Implement rollup resolution decider for incoming queries.

Signed-off-by: Harkishen-Singh <harkishensingh@hotmail.com>

pkg/dataset/config.go

@@ -50,7 +50,7 @@ type Metrics struct {
 	HALeaseRefresh  day.Duration   `yaml:"ha_lease_refresh"`
 	HALeaseTimeout  day.Duration   `yaml:"ha_lease_timeout"`
 	RetentionPeriod day.Duration   `yaml:"default_retention_period"`
-	Rollups         *rollup.Config `yaml:"rollups,omitempty"`
+	Rollup          *rollup.Config `yaml:"rollup,omitempty"`
 }
 
 // Traces contains dataset configuration options for traces data.
@@ -68,8 +68,8 @@ func NewConfig(contents string) (cfg Config, err error) {
 func (c *Config) Apply(ctx context.Context, conn *pgx.Conn) error {
 	c.applyDefaults()
 
-	if c.Metrics.Rollups != nil {
-		if err := c.Metrics.Rollups.Apply(ctx, conn); err != nil {
+	if c.Metrics.Rollup != nil {
+		if err := c.Metrics.Rollup.Apply(ctx, conn); err != nil {
 			return fmt.Errorf("error applying configuration for downsampling: %w", err)
 		}
 	}

pkg/pgclient/client.go

@@ -61,7 +61,7 @@ type Client struct {
 }
 
 // NewClient creates a new PostgreSQL client
-func NewClient(r prometheus.Registerer, cfg *Config, mt tenancy.Authorizer, schemaLocker LockFunc, readOnly bool) (*Client, error) {
+func NewClient(r prometheus.Registerer, cfg *Config, mt tenancy.Authorizer, schemaLocker LockFunc, readOnly, useRollups bool) (*Client, error) {
 	var (
 		err            error
 		dbMaxConns     int
@@ -137,7 +137,7 @@ func NewClient(r prometheus.Registerer, cfg *Config, mt tenancy.Authorizer, sche
 	if err != nil {
 		return nil, fmt.Errorf("err creating reader connection pool: %w", err)
 	}
-	client, err := NewClientWithPool(r, cfg, numCopiers, writerPool, readerPool, maintPool, mt, readOnly)
+	client, err := NewClientWithPool(r, cfg, numCopiers, writerPool, readerPool, maintPool, mt, readOnly, useRollups)
 	if err != nil {
 		return client, err
 	}
@@ -197,7 +197,7 @@ func getRedactedConnStr(s string) string {
 }
 
 // NewClientWithPool creates a new PostgreSQL client with an existing connection pool.
-func NewClientWithPool(r prometheus.Registerer, cfg *Config, numCopiers int, writerPool, readerPool, maintPool *pgxpool.Pool, mt tenancy.Authorizer, readOnly bool) (*Client, error) {
+func NewClientWithPool(r prometheus.Registerer, cfg *Config, numCopiers int, writerPool, readerPool, maintPool *pgxpool.Pool, mt tenancy.Authorizer, readOnly, useRollups bool) (*Client, error) {
 	sigClose := make(chan struct{})
 	metricsCache := cache.NewMetricCache(cfg.CacheConfig)
 	labelsCache := cache.NewLabelsCache(cfg.CacheConfig)
@@ -223,7 +223,11 @@ func NewClientWithPool(r prometheus.Registerer, cfg *Config, numCopiers int, wri
 	exemplarKeyPosCache := cache.NewExemplarLabelsPosCache(cfg.CacheConfig)
 
 	labelsReader := lreader.NewLabelsReader(readerConn, labelsCache, mt.ReadAuthorizer())
-	dbQuerier := querier.NewQuerier(readerConn, metricsCache, labelsReader, exemplarKeyPosCache, mt.ReadAuthorizer())
+	dbQuerier, err := querier.NewQuerier(readerConn, metricsCache, labelsReader, exemplarKeyPosCache, mt.ReadAuthorizer(), cfg.MetricsScrapeInterval, useRollups)
+	if err != nil {
+		return nil, fmt.Errorf("error starting querier: %w", err)
+	}
+
 	queryable := query.NewQueryable(dbQuerier, labelsReader)
 
