 23 insertions, 7 deletions

diff --git a/TODO.md b/TODO.md
index 189a516..4c60e4c 100644
--- a/TODO.md
+++ b/TODO.md
@@ -10,6 +10,7 @@ This is a loose list of what to do. Maybe for the next releae or maybe for a lat
 [x] Paint ^CLIENT messages (e.g. use yellow backgrounds here)
 [x] Paint ^SERVER messages (e.g. use cyan backgrounds here)
 [x] Adjust dmap with color schemas
+[x] Auto limit stdout map output to 10 results.
 [ ] Fix JSONSchema for the colors
 [ ] Implement Benchmark cat-ing a file and compare to prev version.
 [?] Client 4.x should print a warning when trying to connect to a 3.x server.
diff --git a/internal/clients/maprclient.go b/internal/clients/maprclient.go
index cab9a6c..2cad15d 100644
--- a/internal/clients/maprclient.go
+++ b/internal/clients/maprclient.go
@@ -158,12 +158,18 @@ func (c *MaprClient) reportResults() {
 func (c *MaprClient) printResults() {
 	var result string
 	var err error
-	var numRows int
+	var numRows, rowsLimit int
+
+	if c.query.Limit == -1 {
+		// Limit output to 10 rows when the result is printed to stdout.
+		// This can be overriden with the limit clause though.
+		rowsLimit = 10
+	}
 
 	if c.cumulative {
-		result, numRows, err = c.globalGroup.Result(c.query)
+		result, numRows, err = c.globalGroup.Result(c.query, rowsLimit)
 	} else {
-		result, numRows, err = c.globalGroup.SwapOut().Result(c.query)
+		result, numRows, err = c.globalGroup.SwapOut().Result(c.query, rowsLimit)
 	}
 
 	if err != nil {
@@ -189,6 +195,11 @@ func (c *MaprClient) printResults() {
 			config.Client.TermColors.MaprTable.RawQueryAttr)
 	}
 	logger.Raw(rawQuery)
+
+	if rowsLimit > 0 && numRows > rowsLimit {
+		logger.Warn(fmt.Sprintf("Got %d results but limited output to %d rows! Use 'limit' clause to override!",
+			numRows, rowsLimit))
+	}
 	logger.Raw(result)
 }
 
diff --git a/internal/mapr/globalgroupset.go b/internal/mapr/globalgroupset.go
index 21bf990..50bac37 100644
--- a/internal/mapr/globalgroupset.go
+++ b/internal/mapr/globalgroupset.go
@@ -93,9 +93,9 @@ func (g *GlobalGroupSet) WriteResult(query *Query) error {
 }
 
 // Result returns the result of the mapreduce aggregation as a string.
-func (g *GlobalGroupSet) Result(query *Query) (string, int, error) {
+func (g *GlobalGroupSet) Result(query *Query, rowsLimit int) (string, int, error) {
 	g.semaphore <- struct{}{}
 	defer func() { <-g.semaphore }()
 
-	return g.GroupSet.Result(query)
+	return g.GroupSet.Result(query, rowsLimit)
 }
diff --git a/internal/mapr/groupset.go b/internal/mapr/groupset.go
index d29559a..9bff790 100644
--- a/internal/mapr/groupset.go
+++ b/internal/mapr/groupset.go
@@ -68,12 +68,16 @@ func (g *GroupSet) Serialize(ctx context.Context, ch chan<- string) {
 }
 
 // Result returns a nicely formated result of the query from the group set.
-func (g *GroupSet) Result(query *Query) (string, int, error) {
+func (g *GroupSet) Result(query *Query, rowsLimit int) (string, int, error) {
 	rows, widths, err := g.result(query, true)
 	if err != nil {
 		return "", 0, err
 	}
 
+	if query.Limit != -1 {
+		rowsLimit = query.Limit
+	}
+
 	sb := pool.BuilderBuffer.Get().(*strings.Builder)
 	defer pool.RecycleBuilderBuffer(sb)
 
@@ -141,7 +145,7 @@ func (g *GroupSet) Result(query *Query) (string, int, error) {
 
 	// And now write the data
 	for i, r := range rows {
-		if i == query.Limit {
+		if i == rowsLimit {
 			break
 		}
 		for j, value := range r.values {