Comment enhancements. Add an ALWAYS macro in fkey.c to indicate a branch

that is always taken.

FossilOrigin-Name: d5b714cffffe588dd4dd10e0b82df8d99657be88

manifest

@@ -1,5 +1,8 @@
-C Ensure\sforeign\skey\srelated\sprocessing\stakes\splace\swhen\srows\sare\sdeleted\sfrom\sthe\sdatabase\sby\sREPLACE\sconflict\shandling.
-D 2009-09-24T11:31:22
+-----BEGIN PGP SIGNED MESSAGE-----
+Hash: SHA1
+
+C Comment\senhancements.\s\sAdd\san\sALWAYS\smacro\sin\sfkey.c\sto\sindicate\sa\sbranch\nthat\sis\salways\staken.
+D 2009-09-24T13:48:11
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 4ca3f1dd6efa2075bcb27f4dc43eef749877740d
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -116,7 +119,7 @@ F src/date.c 657ff12ca0f1195b531561afacbb38b772d16638
 F src/delete.c 2a3d6fc0861b2f8dbd9feb7847b390267b281c60
 F src/expr.c c7f3f718bd5c392344ec8694a41c1824f30cf375
 F src/fault.c dc88c821842157460750d2d61a8a8b4197d047ff
-F src/fkey.c a1c293cca23700bae7924396055c8d6a14f711c2
+F src/fkey.c 3a5f73fd9ace2dac8d2065a0cad2a92ee05ba60a
 F src/func.c e536218d193b8d326aab91120bc4c6f28aa2b606
 F src/global.c 271952d199a8cc59d4ce840b3bbbfd2f30c8ba32
 F src/hash.c ebcaa921ffd9d86f7ea5ae16a0a29d1c871130a7
@@ -164,7 +167,7 @@ F src/select.c 1d0a13137532321b4364f964e46f057d271691e3
 F src/shell.c d6e64471aafb81f355262533393169a70529847a
 F src/sqlite.h.in 5af8181f815831a8672c3834c60e6b4418448bcc
 F src/sqlite3ext.h 1db7d63ab5de4b3e6b83dd03d1a4e64fef6d2a17
-F src/sqliteInt.h f1ab717f3ea62629faca73bba9a229a96e6a6a5b
+F src/sqliteInt.h 7dcffff0e91ff07e3f7752c4d8e87f9582443a20
 F src/sqliteLimit.h 504a3161886d2938cbd163054ad620b8356df758
 F src/status.c 237b193efae0cf6ac3f0817a208de6c6c6ef6d76
 F src/table.c cc86ad3d6ad54df7c63a3e807b5783c90411a08d
@@ -755,7 +758,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
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manifest.uuid

@@ -1 +1 @@
-3f40c142c8526c1572020bd4d945c03a72019135
+d5b714cffffe588dd4dd10e0b82df8d99657be88

src/fkey.c

@@ -846,11 +846,13 @@ static Trigger *fkActionTrigger(
     }
     sqlite3DbFree(db, aiCol);
 
-    /* If pTab->dbMem==0, then the table may be part of a shared-schema.
-    ** Disable the lookaside buffer before allocating space for the
-    ** trigger definition in this case.  */
+    /* In the current implementation, pTab->dbMem==0 for all tables except
+    ** for temporary tables used to describe subqueries.  And temporary
+    ** tables do not have foreign key constraints.  Hence, pTab->dbMem
+    ** should always be 0 there.
+    */
     enableLookaside = db->lookaside.bEnabled;
-    if( pTab->dbMem==0 ){
+    if( ALWAYS(pTab->dbMem==0) ){
       db->lookaside.bEnabled = 0;
     }
 

src/sqliteInt.h

@@ -1283,9 +1283,9 @@ struct Table {
 ** the from-table is created.  The existence of the to-table is not checked.
 */
 struct FKey {
-  Table *pFrom;     /* The table that contains the REFERENCES clause */
+  Table *pFrom;     /* Table containing the REFERENCES clause (aka: Child) */
   FKey *pNextFrom;  /* Next foreign key in pFrom */
-  char *zTo;        /* Name of table that the key points to */
+  char *zTo;        /* Name of table that the key points to (aka: Parent) */
   FKey *pNextTo;    /* Next foreign key on table named zTo */
   FKey *pPrevTo;    /* Previous foreign key on table named zTo */
   int nCol;         /* Number of columns in this key */