 	dbIngestor := ingestor.DBInserter(ingestor.ReadOnlyIngestor{})
@@ -232,8 +236,7 @@ func NewClientWithPool(r prometheus.Registerer, cfg *Config, numCopiers int, wri
 		writerConn = pgxconn.NewPgxConn(writerPool)
 		dbIngestor, err = ingestor.NewPgxIngestor(writerConn, metricsCache, seriesCache, exemplarKeyPosCache, &c)
 		if err != nil {
-			log.Error("msg", "err starting the ingestor", "err", err)
-			return nil, err
+			return nil, fmt.Errorf("error starting ingestor: %w", err)
 		}
 	}
 	if maintPool != nil {

pkg/pgclient/config.go

@@ -18,6 +18,7 @@ import (
 	"github.com/timescale/promscale/pkg/log"
 	"github.com/timescale/promscale/pkg/pgmodel/cache"
 	"github.com/timescale/promscale/pkg/pgmodel/ingestor/trace"
+	"github.com/timescale/promscale/pkg/rollup"
 	"github.com/timescale/promscale/pkg/version"
 )
 
@@ -34,6 +35,7 @@ type Config struct {
 	DbConnectionTimeout     time.Duration
 	IgnoreCompressedChunks  bool
 	MetricsAsyncAcks        bool
+	MetricsScrapeInterval   time.Duration
 	TracesAsyncAcks         bool
 	WriteConnections        int
 	WriterPoolSize          int
@@ -107,6 +109,7 @@ func ParseFlags(fs *flag.FlagSet, cfg *Config) *Config {
 	fs.IntVar(&cfg.TracesMaxBatchSize, "tracing.max-batch-size", trace.DefaultBatchSize, "Maximum size of trace batch that is written to DB")
 	fs.DurationVar(&cfg.TracesBatchTimeout, "tracing.batch-timeout", trace.DefaultBatchTimeout, "Timeout after new trace batch is created")
 	fs.IntVar(&cfg.TracesBatchWorkers, "tracing.batch-workers", trace.DefaultBatchWorkers, "Number of workers responsible for creating trace batches. Defaults to number of CPUs.")
+	fs.DurationVar(&cfg.MetricsScrapeInterval, "metrics.rollup.scrape-interval", rollup.DefaultScrapeInterval, "Default scrape interval in Prometheus. This is used to estimate samples while choosing rollup for querying.")
 	return cfg
 }
 

pkg/pgmodel/querier/querier.go

@@ -6,17 +6,21 @@ package querier
 
 import (
 	"context"
+	"fmt"
+	"time"
 
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/storage"
 	"github.com/timescale/promscale/pkg/pgmodel/cache"
 	"github.com/timescale/promscale/pkg/pgmodel/lreader"
 	"github.com/timescale/promscale/pkg/pgxconn"
+	"github.com/timescale/promscale/pkg/rollup"
 	"github.com/timescale/promscale/pkg/tenancy"
 )
 
 type pgxQuerier struct {
-	tools *queryTools
+	tools  *queryTools
+	schema *rollup.Decider
 }
 
 var _ Querier = (*pgxQuerier)(nil)
@@ -29,7 +33,9 @@ func NewQuerier(
 	labelsReader lreader.LabelsReader,
 	exemplarCache cache.PositionCache,
 	rAuth tenancy.ReadAuthorizer,
-) Querier {
+	scrapeInterval time.Duration,
+	useRollups bool,
+) (Querier, error) {
 	querier := &pgxQuerier{
 		tools: &queryTools{
 			conn:             conn,
@@ -39,15 +45,22 @@ func NewQuerier(
 			rAuth:            rAuth,
 		},
 	}
-	return querier
+	if useRollups {
+		decider, err := rollup.NewDecider(context.Background(), conn, scrapeInterval)
+		if err != nil {
+			return nil, fmt.Errorf("error creating rollups schema decider: %w", err)
+		}
+		querier.schema = decider
+	}
+	return querier, nil
 }
 
 func (q *pgxQuerier) RemoteReadQuerier(ctx context.Context) RemoteReadQuerier {
 	return newQueryRemoteRead(ctx, q)
 }
 
 func (q *pgxQuerier) SamplesQuerier(ctx context.Context) SamplesQuerier {
-	return newQuerySamples(ctx, q)
+	return newQuerySamples(ctx, q, q.schema)
 }
 
