chore(cubestore): Upgrade DF: Add sql data frame serialization time metric

Author: srh

rust/cubestore/cubestore/src/app_metrics.rs

@@ -53,6 +53,9 @@ pub static DATA_QUERY_CREATE_ROUTER_PHYSICAL_PLAN_US: Histogram =
 pub static DATA_QUERY_CREATE_WORKER_PHYSICAL_PLAN_US: Histogram =
     metrics::histogram("cs.sql.query.data.planning.worker_plan.us");
 
+pub static SQL_QUERY_DATA_FRAME_SERIALIZATION_TIME_US: Histogram =
+    metrics::histogram("cs.sql.query.data_frame_serialization.us");
+
 /// Incoming SQL queries that only read metadata or do trivial computations.
 pub static META_QUERIES: Counter = metrics::counter("cs.sql.query.meta");
 pub static META_QUERY_TIME_MS: Histogram = metrics::histogram("cs.sql.query.meta.ms");

rust/cubestore/cubestore/src/mysql/mod.rs

@@ -2,7 +2,7 @@ use crate::config::processing_loop::ProcessingLoop;
 use crate::sql::{InlineTables, SqlQueryContext, SqlService};
 use crate::table::TableValue;
 use crate::util::time_span::warn_long;
-use crate::{metastore, CubeError};
+use crate::{app_metrics, metastore, CubeError};
 use async_trait::async_trait;
 use datafusion::cube_ext;
 use hex::ToHex;
@@ -78,6 +78,9 @@ impl<W: io::Write + Send> AsyncMysqlShim<W> for Backend {
         }
         let _s = warn_long("sending query results", Duration::from_millis(100));
         let data_frame = res.unwrap();
+
+        let data_frame_serialization_start_time = SystemTime::now();
+
         let columns = data_frame
             .get_columns()
             .iter()
@@ -133,7 +136,15 @@ impl<W: io::Write + Send> AsyncMysqlShim<W> for Backend {
             rw.end_row()?;
         }
         rw.finish()?;
-        if start.elapsed().unwrap().as_millis() > 200 && query.to_lowercase().starts_with("select")
+
+        let end_time = SystemTime::now();
+        app_metrics::SQL_QUERY_DATA_FRAME_SERIALIZATION_TIME_US.report(
+            end_time
+                .duration_since(data_frame_serialization_start_time)?
+                .as_micros() as i64,
+        );
+        if end_time.duration_since(start).unwrap().as_millis() > 200
+            && query.to_lowercase().starts_with("select")
         {
             warn!(
                 "Slow Query SQL ({:?}):\n{}",