From db2be9f119a979b934cefa674cefecbf27ab07ca Mon Sep 17 00:00:00 2001
From: Sugu Sougoumarane <sougou@google.com>
Date: Tue, 27 Mar 2012 12:19:39 -0700
Subject: [PATCH] skip pk row cache optimization if there's an order by clause
 display query plans for query_cache stats rowcache: limit size to 4k

---
 go/vt/sqlparser/execution.go        | 24 +++++++++++++-----------
 go/vt/sqlparser/test/exec_cases.txt | 23 +++++++++++++++++++++++
 go/vt/tabletserver/rowcache.go      | 21 +++++++++++++++++++++
 go/vt/tabletserver/schema_info.go   | 13 ++++++++++++-
 4 files changed, 69 insertions(+), 12 deletions(-)

diff --git a/go/vt/sqlparser/execution.go b/go/vt/sqlparser/execution.go
index 7440fddefa..6279f2c7b7 100644
--- a/go/vt/sqlparser/execution.go
+++ b/go/vt/sqlparser/execution.go
@@ -265,26 +265,28 @@ func (self *Node) execAnalyzeSelect(getTable TableGetter) (plan *ExecPlan) {
 		return plan
 	}
 
-	if pkValues := getPKValues(conditions, tableInfo.Indexes[0]); pkValues != nil {
-		plan.PlanId = PLAN_SELECT_PK
-		plan.OuterQuery = self.GenerateSelectOuterQuery(tableInfo)
-		plan.PKValues = pkValues
+	// order
+	orders := self.At(SELECT_ORDER_OFFSET).execAnalyzeOrder()
+	if orders == nil {
+		plan.Reason = REASON_ORDER
 		return plan
 	}
 
+	if len(orders) == 0 { // Only do pk analysis if there's no order by clause
+		if pkValues := getPKValues(conditions, tableInfo.Indexes[0]); pkValues != nil {
+			plan.PlanId = PLAN_SELECT_PK
+			plan.OuterQuery = self.GenerateSelectOuterQuery(tableInfo)
+			plan.PKValues = pkValues
+			return plan
+		}
+	}
+
 	// TODO: Analyze hints to improve plan.
 	if hasHints {
 		plan.Reason = REASON_HAS_HINTS
 		return plan
 	}
 
-	// order
-	orders := self.At(SELECT_ORDER_OFFSET).execAnalyzeOrder()
-	if orders == nil {
-		plan.Reason = REASON_ORDER
-		return plan
-	}
-
 	plan.IndexUsed = getIndexMatch(conditions, orders, tableInfo.Indexes)
 	if plan.IndexUsed == "" {
 		plan.Reason = REASON_NOINDEX_MATCH
diff --git a/go/vt/sqlparser/test/exec_cases.txt b/go/vt/sqlparser/test/exec_cases.txt
index cd9a1bf532..432b112884 100644
--- a/go/vt/sqlparser/test/exec_cases.txt
+++ b/go/vt/sqlparser/test/exec_cases.txt
@@ -829,6 +829,29 @@ select * from a where eid between 1 and 2 and name='foo'
   "SetValue": null
 }
 
+# order by (pk)
+select * from a where eid=1 and id=1 order by name
+{
+  "PlanId": "SELECT_CACHE_RESULT",
+  "Reason": "PKINDEX",
+  "TableName": "a",
+  "FullQuery": "select * from a where eid = 1 and id = 1 order by name asc limit :_vtMaxResultSize",
+  "OuterQuery": "select eid, id, name, foo from a where eid = 1 and id = 1 order by name asc limit :_vtMaxResultSize",
+  "Subquery": null,
+  "IndexUsed": "PRIMARY",
+  "ColumnNumbers": [
+    0,
+    1,
+    2,
+    3
+  ],
+  "PKValues": null,
+  "SecondaryPKValues": null,
+  "SubqueryPKColumns": null,
+  "SetKey": "",
+  "SetValue": null
+}
+
 # order by
 select * from a where eid=1 order by name
 {
diff --git a/go/vt/tabletserver/rowcache.go b/go/vt/tabletserver/rowcache.go
index 43059838cc..3ee354f662 100644
--- a/go/vt/tabletserver/rowcache.go
+++ b/go/vt/tabletserver/rowcache.go
@@ -75,6 +75,11 @@ func (self *RowCache) Get(key string) (row []interface{}) {
 }
 
 func (self *RowCache) Set(key string, row []interface{}, readTime time.Time) {
+	// This value is hardcoded for now.
+	// We're assuming it's not worth caching rows that are too large.
+	if rowLen(row) > 4000 {
+		return
+	}
 	conn := self.cachePool.Get()
 	defer conn.Recycle()
 	mkey := self.prefix + key
@@ -117,3 +122,19 @@ func (self *RowCache) Delete(key string) {
 		panic(NewTabletError(FATAL, "%s", err))
 	}
 }
+
+func rowLen(row []interface{}) int {
+	length := 0
+	for _, v := range row {
+		if v == nil {
+			continue
+		}
+		switch col := v.(type) {
+		case string:
+			length += len(col)
+		case []byte:
+			length += len(col)
+		}
+	}
+	return length
+}
diff --git a/go/vt/tabletserver/schema_info.go b/go/vt/tabletserver/schema_info.go
index 211304312c..08c4968cb3 100644
--- a/go/vt/tabletserver/schema_info.go
+++ b/go/vt/tabletserver/schema_info.go
@@ -36,6 +36,7 @@ import (
 	"code.google.com/p/vitess/go/relog"
 	"code.google.com/p/vitess/go/vt/schema"
 	"code.google.com/p/vitess/go/vt/sqlparser"
+	"encoding/json"
 	"fmt"
 	"net/http"
 	"sync"
@@ -202,8 +203,16 @@ func (self *SchemaInfo) ServeHTTP(response http.ResponseWriter, request *http.Re
 		response.Write([]byte(fmt.Sprintf("Length: %d\n", len(keys))))
 		for _, v := range keys {
 			response.Write([]byte(fmt.Sprintf("%s\n", v)))
+			if plan := self.getQuery(v); plan != nil {
+				if b, err := json.MarshalIndent(plan, "", "  "); err != nil {
+					response.Write([]byte(err.Error()))
+				} else {
+					response.Write(b)
+					response.Write(([]byte)("\n\n"))
+				}
+			}
 		}
-	} else { // tables
+	} else if request.URL.Path == "/debug/schema/tables" {
 		response.Header().Set("Content-Type", "text/plain")
 		self.mu.Lock()
 		tstats := make(map[string]struct{ hits, absent, misses int64 })
@@ -224,5 +233,7 @@ func (self *SchemaInfo) ServeHTTP(response http.ResponseWriter, request *http.Re
 		}
 		fmt.Fprintf(response, "\"Totals\": {\"Hits\": %v, \"Absent\": %v, \"Misses\": %v}\n", totals.hits, totals.absent, totals.misses)
 		response.Write([]byte("}\n"))
+	} else {
+		response.WriteHeader(http.StatusNotFound)
 	}
 }