catalog: add histogram metric for allocate_id

Author: aljoscha

src/catalog/src/durable.rs

@@ -12,7 +12,7 @@
 use std::fmt::Debug;
 use std::num::NonZeroI64;
 use std::sync::Arc;
-use std::time::Duration;
+use std::time::{Duration, Instant};
 
 use async_trait::async_trait;
 use itertools::Itertools;
@@ -211,6 +211,9 @@ pub trait ReadOnlyDurableCatalogState: Debug + Send + Sync {
     /// NB: We may remove this in later iterations of Pv2.
     fn epoch(&self) -> Epoch;
 
+    /// Returns the metrics for this catalog state.
+    fn metrics(&self) -> &Metrics;
+
     /// Politely releases all external resources that can only be released in an async context.
     async fn expire(self: Box<Self>);
 
@@ -323,12 +326,16 @@ pub trait DurableCatalogState: ReadOnlyDurableCatalogState {
         amount: u64,
         commit_ts: Timestamp,
     ) -> Result<Vec<u64>, CatalogError> {
+        let start = Instant::now();
         if amount == 0 {
             return Ok(Vec::new());
         }
         let mut txn = self.transaction().await?;
         let ids = txn.get_and_increment_id_by(id_type.to_string(), amount)?;
         txn.commit_internal(commit_ts).await?;
+        self.metrics()
+            .allocate_id_seconds
+            .observe(start.elapsed().as_secs_f64());
         Ok(ids)
     }
 

src/catalog/src/durable/metrics.rs

@@ -11,7 +11,8 @@
 
 use mz_ore::metric;
 use mz_ore::metrics::{IntCounter, MetricsRegistry};
-use prometheus::{Counter, IntGaugeVec};
+use mz_ore::stats::histogram_seconds_buckets;
+use prometheus::{Counter, Histogram, IntGaugeVec};
 
 #[derive(Debug, Clone)]
 pub struct Metrics {
@@ -23,6 +24,7 @@ pub struct Metrics {
     pub syncs: IntCounter,
     pub sync_latency_seconds: Counter,
     pub collection_entries: IntGaugeVec,
+    pub allocate_id_seconds: Histogram,
 }
 
 impl Metrics {
@@ -62,6 +64,11 @@ impl Metrics {
                 help: "Total number of entries, after consolidation, per catalog collection.",
                 var_labels: ["collection"],
             )),
+            allocate_id_seconds: registry.register(metric!(
+                name: "mz_catalog_allocate_id_seconds",
+                help: "The time it takes to allocate IDs in the durable catalog.",
+                buckets: histogram_seconds_buckets(0.001, 32.0),
+            )),
         }
     }
 }

src/catalog/src/durable/persist.rs

@@ -1599,6 +1599,10 @@ impl ReadOnlyDurableCatalogState for PersistCatalogState {
             .epoch
     }
 
+    fn metrics(&self) -> &Metrics {
+        &self.metrics
+    }
+
     #[mz_ore::instrument(level = "debug")]
     async fn expire(self: Box<Self>) {
         self.expire().await