Feike/malloc performance improvements

.cargo/config.toml

@@ -0,0 +1 @@
+config

Changelog.md

@@ -16,6 +16,18 @@ This changelog should be updated as part of a PR if the work is worth noting (mo
 
 **Full Changelog**: [TODO]
 
+## [1.19.0](https://github.com/timescale/timescaledb-toolkit/releases/tag/1.19.0) (2024-11-14)
+
+#### New experimental features
+
+#### Bug fixes
+
+#### Other notable changes
+
+#### Shout-outs
+
+**Full Changelog**: [TODO]
+
 ## [1.18.0](https://github.com/timescale/timescaledb-toolkit/releases/tag/1.18.0) (2023-11-28)
 
 #### New experimental features

crates/udd-sketch/src/compactor.rs

@@ -0,0 +1,45 @@
+use crate::swap::SwapBucket;
+use crate::SketchHashKey::Invalid;
+use crate::{SketchHashEntry, SketchHashKey, SketchHashMap};
+
+#[inline]
+pub fn compact_from_iter(
+    swap_iter: &mut impl Iterator<Item = SwapBucket>,
+    map: &mut SketchHashMap,
+) {
+    let Some(mut current) = swap_iter.next() else {
+        return;
+    };
+
+    for next in swap_iter {
+        if next.key == Invalid {
+            break;
+        }
+
+        // This combines those buckets that compact into the same one
+        // For example, Positive(9) and Positive(8) both
+        // compact into Positive(4)
+        if current.key == next.key {
+            current.count += next.count;
+        } else {
+            map.map.insert(
+                current.key,
+                SketchHashEntry {
+                    count: current.count,
+                    next: next.key,
+                },
+            );
+            current = next;
+        }
+    }
+
+    // And the final one ...
+    map.map.insert(
+        current.key,
+        SketchHashEntry {
+            count: current.count,
+            next: Invalid,
+        },
+    );
+    map.head = map.head.compact_key();
+}