Add a comment to explain why both sides of an AND must be non-null-row in order

for the overall expression to be non-null-row.  No code changes.

FossilOrigin-Name: 8396032ce14a75f408f0a75bcb36a6504d5188f20886e275746a2c336a74296f

diff --git a/manifest b/manifest
index 3e7143ff50f2cd7813a45727a322da985ffe3dcc..f6d261e0f5d1c7afd7c856c2134b36e49569ab04 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Improved\sdetection\sof\swhen\sthe\sLEFT\sJOIN\sstrength\sreduction\soptimization\ncan\sbe\sapplied.
-D 2023-05-31T18:35:12.759
+C Add\sa\scomment\sto\sexplain\swhy\sboth\ssides\sof\san\sAND\smust\sbe\snon-null-row\sin\sorder\nfor\sthe\soverall\sexpression\sto\sbe\snon-null-row.\s\sNo\scode\schanges.
+D 2023-05-31T18:52:46.557
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -587,7 +587,7 @@ F src/date.c cb71f73d5df5303ec6630971b9c8b8c7df466fa3233dbdc643d613806e53e554
 F src/dbpage.c f3eea5f7ec47e09ee7da40f42b25092ecbe961fc59566b8e5f705f34335b2387
 F src/dbstat.c ec92074baa61d883de58c945162d9e666c13cd7cf3a23bc38b4d1c4d0b2c2bef
 F src/delete.c 05e27e3a55dcfeadf2f7ca95a5c5e0928f182c04640ec1954ffa42f3d5c19341
-F src/expr.c 0081058153a329c21204efd87c6f25bcbc2d70d2d9fd4441c7824778cd056ef3
+F src/expr.c 5671567f095756be0b1f84347965bbd0ce8e4d435255b5a3b6ada694a560ee1b
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c 03c134cc8bffe54835f742ddea0b72ebfc8f6b32773d175c71b8afeea6cb5c83
 F src/func.c 03e6b501f3056d0ba398bda17df938b2b566aa0b3ca7e1942a3cd1925d04ec36
@@ -2072,8 +2072,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P fba97230e38276f2a02fc24353c3d911dfa24f3a4f75f691de9461d4daf3ae54
-R 720aef041ed3aa114fee5b5cb6f34a65
+P f544a8e47cdd5ad7233887a558489983f4f305a39391ff463c43e2e4157da087
+R cfe6e243041fd222123bb8065a03b511
 U drh
-Z d35ccb01f44f9df429a5fed4d723f477
+Z abd461353f82d9e52ac72c2c080f514b
 # Remove this line to create a well-formed Fossil manifest.

diff --git a/manifest.uuid b/manifest.uuid
index 04b87f49a7d2124dfc996971568f22fe2928ec3f..44346c68217d0e40d65cff168a22ec3a203ad750 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-f544a8e47cdd5ad7233887a558489983f4f305a39391ff463c43e2e4157da087
\ No newline at end of file
+8396032ce14a75f408f0a75bcb36a6504d5188f20886e275746a2c336a74296f
\ No newline at end of file

diff --git a/src/expr.c b/src/expr.c
index 7e1483a90ce55919b5b5d7f625c03596aafdbf3a..c7abd161682aa844dd8b4a93bb7831ba379da082 100644 (file)
--- a/src/expr.c
+++ b/src/expr.c
@@ -6030,6 +6030,13 @@ static int impliesNotNullRow(Walker *pWalker, Expr *pExpr){
 
     case TK_OR:
     case TK_AND:
+      /* Both sides of an AND or OR must separately imply non-NULL row.
+      ** Consider these cases:
+      **    1.  NOT (x AND y)
+      **    2.  x OR y
+      ** If only one of x or y is non-null-row, then the overall expression
+      ** can be true if the other arm is false (case 1) or true (case 2).
+      */
       testcase( pExpr->op==TK_OR );
       testcase( pExpr->op==TK_AND );
       if( pWalker->eCode==0 ){