b29509b0535fc8c0151dc3dc47d7be9ec2833294
hiram
  Mon Mar 30 14:28:59 2026 -0700
gcOnFly now with a density switch to go to backup bigWig file to avoid big computation refs #35958

diff --git src/hg/makeDb/trackDb/trackDb.ra src/hg/makeDb/trackDb/trackDb.ra
index 49379be8433..9b0ebe0ff99 100644
--- src/hg/makeDb/trackDb/trackDb.ra
+++ src/hg/makeDb/trackDb/trackDb.ra
@@ -1646,31 +1646,32 @@
 altColor 128,128,128
 viewLimits 30:70
 type bigWig 0 100
 html gc5Base
 
 # gcOnFly is a synthetic track, computed at run time
 # this trackDb entry will allow it to operate properly with
 # correct visibility when a saved session is restored
 track gcOnFly
 release alpha
 shortLabel GC TDB Percent
 longLabel GC TDB Percent in 5-Base Windows
 group map
 visibility hide
 type bigWig 0 100
-bigDataUrl /dev/null
+bigDataUrl /gbdb/$D/bbi/$D.gcOnFly.bw
+gcOnFlyMaxDensity 50000
 syntheticTrack on
 calcWinSize 5
 autoScale Off
 viewLimits 30:70
 maxHeightPixels 128:36:16
 graphTypeDefault Bar
 gridDefault OFF
 windowingFunction Mean
 color 0,0,0
 altColor 128,128,128
 
 track ensemblGeneScaffold
 shortLabel Ensembl Assembly
 longLabel Ensembl Gene Scaffold Assembly
 group map