Coordinator docs

README.md

@@ -255,6 +255,12 @@ psql -h localhost -p 55432 -U postgres
 ./cluster down all
 ```
 
+## Quick Start: Production Deployment
+
+In a production deployment, each Springtail host runs a `coordinator` process that supervises the daemons for one service tier (`ingestion`, `fdw`, or `proxy`), installs binaries from S3, monitors component liveness via Redis, and reacts to lifecycle state changes (startup, reload, drain, shutdown) driven by the controller.
+
+For details on starting Springtail, adding replica (FDW) nodes, removing replica nodes, and stopping Springtail, see [`python/coordinator/README.md`](python/coordinator/README.md).
+
 ## License
 
 This project is licensed under the Elastic License 2.0 (ELv2).

include/sys_tbl_mgr/table.hh

@@ -184,6 +184,10 @@ namespace indexer_helpers {
                     const Tracker& tb = b;
 
                     if (ta == tb) {
+                        // Vacant table: both trackers carry null btrees; nothing more to compare.
+                        if (a._btree == nullptr) {
+                            return true;
+                        }
                         return (a._btree_i == a._btree->end() || a._page_i == b._page_i);
                     }
                     return false;
@@ -496,8 +500,8 @@ namespace indexer_helpers {
          */
         Iterator end(uint64_t index_id = constant::INDEX_PRIMARY, bool index_only = false)
         {
-            // check for vacant table
-            if (index_id == constant::INDEX_PRIMARY && _primary_index == nullptr) {
+            // check for vacant table - return a vacant iterator regardless of index type
+            if (_primary_index == nullptr) {
                 return Iterator(this);
             }
             return Iterator(this, index_id, index_only);
@@ -512,6 +516,11 @@ namespace indexer_helpers {
             if (idx == 0) {
                 return _primary_index;
             }
+            // Vacant table: _secondary_indexes is empty; return null instead of throwing,
+            // matching the primary-index behavior on a vacant table.
+            if (_primary_index == nullptr) {
+                return nullptr;
+            }
             return _secondary_indexes.at(idx).first;
         }