sql: add full table or index scan count to metrics

This new metric allows for users to see a time series of their full table
or index scans in the advanced debug console. This metric is part of
EngineMetrics, so there's a corresponding internal metric that counts
internal full table or index scans from internal engine queries.

Release note (ui change): User can see time series of full table or index
scans in advanced debug console.

pkg/sql/conn_executor.go

@@ -31,6 +31,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/descpb"
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/descs"
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/tabledesc"
+	"github.com/cockroachdb/cockroach/pkg/sql/execinfra"
 	"github.com/cockroachdb/cockroach/pkg/sql/parser"
 	"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgcode"
 	"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgerror"
@@ -301,7 +302,6 @@ func makeMetrics(internal bool) Metrics {
 			SQLOptFallbackCount:   metric.NewCounter(getMetricMeta(MetaSQLOptFallback, internal)),
 			SQLOptPlanCacheHits:   metric.NewCounter(getMetricMeta(MetaSQLOptPlanCacheHits, internal)),
 			SQLOptPlanCacheMisses: metric.NewCounter(getMetricMeta(MetaSQLOptPlanCacheMisses, internal)),
-
 			// TODO(mrtracy): See HistogramWindowInterval in server/config.go for the 6x factor.
 			DistSQLExecLatency: metric.NewLatency(getMetricMeta(MetaDistSQLExecLatency, internal),
 				6*metricsSampleInterval),
@@ -315,8 +315,9 @@ func makeMetrics(internal bool) Metrics {
 				6*metricsSampleInterval),
 			SQLTxnsOpen: metric.NewGauge(getMetricMeta(MetaSQLTxnsOpen, internal)),
 
-			TxnAbortCount: metric.NewCounter(getMetricMeta(MetaTxnAbort, internal)),
-			FailureCount:  metric.NewCounter(getMetricMeta(MetaFailure, internal)),
+			TxnAbortCount:             metric.NewCounter(getMetricMeta(MetaTxnAbort, internal)),
+			FailureCount:              metric.NewCounter(getMetricMeta(MetaFailure, internal)),
+			FullTableOrIndexScanCount: metric.NewCounter(getMetricMeta(MetaFullTableOrIndexScan, internal)),
 		},
 		StartedStatementCounters:  makeStartedStatementCounters(internal),
 		ExecutedStatementCounters: makeExecutedStatementCounters(internal),
@@ -566,7 +567,6 @@ func (s *Server) newConnExecutor(
 	nodeIDOrZero, _ := s.cfg.NodeID.OptionalNodeID()
 	sdMutator := new(sessionDataMutator)
 	*sdMutator = s.makeSessionDataMutator(sd, sdDefaults)
-
 	ex := &connExecutor{
 		server:      s,
 		metrics:     srvMetrics,

pkg/sql/conn_executor_exec.go

@@ -914,17 +914,19 @@ func (ex *connExecutor) makeExecPlan(ctx context.Context, planner *planner) erro
 
 	flags := planner.curPlan.flags
 
-	// We don't execute the statement if:
-	// - plan contains a full table or full index scan.
-	// - the session setting disallows full table/index scans.
-	// - the query is not an internal query.
-	if (flags.IsSet(planFlagContainsFullIndexScan) || flags.IsSet(planFlagContainsFullTableScan)) &&
-		planner.EvalContext().SessionData.DisallowFullTableScans && ex.executorType == executorTypeExec {
-		return errors.WithHint(
-			pgerror.Newf(pgcode.TooManyRows,
-				"query `%s` contains a full table/index scan which is explicitly disallowed",
-				planner.stmt.SQL),
-			"try overriding the `disallow_full_table_scans` cluster/session setting")
+	if flags.IsSet(planFlagContainsFullIndexScan) || flags.IsSet(planFlagContainsFullTableScan) {
+		if ex.executorType == executorTypeExec && planner.EvalContext().SessionData.DisallowFullTableScans {
+			// We don't execute the statement if:
+			// - plan contains a full table or full index scan.
+			// - the session setting disallows full table/index scans.
+			// - the query is not an internal query.
+			return errors.WithHint(
+				pgerror.Newf(pgcode.TooManyRows,
+					"query `%s` contains a full table/index scan which is explicitly disallowed",
+					planner.stmt.SQL),
+				"try overriding the `disallow_full_table_scans` cluster/session setting")
+		}
+		ex.metrics.EngineMetrics.FullTableOrIndexScanCount.Inc(1)
 	}
 
 	// TODO(knz): Remove this accounting if/when savepoint rollbacks

pkg/sql/exec_util.go

@@ -488,9 +488,14 @@ var (
 		Measurement: "Open SQL Transactions",
 		Unit:        metric.Unit_COUNT,
 	}
+	MetaFullTableOrIndexScan = metric.Metadata{
+		Name:        "sql.full.scan.count",
+		Help:        "Number of full table or index scans",
+		Measurement: "SQL Statements",
+		Unit:        metric.Unit_COUNT,
+	}
 
 	// Below are the metadata for the statement started counters.
-
 	MetaQueryStarted = metric.Metadata{
 		Name:        "sql.query.started.count",
 		Help:        "Number of SQL queries started",

pkg/sql/executor_statement_metrics.go

@@ -140,6 +140,9 @@ type EngineMetrics struct {
 
 	// FailureCount counts non-retriable errors in open transactions.
 	FailureCount *metric.Counter
+
+	// FullTableOrIndexScanCount counts the number of full table or index scans.
+	FullTableOrIndexScanCount *metric.Counter
 }
 
 // EngineMetrics implements the metric.Struct interface