chore(query): Optimize hot path allocations in query formatting and metadata operations

src/meta/api/src/kv_pb_api/mod.rs

@@ -212,14 +212,15 @@ pub trait KVPbApi: KVApi {
         Self::Error: From<PbApiReadError<Self::Error>>,
     {
         let it = keys.into_iter();
-        let key_chunks = it
+        let key_chunks: Vec<Vec<K>> = it
             .chunks(Self::CHUNK_SIZE)
             .into_iter()
             .map(|x| x.collect::<Vec<_>>())
             .collect::<Vec<_>>();
+        let total_keys: usize = key_chunks.iter().map(|c| c.len()).sum();
 
         async move {
-            let mut res = vec![];
+            let mut res = Vec::with_capacity(total_keys);
             for chunk in key_chunks {
                 let strm = self.get_pb_values(chunk).await?;
 
@@ -278,14 +279,15 @@ pub trait KVPbApi: KVApi {
         Self::Error: From<PbApiReadError<Self::Error>>,
     {
         let it = keys.into_iter();
-        let key_chunks = it
+        let key_chunks: Vec<Vec<K>> = it
             .chunks(Self::CHUNK_SIZE)
             .into_iter()
             .map(|x| x.collect::<Vec<_>>())
             .collect::<Vec<_>>();
+        let total_keys: usize = key_chunks.iter().map(|c| c.len()).sum();
 
         async move {
-            let mut res = vec![];
+            let mut res = Vec::with_capacity(total_keys);
             for chunk in key_chunks {
                 let strm = self.get_pb_stream(chunk).await?;
 

src/meta/kvapi/src/kvapi/key_builder.rs

@@ -14,6 +14,8 @@
 
 //! A helper for building a string key from a structured key
 
+use std::io::Write;
+
 use crate::kvapi::helper::escape;
 use crate::kvapi::helper::escape_specified;
 
@@ -46,8 +48,15 @@ impl KeyBuilder {
         self.push_raw(&escape(s))
     }
 
-    pub fn push_u64(self, n: u64) -> Self {
-        self.push_raw(&format!("{}", n))
+    pub fn push_u64(mut self, n: u64) -> Self {
+        if !self.buf.is_empty() {
+            // `/`
+            self.buf.push(0x2f);
+        }
+
+        // Write directly to buffer instead of allocating a string
+        write!(self.buf, "{}", n).unwrap();
+        self
     }
 
     pub fn done(self) -> String {

src/query/ast/src/parser/error.rs

@@ -255,7 +255,7 @@ pub fn display_parser_error(error: Error, source: &str) -> String {
             format!("unexpected `{span_text}`")
         };
         if let Some(suggestion) = has_suggestion {
-            msg += &format!(". {}", suggestion);
+            write!(msg, ". {}", suggestion).unwrap();
             labels = vec![(inner.span, msg)];
 
             // Return early to skip context labels when we have intelligent suggestions
@@ -270,15 +270,15 @@ pub fn display_parser_error(error: Error, source: &str) -> String {
                     write!(msg, ", or {} more ...", more).unwrap();
                     break;
                 } else if i == 0 {
-                    msg += ", expecting ";
+                    msg.push_str(", expecting ");
                 } else if iter.peek().is_none() && i == 1 {
-                    msg += " or ";
+                    msg.push_str(" or ");
                 } else if iter.peek().is_none() {
-                    msg += ", or ";
+                    msg.push_str(", or ");
                 } else {
-                    msg += ", ";
+                    msg.push_str(", ");
                 }
-                msg += error;
+                msg.push_str(error);
             }
 
             labels = vec![(inner.span, msg)];

src/query/sql/src/executor/format.rs

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 use std::collections::HashMap;
+use std::fmt::Write;
 
 use databend_common_ast::ast::FormatTreeNode;
 use databend_common_base::base::format_byte_size;
@@ -1788,59 +1789,69 @@ fn part_stats_info_to_format_tree(info: &PartStatistics) -> Vec<FormatTreeNode<S
 
     // range pruning status.
     if info.pruning_stats.blocks_range_pruning_before > 0 {
-        blocks_pruning_description += &format!(
+        write!(
+            blocks_pruning_description,
             "range pruning: {} to {}",
             info.pruning_stats.blocks_range_pruning_before,
             info.pruning_stats.blocks_range_pruning_after
-        );
+        )
+        .unwrap();
     }
 
     // bloom pruning status.
     if info.pruning_stats.blocks_bloom_pruning_before > 0 {
         if !blocks_pruning_description.is_empty() {
-            blocks_pruning_description += ", ";
+            blocks_pruning_description.push_str(", ");
         }
-        blocks_pruning_description += &format!(
+        write!(
+            blocks_pruning_description,
             "bloom pruning: {} to {}",
             info.pruning_stats.blocks_bloom_pruning_before,
             info.pruning_stats.blocks_bloom_pruning_after
-        );
+        )
+        .unwrap();
     }
 
     // inverted index pruning status.
     if info.pruning_stats.blocks_inverted_index_pruning_before > 0 {
         if !blocks_pruning_description.is_empty() {
-            blocks_pruning_description += ", ";
+            blocks_pruning_description.push_str(", ");
         }
-        blocks_pruning_description += &format!(
+        write!(
+            blocks_pruning_description,
             "inverted pruning: {} to {}",
             info.pruning_stats.blocks_inverted_index_pruning_before,
             info.pruning_stats.blocks_inverted_index_pruning_after
-        );
+        )
+        .unwrap();
     }
 
     // topn pruning status.
     if info.pruning_stats.blocks_topn_pruning_before > 0 {
         if !blocks_pruning_description.is_empty() {
-            blocks_pruning_description += ", ";
+            blocks_pruning_description.push_str(", ");
         }
-        blocks_pruning_description += &format!(
+        write!(
+            blocks_pruning_description,
             "topn pruning: {} to {}",
             info.pruning_stats.blocks_topn_pruning_before,
             info.pruning_stats.blocks_topn_pruning_after
-        );
+        )
+        .unwrap();
     }
 
     // vector index pruning status.
     if info.pruning_stats.blocks_vector_index_pruning_before > 0 {
         if !blocks_pruning_description.is_empty() {
-            blocks_pruning_description += ", ";
+            blocks_pruning_description.push_str(", ");
         }
-        blocks_pruning_description += &format!(
+        write!(
+            blocks_pruning_description,
             "vector pruning: {} to {}",
             info.pruning_stats.blocks_vector_index_pruning_before,
             info.pruning_stats.blocks_vector_index_pruning_after
-        );
+        )
+        .unwrap();
     }
 
     // Combine segment pruning and blocks pruning descriptions if any
@@ -1850,18 +1861,20 @@ fn part_stats_info_to_format_tree(info: &PartStatistics) -> Vec<FormatTreeNode<S
         let mut pruning_description = String::new();
 
         if info.pruning_stats.segments_range_pruning_before > 0 {
-            pruning_description += &format!(
+            write!(
+                pruning_description,
                 "segments: <range pruning: {} to {}>",
                 info.pruning_stats.segments_range_pruning_before,
                 info.pruning_stats.segments_range_pruning_after
-            );
+            )
+            .unwrap();
         }
 
         if !blocks_pruning_description.is_empty() {
             if !pruning_description.is_empty() {
-                pruning_description += ", ";
+                pruning_description.push_str(", ");
             }
-            pruning_description += &format!("blocks: <{}>", blocks_pruning_description);
+            write!(pruning_description, "blocks: <{}>", blocks_pruning_description).unwrap();
         }
 
         items.push(FormatTreeNode::new(format!(