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Further minor comment corrections and enhancements in where.c.

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FossilOrigin-Name: 0d68d4d018e73dcbbc08786071aac6228fca1a8c
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drh
2013-07-01 11:05:50 +00:00
parent be4fe3afc0
commit 9443342ee9
3 changed files with 18 additions and 10 deletions
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14
src/where.c
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@@ -4428,7 +4428,7 @@ static Bitmask columnsInIndex(Index *pIdx){
/*
** Add all WhereLoop objects a single table of the join were the table
** Add all WhereLoop objects for a single table of the join were the table
** is idenfied by pBuilder->pNew->iTab. That table is guaranteed to be
** a b-tree table, not a virtual table.
*/
@@ -4892,12 +4892,19 @@ static int whereLoopAddAll(WhereLoopBuilder *pBuilder){
/*
** Examine a WherePath (with the addition of the extra WhereLoop of the 5th
** parameters) to see if it outputs rows in the requested ORDER BY
** (or GROUP BY) without requiring a separate source operation. Return:
** (or GROUP BY) without requiring a separate sort operation. Return:
**
** 0: ORDER BY is not satisfied. Sorting required
** 1: ORDER BY is satisfied. Omit sorting
** -1: Unknown at this time
**
** Note that processing for WHERE_GROUPBY and WHERE_DISTINCTBY is not as
** strict. With GROUP BY and DISTINCT the only requirement is that
** equivalent rows appear immediately adjacent to one another. GROUP BY
** and DISTINT do not require rows to appear in any particular order as long
** as equivelent rows are grouped together. Thus for GROUP BY and DISTINCT
** the pOrderBy terms can be matched in any order. With ORDER BY, the
** pOrderBy terms must be matched in strict left-to-right order.
*/
static int wherePathSatisfiesOrderBy(
WhereInfo *pWInfo, /* The WHERE clause */
@@ -5562,7 +5569,8 @@ static int whereShortCut(WhereLoopBuilder *pBuilder){
**
** ORDER BY CLAUSE PROCESSING
**
** pOrderBy is a pointer to the ORDER BY clause of a SELECT statement,
** pOrderBy is a pointer to the ORDER BY clause (or the GROUP BY clause
** if the WHERE_GROUPBY flag is set in wctrlFlags) of a SELECT statement
** if there is one. If there is no ORDER BY clause or if this routine
** is called from an UPDATE or DELETE statement, then pOrderBy is NULL.
*/