 func (q *pgxQuerier) ExemplarsQuerier(ctx context.Context) ExemplarQuerier {

pkg/pgmodel/querier/querier_sql_test.go

@@ -722,7 +722,12 @@ func TestPGXQuerierQuery(t *testing.T) {
 			if err != nil {
 				t.Fatalf("error setting up mock cache: %s", err.Error())
 			}
-			querier := pgxQuerier{&queryTools{conn: mock, metricTableNames: mockMetrics, labelsReader: lreader.NewLabelsReader(mock, clockcache.WithMax(0), tenancy.NewNoopAuthorizer().ReadAuthorizer())}}
+			querier := pgxQuerier{
+				&queryTools{
+					conn: mock, metricTableNames: mockMetrics, labelsReader: lreader.NewLabelsReader(mock, clockcache.WithMax(0), tenancy.NewNoopAuthorizer().ReadAuthorizer()),
+				},
+				nil,
+			}
 
 			result, err := querier.RemoteReadQuerier(context.Background()).Query(c.query)
 

pkg/pgmodel/querier/query_remote_read.go

@@ -28,7 +28,7 @@ func (q *queryRemoteRead) Query(query *prompb.Query) ([]*prompb.TimeSeries, erro
 		return nil, err
 	}
 
-	qrySamples := newQuerySamples(q.ctx, q.pgxQuerier)
+	qrySamples := newQuerySamples(q.ctx, q.pgxQuerier, nil)
 	sampleRows, _, err := qrySamples.fetchSamplesRows(query.StartTimestampMs, query.EndTimestampMs, nil, nil, nil, matchers)
 	if err != nil {
 		return nil, err

pkg/pgmodel/querier/query_sample.go

@@ -9,17 +9,20 @@ import (
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/promql/parser"
 	"github.com/prometheus/prometheus/storage"
+	"github.com/timescale/promscale/pkg/log"
 	"github.com/timescale/promscale/pkg/pgmodel/common/errors"
 	"github.com/timescale/promscale/pkg/pgmodel/common/schema"
+	"github.com/timescale/promscale/pkg/rollup"
 )
 
 type querySamples struct {
 	*pgxQuerier
-	ctx context.Context
+	ctx    context.Context
+	schema *rollup.Decider
 }
 
-func newQuerySamples(ctx context.Context, qr *pgxQuerier) *querySamples {
-	return &querySamples{qr, ctx}
+func newQuerySamples(ctx context.Context, qr *pgxQuerier, schema *rollup.Decider) *querySamples {
+	return &querySamples{qr, ctx, schema}
 }
 
 // Select implements the SamplesQuerier interface. It is the entry point for our
@@ -39,6 +42,24 @@ func (q *querySamples) fetchSamplesRows(mint, maxt int64, hints *storage.SelectH
 		return nil, nil, fmt.Errorf("get evaluation metadata: %w", err)
 	}
 
+	var useRollups bool
+	if q.schema != nil {
+		// Querying via rollups is available.
+		supported := q.schema.SupportsRollup(metadata.metric) // Ensure that rollups for the given metric is supported.
+		if !supported {
+			// Rollups for the given metric wasn't supported. Let's refresh and check again.
+			if err := q.schema.Refresh(); err != nil {
+				log.Error("msg", "error refreshing schema decider", "error", err.Error())
+			}
+			supported = q.schema.SupportsRollup(metadata.metric) // If supported is still false, then rollups really don't exist for 'metadata.metric'.
+		}
+		if supported {
+			schemaName := q.schema.Decide(mint, maxt)
+			useRollups = schemaName != rollup.DefaultSchema
+		}
+	}
+	_ = useRollups // To avoid unused error. This will be used in the following PRs for querying rollups.
+
 	filter := metadata.timeFilter
 	if metadata.isSingleMetric {
 		// Single vector selector case.

pkg/rollup/config.go

@@ -17,6 +17,7 @@ import (
 )
 
 const (
+	DefaultScrapeInterval        = time.Second * 30
 	setDefaultDownsampleStateSQL = "SELECT prom_api.set_automatic_downsample($1)"
 
 	// short and long represent system resolutions.