Refactor the LIKE optimization decision logic so that it uses

sqlite3AtoF() on both boundary keys to determine if the optimization can be
used when the LHS is something that might not have TEXT affinity.
Ticket [ce8717f0885af975].  See also [c94369cae9b561b1],
[b043a54c3de54b28], [fd76310a5e843e07], and [158290c0abafde67].

FossilOrigin-Name: b4a9e09e60213ccff925d09f0b6e549e2a3e3862856c710f108779e2867dec76

1 files changed, 22 insertions, 19 deletions

diff --git a/src/whereexpr.c b/src/whereexpr.c
index db460652c..9ac940c5a 100644
--- a/src/whereexpr.c
+++ b/src/whereexpr.c
@@ -264,28 +264,31 @@ static int isLikeOrGlob(
         zNew[iTo] = 0;
         assert( iTo>0 );
 
-        /* If the RHS begins with a digit, a +/- sign or whitespace, then the
-        ** LHS must be an ordinary column (not a virtual table column) with
-        ** TEXT affinity. Otherwise the LHS might be numeric and "lhs >= rhs"
-        ** would be false even though "lhs LIKE rhs" is true.  But if the RHS
-        ** does not start with a digit or +/-, then "lhs LIKE rhs" will always
-        ** be false if the LHS is numeric and so the optimization still works.
+        /* If the LHS is not an ordinary column with TEXT affinity, then the
+        ** pattern prefix boundaries (both the start and end boundaries) must
+        ** not look like a number.  Otherwise the pattern might be treated as
+        ** a number, which will invalidate the LIKE optimization.
         **
-        ** 2018-09-10 ticket c94369cae9b561b1f996d0054bfab11389f9d033
-        ** The RHS pattern must not be '/%' because the termination condition
-        ** will then become "x<'0'" and if the affinity is numeric, will then
-        ** be converted into "x<0", which is incorrect.
+        ** Getting this right has been a persistent source of bugs in the
+        ** LIKE optimization.  See, for example:
+        **    2018-09-10 https://sqlite.org/src/info/c94369cae9b561b1
+        **    2019-05-02 https://sqlite.org/src/info/b043a54c3de54b28
+        **    2019-06-10 https://sqlite.org/src/info/fd76310a5e843e07
+        **    2019-06-14 https://sqlite.org/src/info/ce8717f0885af975
         */
-        if( sqlite3Isdigit(zNew[0])
-         || sqlite3Isspace(zNew[0])
-         || zNew[0]=='-'
-         || zNew[0]=='+'
-         || zNew[iTo-1]=='0'-1
+        if( pLeft->op!=TK_COLUMN 
+         || sqlite3ExprAffinity(pLeft)!=SQLITE_AFF_TEXT 
+         || IsVirtual(pLeft->y.pTab)  /* Value might be numeric */
         ){
-          if( pLeft->op!=TK_COLUMN 
-           || sqlite3ExprAffinity(pLeft)!=SQLITE_AFF_TEXT 
-           || IsVirtual(pLeft->y.pTab)  /* Value might be numeric */
-          ){
+          int isNum;
+          double rDummy;
+          isNum = sqlite3AtoF(zNew, &rDummy, iTo, SQLITE_UTF8);
+          if( isNum<=0 ){
+            zNew[iTo-1]++;
+            isNum = sqlite3AtoF(zNew, &rDummy, iTo, SQLITE_UTF8);
+            zNew[iTo-1]--;
+          }
+          if( isNum>0 ){
             sqlite3ExprDelete(db, pPrefix);
             sqlite3ValueFree(pVal);
             return 0;