database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2025-11-16 23:02:26 +03:00
Code Activity

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

Browse Source 
FossilOrigin-Name: bb84d27eda64479d65b13fbbcaeef6a00da4d103
This commit is contained in:
drh
2005-09-20 08:47:20 +00:00
parent e1547a2f1c
commit b6fb62d9b4
3 changed files with 19 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
src/where.c
View File

@@ -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);