Fix typos and add clarification to comments in where.c. No code changes.

FossilOrigin-Name: f8d8790ede0fcaf6c5b60ac22919c1d97c74e838

manifest

@@ -1,5 +1,5 @@
-C Fix\sa\stest\scase\srelated\sto\spartial\sindices\sso\sthat\sit\sworks\seven\sif\nSTAT3\sis\sdisabled.
+C Fix\stypos\sand\sadd\sclarification\sto\scomments\sin\swhere.c.\s\sNo\scode\schanges.
-D 2013-08-06T19:18:17.913
+D 2013-08-07T01:18:38.449
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 5e41da95d92656a5004b03d3576e8b226858a28e
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -290,7 +290,7 @@ F src/vtab.c 2e8b489db47e20ae36cd247932dc671c9ded0624
 F src/wal.c 7dc3966ef98b74422267e7e6e46e07ff6c6eb1b4
 F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
 F src/walker.c 4fa43583d0a84b48f93b1e88f11adf2065be4e73
-F src/where.c 67245bb73fd9cc04ee7796a0f358d4910c45cfe9
+F src/where.c ea01a52eb31e54dda97b8e39c2e5b38faa13dce5
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
 F test/aggnested.test 45c0201e28045ad38a530b5a144b73cd4aa2cfd6
@@ -1105,7 +1105,7 @@ F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381
 F tool/wherecosttest.c f407dc4c79786982a475261866a161cd007947ae
 F tool/win/sqlite.vsix 97894c2790eda7b5bce3cc79cb2a8ec2fde9b3ac
-P 89930ea3c3b3bd078f641b2c5203d851083bbf1a
+P 153c645025637bbff14dfce793e4b92210ded7e8
-R 22d053337a8290c9ac6b0d4c1264f844
+R bd41820faa238dc5341c3c2a4f14484a
 U drh
-Z 21ef7545513488fc6735d995a8f856cc
+Z dce4447dee7fcad2bdba25f503c8b865

manifest.uuid

@@ -1 +1 @@
-153c645025637bbff14dfce793e4b92210ded7e8
+f8d8790ede0fcaf6c5b60ac22919c1d97c74e838

src/where.c

@@ -33,7 +33,7 @@
 # define WHERETRACE(K,X)
 #endif
 
-/* Forward reference
+/* Forward references
 */
 typedef struct WhereClause WhereClause;
 typedef struct WhereMaskSet WhereMaskSet;
@@ -55,14 +55,15 @@ typedef struct WhereOrSet WhereOrSet;
 ** So all costs can be stored in a 16-bit unsigned integer without risk
 ** of overflow.
 **
-** Costs are estimates, so don't go to the computational trouble to compute
+** Costs are estimates, so no effort is made to compute 10*log2(X) exactly.
-** 10*log2(X) exactly.  Instead, a close estimate is used.  Any value of
+** Instead, a close estimate is used.  Any value of X<=1 is stored as 0.
-** X<=1 is stored as 0.  X=2 is 10.  X=3 is 16.  X=1000 is 99. etc.
+** X=2 is 10.  X=3 is 16.  X=1000 is 99. etc.
 **
 ** The tool/wherecosttest.c source file implements a command-line program
-** that will convert between WhereCost to integers and do addition and
+** that will convert WhereCosts to integers, convert integers to WhereCosts
-** multiplication on WhereCost values.  That command-line program is a
+** and do addition and multiplication on WhereCost values.  The wherecosttest
-** useful utility to have around when working with this module.
+** command-line program is a useful utility to have around when working with
+** this module.
 */
 typedef unsigned short int WhereCost;
 
@@ -165,8 +166,8 @@ struct WhereOrCost {
 };
 
 /* The WhereOrSet object holds a set of possible WhereOrCosts that
-** correspond to the subquery(s) of OR-clause processing.  At most
+** correspond to the subquery(s) of OR-clause processing.  Only the
-** favorable N_OR_COST elements are retained.
+** best N_OR_COST elements are retained.
 */
 #define N_OR_COST 3
 struct WhereOrSet {
@@ -232,9 +233,9 @@ struct WherePath {
 **
 **         (t1.X <op> <expr>) OR (t1.Y <op> <expr>) OR ....
 **
-** In this second case, wtFlag as the TERM_ORINFO set and eOperator==WO_OR
+** In this second case, wtFlag has the TERM_ORINFO bit set and eOperator==WO_OR
 ** and the WhereTerm.u.pOrInfo field points to auxiliary information that
-** is collected about the
+** is collected about the OR clause.
 **
 ** If a term in the WHERE clause does not match either of the two previous
 ** categories, then eOperator==0.  The WhereTerm.pExpr field is still set
@@ -746,7 +747,7 @@ static void createMask(WhereMaskSet *pMaskSet, int iCursor){
 }
 
 /*
-** These routine walk (recursively) an expression tree and generates
+** These routines walk (recursively) an expression tree and generate
 ** a bitmask indicating which tables are used in that expression
 ** tree.
 */
@@ -1263,10 +1264,10 @@ static void transferJoinMarkings(Expr *pDerived, Expr *pBase){
 ** From another point of view, "indexable" means that the subterm could
 ** potentially be used with an index if an appropriate index exists.
 ** This analysis does not consider whether or not the index exists; that
-** is something the bestIndex() routine will determine.  This analysis
+** is decided elsewhere.  This analysis only looks at whether subterms
-** only looks at whether subterms appropriate for indexing exist.
+** appropriate for indexing exist.
 **
-** All examples A through E above all satisfy case 2.  But if a term
+** All examples A through E above satisfy case 2.  But if a term
 ** also statisfies case 1 (such as B) we know that the optimizer will
 ** always prefer case 1, so in that case we pretend that case 2 is not
 ** satisfied.
@@ -1933,7 +1934,7 @@ static int isDistinctRedundant(
 }
 
 /* 
-** The (an approximate) sum of two WhereCosts.  This computation is
+** Find (an approximate) sum of two WhereCosts.  This computation is
 ** not a simple "+" operator because WhereCost is stored as a logarithmic
 ** value.
 **