From 7dfb697b8e62508236f7465503dd2b0e16188a1f Mon Sep 17 00:00:00 2001
From: Ian O'Dwyer <49337701+iodwyer@users.noreply.github.com>
Date: Fri, 18 Sep 2026 10:23:34 +1000
Subject: [PATCH] Refactor savetables function to exit early for 0 rows

---
 code/wdb/writedown.q | 46 ++++++++++++++++++++++++++------------------
 1 file changed, 27 insertions(+), 19 deletions(-)

diff --git a/code/wdb/writedown.q b/code/wdb/writedown.q
index d7ab15589..8dbe85b9c 100644
--- a/code/wdb/writedown.q
+++ b/code/wdb/writedown.q
@@ -26,26 +26,34 @@ tabsizes:([tablename:`symbol$()] rowcount:`long$(); bytes:`long$());       /- ke
 
 savetables:{[dir;pt;forcesave;tabname]
         /- check row count
-        /- forcesave will write flush the data to disk irrespective of counts
-        if[forcesave or maxrows[tabname] < arows: count value tabname;
+        arows:count value tabname;
         .lg.o[`rowcheck;"the ",(string tabname)," table consists of ", (string arows), " rows"];
-        /- upsert data to partition
-        .lg.o[`save;"saving ",(string tabname)," data to partition ", string pt];
-        .[
-                upsert;
-                (` sv .Q.par[dir;pt;tabname],`;.Q.en[hdbsettings[`hdbdir];r:0!.save.manipulate[tabname;`. tabname]]);
-                {[e] .lg.e[`savetables;"Failed to save table to disk : ",e];'e}
-        ];
-        /- make addition to tabsizes
-        .lg.o[`track;"appending table details to tabsizes"];
-        .wdb.tabsizes+:([tablename:enlist tabname]rowcount:enlist arows;bytes:enlist -22!r);
-        /- empty the table
-        .lg.o[`delete;"deleting ",(string tabname)," data from in-memory table"];
-        @[`.;tabname;0#];
-        /- run a garbage collection (if enabled)
-        if[gc;.gc.run[]];
-        :1b;
-          ]; 0b};
+        
+        /- exit early if 0 row count, return 0b for no changes to table
+        if[0 = arows;:0b];
+        
+        /- forcesave will write flush the data to disk irrespective of counts
+        if[forcesave or maxrows[tabname] < arows;
+                /- upsert data to partition
+                .lg.o[`save;"saving ",(string tabname)," data to partition ", string pt];
+                .[
+                        upsert;
+                        (` sv .Q.par[dir;pt;tabname],`;.Q.en[hdbsettings[`hdbdir];r:0!.save.manipulate[tabname;`. tabname]]);
+                        {[e] .lg.e[`savetables;"Failed to save table to disk : ",e];'e}
+                ];
+                /- make addition to tabsizes
+                .lg.o[`track;"appending table details to tabsizes"];
+                .wdb.tabsizes+:([tablename:enlist tabname]rowcount:enlist arows;bytes:enlist -22!r);
+                /- empty the table
+                .lg.o[`delete;"deleting ",(string tabname)," data from in-memory table"];
+                @[`.;tabname;0#];
+                /- run a garbage collection (if enabled)
+                if[gc;.gc.run[]];
+                :1b;
+        ]; 
+        :0b
+        };
+
 
 \d .
 /-endofperiod function