Update comments in where.c. No code changes. (CVS 2727)

FossilOrigin-Name: bb84d27eda64479d65b13fbbcaeef6a00da4d103

manifest

@@ -1,5 +1,5 @@
-C Documentation\supdates.\s(CVS\s2726)
-D 2005-09-20T01:36:30
+C Update\scomments\sin\swhere.c.\s\sNo\scode\schanges.\s(CVS\s2727)
+D 2005-09-20T08:47:20
 F Makefile.in 12784cdce5ffc8dfb707300c34e4f1eb3b8a14f1
 F Makefile.linux-gcc 06be33b2a9ad4f005a5f42b22c4a19dab3cbb5c7
 F README 9c4e2d6706bdcc3efdd773ce752a8cdab4f90028
@@ -87,7 +87,7 @@ F src/vdbeapi.c 85bbe1d0243a89655433d60711b4bd71979b59cd
 F src/vdbeaux.c 57a6ced8417bdc6f06c391d9c560ecbbed644ef3
 F src/vdbefifo.c 9efb94c8c3f4c979ebd0028219483f88e57584f5
 F src/vdbemem.c fea0744936008831daa17cdc75056c3ca1469690
-F src/where.c 2b7b4dd112a027021d9c53e25d221761d572a925
+F src/where.c 363b4fb0aee9fe69367ceaab0974dafa4e4ab900
 F tclinstaller.tcl 046e3624671962dc50f0481d7c25b38ef803eb42
 F test/all.test 7f0988442ab811dfa41793b5b550f5828ce316f3
 F test/alter.test 9d6837a3d946b73df692b7cef2a7644d2e2f6bc6
@@ -311,7 +311,7 @@ F www/tclsqlite.tcl ddcf912ea48695603c8ed7efb29f0812ef8d1b49
 F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
 F www/version3.tcl a99cf5f6d8bd4d5537584a2b342f0fb9fa601d8b
 F www/whentouse.tcl 97e2b5cd296f7d8057e11f44427dea8a4c2db513
-P ea10f9785e3c5248dafcc297f3a2c5465b6e0dba
-R 6ad171a801eb8b84ac88c34ad2f04d27
+P 6ec8883c366532948e619830ff7d9f63b79fc08b
+R 83e2318d245416067a9bf94d66214656
 U drh
-Z 23a34f97623654d558cd9b041aa96deb
+Z 7b8f65438258711df695628d2834385c

manifest.uuid

@@ -1 +1 @@
-6ec8883c366532948e619830ff7d9f63b79fc08b
+bb84d27eda64479d65b13fbbcaeef6a00da4d103

src/where.c

@@ -16,7 +16,7 @@
 ** so is applicable.  Because this module is responsible for selecting
 ** indices, you might also think of this module as the "query optimizer".
 **
-** $Id: where.c,v 1.177 2005/09/19 21:05:49 drh Exp $
+** $Id: where.c,v 1.178 2005/09/20 08:47:20 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -232,7 +232,7 @@ static int whereClauseInsert(WhereClause *pWC, Expr *p, int flags){
 
 /*
 ** This routine identifies subexpressions in the WHERE clause where
-** each subexpression is separate by the AND operator or some other
+** each subexpression is separated by the AND operator or some other
 ** operator specified in the op parameter.  The WhereClause structure
 ** is filled with pointers to subexpressions.  For example:
 **
@@ -281,7 +281,7 @@ static Bitmask getMask(ExprMaskSet *pMaskSet, int iCursor){
 **
 ** There is one cursor per table in the FROM clause.  The number of
 ** tables in the FROM clause is limited by a test early in the
-** sqlite3WhereBegin() routien.  So we know that the pMaskSet->ix[]
+** sqlite3WhereBegin() routine.  So we know that the pMaskSet->ix[]
 ** array will never overflow.
 */
 static void createMask(ExprMaskSet *pMaskSet, int iCursor){
@@ -532,7 +532,7 @@ static int isLikeOrGlob(
 ** to the standard form of "X <op> <expr>".  If the expression is of
 ** the form "X <op> Y" where both X and Y are columns, then the original
 ** expression is unchanged and a new virtual expression of the form
-** "Y <op> X" is added to the WHERE clause.  
+** "Y <op> X" is added to the WHERE clause and analyzed separately.
 */
 static void exprAnalyze(
   SrcList *pSrc,            /* the FROM clause */
@@ -847,7 +847,7 @@ static int sortableByRowid(
 }
 
 /*
-** Prepare a crude estimate of the logorithm of the input value.
+** Prepare a crude estimate of the logarithm of the input value.
 ** The results need not be exact.  This is only used for estimating
 ** the total cost of performing operatings with O(logN) or O(NlogN)
 ** complexity.  Because N is just a guess, it is no great tragedy if
@@ -1106,11 +1106,12 @@ static double bestIndex(
 ** of a LEFT OUTER JOIN.  In (1), the term is not disabled.
 **
 ** Disabling a term causes that term to not be tested in the inner loop
-** of the join.  Disabling is an optimization.  We would get the correct
-** results if nothing were ever disabled, but joins might run a little
-** slower.  The trick is to disable as much as we can without disabling
-** too much.  If we disabled in (1), we'd get the wrong answer.
-** See ticket #813.
+** of the join.  Disabling is an optimization.  When terms are satisfied
+** by indices, we disable them to prevent redundant tests in the inner
+** loop.  We would get the correct results if nothing were ever disabled,
+** but joins might run a little slower.  The trick is to disable as much
+** as we can without disabling too much.  If we disabled in (1), we'd get
+** the wrong answer.  See ticket #813.
 */
 static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){
   if( pTerm
@@ -1425,7 +1426,7 @@ WhereInfo *sqlite3WhereBegin(
   /* Analyze all of the subexpressions.  Note that exprAnalyze() might
   ** add new virtual terms onto the end of the WHERE clause.  We do not
   ** want to analyze these virtual terms, so start analyzing at the end
-  ** and work forward so that they added virtual terms are never processed.
+  ** and work forward so that the added virtual terms are never processed.
   */
   for(i=0; i<pTabList->nSrc; i++){
     createMask(&maskSet, pTabList->a[i].iCursor);