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In sqlite3FindInIndex(), improve internal comments and avoid an

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unreachable branch.

FossilOrigin-Name: 55945fc12f8157e32e6850e41575c0c6422d29e7
This commit is contained in:
drh
2016-08-24 18:51:23 +00:00
parent 321e828d03
commit 62659b2a80
3 changed files with 19 additions and 11 deletions
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16
src/expr.c
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@@ -2152,6 +2152,7 @@ int sqlite3FindInIndex(
*/
assert(v);
if( nExpr==1 && pEList->a[0].pExpr->iColumn<0 ){
/* The "x IN (SELECT rowid FROM table)" case */
int iAddr = sqlite3CodeOnce(pParse);
VdbeCoverage(v);
@@ -2165,18 +2166,25 @@ int sqlite3FindInIndex(
int i;
/* Check that the affinity that will be used to perform each
** comparison is the same as the affinity of each column. If
** it not, it is not possible to use any index. */
** comparison is the same as the affinity of each column in table
** on the RHS of the IN operator. If it not, it is not possible to
** use any index of the RHS table. */
for(i=0; i<nExpr && affinity_ok; i++){
Expr *pLhs = sqlite3VectorFieldSubexpr(pX->pLeft, i);
int iCol = pEList->a[i].pExpr->iColumn;
char idxaff = pTab->aCol[iCol].affinity;
char idxaff = pTab->aCol[iCol].affinity; /* RHS table affinity */
char cmpaff = sqlite3CompareAffinity(pLhs, idxaff);
testcase( cmpaff==SQLITE_AFF_BLOB );
testcase( cmpaff==SQLITE_AFF_TEXT );
switch( cmpaff ){
case SQLITE_AFF_BLOB:
break;
case SQLITE_AFF_TEXT:
affinity_ok = (idxaff==SQLITE_AFF_TEXT);
/* sqlite3CompareAffinity() only returns TEXT if one side or the
** other has no affinity and the other side is TEXT. Hence,
** the only way for cmpaff to be TEXT is for idxaff to be TEXT
** and for the term on the LHS of the IN to have no affinity. */
assert( idxaff==SQLITE_AFF_TEXT );
break;
default:
affinity_ok = sqlite3IsNumericAffinity(idxaff);