diff --git a/ext/repair/sqlite3_checker.tcl b/ext/repair/sqlite3_checker.tcl
index ab8d05e600..88c265f93c 100644
--- a/ext/repair/sqlite3_checker.tcl
+++ b/ext/repair/sqlite3_checker.tcl
@@ -42,7 +42,7 @@ proc tclsh {} {
 
 # Do an incremental integrity check of a single index
 #
-proc check_index {idxname batchsize} {
+proc check_index {idxname batchsize bTrace} {
   set i 0
   set more 1
   set nerr 0
@@ -51,18 +51,30 @@ proc check_index {idxname batchsize} {
                     WHERE name=$idxname}]
   puts -nonewline "$idxname: $i of $max rows ($pct%)\r"
   flush stdout
-  while {$more} {
-    set more 0
-    db eval {SELECT errmsg, current_key AS key
+  if {$bTrace} {
+    set sql {SELECT errmsg, current_key AS key,
+                    CASE WHEN rowid=1 THEN scanner_sql END AS traceOut
                FROM incremental_index_check($idxname)
               WHERE after_key=$key
-              LIMIT $batchsize} {
+              LIMIT $batchsize}
+  } else {
+    set sql {SELECT errmsg, current_key AS key, NULL AS traceOut
+               FROM incremental_index_check($idxname)
+              WHERE after_key=$key
+              LIMIT $batchsize}
+  }
+  while {$more} {
+    set more 0
+    db eval $sql {
       set more 1
       if {$errmsg!=""} {
         incr nerr
         puts "$idxname: key($key): $errmsg"
+      } elseif {$traceOut!=""} {
+        puts "$idxname: $traceOut"
       }
       incr i
+      
     }
     set x [format {%.1f} [expr {($i*100.0)/$max}]]
     if {$x!=$pct} {
@@ -97,6 +109,8 @@ Options:
 
    --tclsh           Run the built-in TCL interpreter (for debugging)
 
+   --trace           (Debugging only:) Output trace information on the scan
+
    --version         Show the version number of SQLite
 }
   exit 1
@@ -110,6 +124,7 @@ set zIndex {}
 set zTable {}
 set batchsize 1000
 set bAll 1
+set bTrace 0
 set argc [llength $argv]
 for {set i 0} {$i<$argc} {incr i} {
   set arg [lindex $argv $i]
@@ -133,6 +148,10 @@ for {set i 0} {$i<$argc} {incr i} {
     set bAll 0
     continue
   }
+  if {[regexp {^-+trace$} $arg]} {
+    set bTrace 1
+    continue
+  }
   if {[regexp {^-+batchsize$} $arg]} {
     incr i
     if {$i>=$argc} {
@@ -224,13 +243,13 @@ if {$bSummary} {
   }
 }
 if {$zIndex!=""} {
-  check_index $zIndex $batchsize
+  check_index $zIndex $batchsize $bTrace
 }
 if {$zTable!=""} {
   foreach idx [db eval {SELECT name FROM sqlite_master
                          WHERE type='index' AND rootpage>0
                            AND tbl_name=$zTable}] {
-    check_index $idx $batchsize
+    check_index $idx $batchsize $bTrace
   }
 }
 if {$bAll} {
@@ -238,6 +257,6 @@ if {$bAll} {
                         WHERE type='index' AND rootpage>0
                         ORDER BY nEntry}]
   foreach idx $allidx {
-    check_index $idx $batchsize
+    check_index $idx $batchsize $bTrace
   }
 }
diff --git a/manifest b/manifest
index d1fed8a386..9879a2fe85 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Enhance\sthe\scheckindex.c\svirtual\stable\sso\sthat\sit\swill\soutput\sthe\nindex_name\sand\safter_key\sparameters.\s\sAlso\sadd\sa\snew\sdiagnostic\soutput\ncolumn\snamed\sscanner_sql\swhich\sshows\sthe\sSQL\sstatement\sused\sto\simplement\nthe\scurrent\sindex\sscan.
-D 2017-11-07T16:23:24.445
+C Add\sthe\s--trace\soption\sto\sthe\ssqlite3_checker\sutility\sprogram.
+D 2017-11-07T16:54:20.340
 F Makefile.in b142eb20482922153ebc77b261cdfd0a560ed05a81e9f6d9a2b0e8192922a1d2
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc a55372a22454e742ba7c8f6edf05b83213ec01125166ad7dcee0567e2f7fc81b
@@ -330,7 +330,7 @@ F ext/repair/README.md 92f5e8aae749a4dae14f02eea8e1bb42d4db2b6ce5e83dbcdd6b14469
 F ext/repair/checkfreelist.c 0dbae18c1b552f58d64f8969e4fb1e7f11930c60a8c2a9a8d50b7f15bdfd54bd
 F ext/repair/checkindex.c 50264729469ae44abe9ce6c78944ec577e50faf26e362f3036142425807a8b67
 F ext/repair/sqlite3_checker.c.in 4a5a3af3f450fe503e5a2985e98516dc2a6b9ad247449e284c1cf140fc91720f
-F ext/repair/sqlite3_checker.tcl 4820d7f58428d47336874b5a148a95b4dad38fe5da72286c01a861590b8f8337
+F ext/repair/sqlite3_checker.tcl cc69e7fbc163f94da4a6400609be001543442d9f8f57a797d1eeb7b897585730
 F ext/repair/test/README.md 34b2f542cf5be7bffe479242b33ee3492cea30711e447cc4a1a86cb5915f419e
 F ext/repair/test/checkfreelist01.test 3e8aa6aeb4007680c94a8d07b41c339aa635cc78249442da72ff3f8297398a69
 F ext/repair/test/checkindex01.test c4c9e62b1068ddb2d8b5c75580c3036713fc27ec105bbc579114da4ab29d53f4
@@ -1673,7 +1673,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 66d98310b91c69fd01c6a9a958ef1eabda14ec6cd0e4b6612f877f2dfe486c54
-R 9707d9dec21c954b720b6c37687c0a3c
+P 32e2520ce91351acceda845d81c9567f7a634257dc2b5b90fe6fb6583d8c0f87
+R d811e2909e0aaa74e9aeec168920f2dd
 U drh
-Z a2de00e6bfce7f49b15935d74b6b30ce
+Z c6a691c1b309b32f8cd47b4317d437a7
diff --git a/manifest.uuid b/manifest.uuid
index 938db32b6b..c71454aad5 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-32e2520ce91351acceda845d81c9567f7a634257dc2b5b90fe6fb6583d8c0f87
\ No newline at end of file
+dc217b7cfe680044d8742e317701abd0269162da8f5cb097361ae7f47fd9ba2d
\ No newline at end of file