diff --git a/manifest b/manifest
index badcfcb33e..7ab0dcc587 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Ensure\sfts3/4\sprefix\sindexes\sare\sflushed\sto\sdisk\sbefore\san\s'optimize'\scommand.\sFix\sfor\s[745f1abc].
-D 2019-10-11T15:33:13.752
+C Improvements\sto\sthe\sLEFT\sJOIN\sstrength\sreduction\soptimization.
+D 2019-10-11T16:01:21.642
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -477,7 +477,7 @@ F src/date.c e1d8ac7102f3f283e63e13867acb0efa33861cf34f0faf4cdbaf9fa7a1eb7041
 F src/dbpage.c 135eb3b5e74f9ef74bde5cec2571192c90c86984fa534c88bf4a055076fa19b7
 F src/dbstat.c c12833de69cb655751487d2c5a59607e36be1c58ba1f4bd536609909ad47b319
 F src/delete.c d08c9e01a2664afd12edcfa3a9c6578517e8ff8735f35509582693adbe0edeaf
-F src/expr.c 88de5e67b378731da9a45c592122c754693c2a095db61dcd1a0cc64bb72b6145
+F src/expr.c 8e82108846bb8ad0651feb1672eb8aae82158b6240f5677bc72d6cdf80e9d7a8
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c 6271fda51794b569d736eba4097d28f13080cd0c9eb66d5fcecb4b77336fae50
 F src/func.c ed33e38cd642058182a31a3f518f2e34f4bbe53aa483335705c153c4d3e50b12
@@ -1846,7 +1846,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 5863546df99abd1ad4ebcaba18dec647be4368e2c13ce0b28e48c8608d3e87ef
-R 40ae78baf0fb340e9bc66e248358e43e
-U dan
-Z e8d62df0ae7b8d9d3710fd8698abaecb
+P 4ed905b18847d4dbf5a2570052abced338065f824137b90300f62d77b3159d80
+R b207e5537fa5845b32cb8d65da5d4e9f
+U drh
+Z 75f587b0cae941ddcaa1476b9bca25c8
diff --git a/manifest.uuid b/manifest.uuid
index d63c60ec06..fad3987b87 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-4ed905b18847d4dbf5a2570052abced338065f824137b90300f62d77b3159d80
\ No newline at end of file
+548082dfab5d9484279ccc11cd2833ac131b54b7481372b576d7c28bbb3294ea
\ No newline at end of file
diff --git a/src/expr.c b/src/expr.c
index b1f405cdc9..e28a7b044e 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -5231,8 +5231,12 @@ static int impliesNotNullRow(Walker *pWalker, Expr *pExpr){
 int sqlite3ExprImpliesNonNullRow(Expr *p, int iTab){
   Walker w;
   p = sqlite3ExprSkipCollateAndLikely(p);
-  if( p && p->op==TK_NOTNULL ){
+  if( p==0 ) return 0;
+  if( p->op==TK_NOTNULL ){
     p = p->pLeft;
+  }else if( p->op==TK_AND ){
+    if( sqlite3ExprImpliesNonNullRow(p->pLeft, iTab) ) return 1;
+    p = p->pRight;
   }
   w.xExprCallback = impliesNotNullRow;
   w.xSelectCallback = 0;