Switch jemalloc to mimalloc; refactor classifier & cleanup

Replace the optional tikv-jemallocator with mimalloc and add rmp-serde as a dependency. Update imports and usages to the new kalamdb_sql::classifier module (previously statement_classifier) across executor, handlers, and tests. Remove multiple legacy compatibility shims and fallbacks: deprecated auth rbac/roles shims, legacy ID storage-key parsing paths, legacy system schema constants and system_table partitions, and older conversion aliases (encode_pk_value). Simplify filestore re-exports, remove legacy environment-variable fallbacks from server config overrides, and adjust raft codec serialization by splitting envelope types for encode/decode. Miscellaneous comment/test updates and cleanup to align the codebase with the new allocator and serialization choices.

Author: jamals86

Cargo.lock

@@ -133,6 +133,7 @@ criterion = { version = "0.8.2", features = ["html_reports"] }
 
 # Raft consensus
 openraft = { version = "0.9.21", features = ["serde"] }
+rmp-serde = "1.3"
 
 # gRPC for Raft network layer
 tonic = { version = "0.14.5" }

Cargo.toml

@@ -10,7 +10,7 @@ build = "build.rs"
 
 [dependencies]
 # Memory optimization
-tikv-jemallocator = { version = "0.6.1", optional = true }
+mimalloc = { version = "0.1", default-features = false, optional = true }
 
 # Core library
 kalamdb-core = { path = "crates/kalamdb-core" }
@@ -81,8 +81,8 @@ num_cpus = { workspace = true }
 libc = { workspace = true }
 
 [features]
-default = ["embedded-ui", "jemalloc"]
-jemalloc = ["tikv-jemallocator"]
+default = ["embedded-ui", "mimalloc"]
+mimalloc = ["dep:mimalloc"]
 embedded-ui = ["kalamdb-api/embedded-ui"]
 otel = ["dep:tracing-opentelemetry", "dep:opentelemetry", "dep:opentelemetry_sdk", "dep:opentelemetry-otlp"]
 # End-to-end tests that require a full test server instance

backend/Cargo.toml

@@ -28,7 +28,7 @@ pub mod sql;
 pub mod topics;
 pub mod ws;
 
-// Re-export for backwards compatibility and convenient access
+// Re-export for convenient access
 pub use auth::{
     login_handler, logout_handler, me_handler, refresh_handler, server_setup_handler,
     setup_status_handler,

backend/crates/kalamdb-api/src/handlers/mod.rs

@@ -239,8 +239,8 @@ fn classify_sql(
     default_namespace: &NamespaceId,
     exec_ctx: &ExecutionContext,
     start_time: Instant,
-) -> Result<kalamdb_sql::statement_classifier::SqlStatement, HttpResponse> {
-    kalamdb_sql::statement_classifier::SqlStatement::classify_and_parse(
+) -> Result<kalamdb_sql::classifier::SqlStatement, HttpResponse> {
+    kalamdb_sql::classifier::SqlStatement::classify_and_parse(
         sql,
         default_namespace,
         exec_ctx.user_role(),

backend/crates/kalamdb-api/src/handlers/sql/execute.rs

@@ -181,15 +181,15 @@ pub async fn forward_sql_if_follower(
     let has_write = statements.iter().any(|sql| {
         let classify_sql =
             kalamdb_sql::execute_as::extract_inner_sql(sql).unwrap_or_else(|| sql.to_string());
-        let stmt = kalamdb_sql::statement_classifier::SqlStatement::classify_and_parse(
+        let stmt = kalamdb_sql::classifier::SqlStatement::classify_and_parse(
             &classify_sql,
             default_namespace,
             Role::System,
         )
         .unwrap_or_else(|_| {
-            kalamdb_sql::statement_classifier::SqlStatement::new(
+            kalamdb_sql::classifier::SqlStatement::new(
                 classify_sql,
-                kalamdb_sql::statement_classifier::SqlStatementKind::Unknown,
+                kalamdb_sql::classifier::SqlStatementKind::Unknown,
             )
         });
         stmt.is_write_operation()

backend/crates/kalamdb-api/src/handlers/sql/forward.rs

@@ -1,3 +1 @@
-pub mod rbac;
-pub mod roles;
 pub use kalamdb_session::permissions;

backend/crates/kalamdb-auth/src/authorization/mod.rs

@@ -114,13 +114,3 @@ pub const RESERVED_NAMESPACE_NAMES: &[&str] = &[
     "pg_catalog",
     "datafusion",
 ];
-
-/// Legacy system schema version constants.
-///
-/// System schema lifecycle now reconciles through `system.schemas` at startup
-/// (`SchemaRegistry::initialize_tables()`), so this key/version pair is kept
-/// only for backward compatibility during transition.
-pub const SYSTEM_SCHEMA_VERSION: u32 = 1;
-
-/// Legacy RocksDB key for system schema version in default column family.
-pub const SYSTEM_SCHEMA_VERSION_KEY: &str = "system:schema_version";