From 54c6dfc05c5ca5d88a4f2b23ad7a8914832e855c Mon Sep 17 00:00:00 2001 From: Max Englander Date: Fri, 16 Feb 2024 13:05:01 -0500 Subject: [PATCH] queryserving, observability: instrument vttablet query cache plan hits/misses (#14947) Signed-off-by: Max Englander Signed-off-by: Florent Poinsard Co-authored-by: Florent Poinsard --- changelog/20.0/20.0.0/summary.md | 12 ++++++++++-- go/vt/vttablet/tabletserver/query_engine.go | 7 +++++++ go/vt/vttablet/tabletserver/query_engine_test.go | 16 ++++++++++++++++ 3 files changed, 33 insertions(+), 2 deletions(-) diff --git a/changelog/20.0/20.0.0/summary.md b/changelog/20.0/20.0.0/summary.md index 54179429bd5..bb376c6e721 100644 --- a/changelog/20.0/20.0.0/summary.md +++ b/changelog/20.0/20.0.0/summary.md @@ -11,11 +11,11 @@ - **[Flag changes](#flag-changes)** - [`pprof-http` default change](#pprof-http-default) - **[Minor Changes](#minor-changes)** - + - **[New Stats](#new-stats)** + - [VTTablet Query Cache Hits and Misses](#vttablet-query-cache-hits-and-misses) ## Major Changes - ### Query Compatibility #### Vindex Hints @@ -64,3 +64,11 @@ To continue enabling these endpoints, explicitly set `--pprof-http` when startin ## Minor Changes +### New Stats + +#### VTTablet Query Cache Hits and Misses + +VTTablet exposes two new counter stats: + + * `QueryCacheHits`: Query engine query cache hits + * `QueryCacheMisses`: Query engine query cache misses diff --git a/go/vt/vttablet/tabletserver/query_engine.go b/go/vt/vttablet/tabletserver/query_engine.go index b87c5cf97ba..f009a72ceee 100644 --- a/go/vt/vttablet/tabletserver/query_engine.go +++ b/go/vt/vttablet/tabletserver/query_engine.go @@ -188,6 +188,7 @@ type QueryEngine struct { // stats // Note: queryErrorCountsWithCode is similar to queryErrorCounts except it contains error code as an additional dimension queryCounts, queryCountsWithTabletType, queryTimes, queryErrorCounts, queryErrorCountsWithCode, queryRowsAffected, queryRowsReturned *stats.CountersWithMultiLabels + queryCacheHits, queryCacheMisses *stats.CounterFunc // stats flags enablePerWorkloadTableMetrics bool @@ -280,6 +281,12 @@ func NewQueryEngine(env tabletenv.Env, se *schema.Engine) *QueryEngine { env.Exporter().NewCounterFunc("QueryCacheEvictions", "Query engine query cache evictions", func() int64 { return qe.plans.Metrics.Evicted() }) + qe.queryCacheHits = env.Exporter().NewCounterFunc("QueryCacheHits", "Query engine query cache hits", func() int64 { + return qe.plans.Metrics.Hits() + }) + qe.queryCacheMisses = env.Exporter().NewCounterFunc("QueryCacheMisses", "Query engine query cache misses", func() int64 { + return qe.plans.Metrics.Misses() + }) labels := []string{"Table", "Plan"} if config.EnablePerWorkloadTableMetrics { diff --git a/go/vt/vttablet/tabletserver/query_engine_test.go b/go/vt/vttablet/tabletserver/query_engine_test.go index 8dbe18ef13c..604f65f3311 100644 --- a/go/vt/vttablet/tabletserver/query_engine_test.go +++ b/go/vt/vttablet/tabletserver/query_engine_test.go @@ -186,11 +186,27 @@ func TestQueryPlanCache(t *testing.T) { ctx := context.Background() logStats := tabletenv.NewLogStats(ctx, "GetPlanStats") + initialHits := qe.queryCacheHits.Get() + initialMisses := qe.queryCacheMisses.Get() + firstPlan, err := qe.GetPlan(ctx, logStats, firstQuery, false) require.NoError(t, err) require.NotNil(t, firstPlan, "plan should not be nil") assertPlanCacheSize(t, qe, 1) + + require.Equal(t, int64(0), qe.queryCacheHits.Get()-initialHits) + require.Equal(t, int64(1), qe.queryCacheMisses.Get()-initialMisses) + + secondPlan, err := qe.GetPlan(ctx, logStats, firstQuery, false) + require.NoError(t, err) + require.NotNil(t, secondPlan, "plan should not be nil") + + assertPlanCacheSize(t, qe, 1) + + require.Equal(t, int64(1), qe.queryCacheHits.Get()-initialHits) + require.Equal(t, int64(1), qe.queryCacheMisses.Get()-initialMisses) + qe.ClearQueryPlanCache() }