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Overview
| Comment: | Reduce the number of branches that need to be tested in the explainIndexRange() function of where.c. |
|---|---|
| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | experimental |
| Files: | files | file ages | folders |
| SHA1: |
6fdae9a635a43e1bf7e4a480de141306 |
| User & Date: | drh 2010-11-12 15:36:00.000 |
Context
|
2010-11-12
| ||
| 17:41 | Add EXPLAIN QUERY PLAN test cases to check that the examples in the documentation work. (check-in: 85fdad850a user: dan tags: experimental) | |
| 15:36 | Reduce the number of branches that need to be tested in the explainIndexRange() function of where.c. (check-in: 6fdae9a635 user: drh tags: experimental) | |
|
2010-11-11
| ||
| 17:48 | Use "COMPOUND" instead of "COMPOSITE" in the EXPLAIN QUERY PLAN output to describe UNION, UNION ALL, EXCEPT and INTERSECT operations. (check-in: 28643b85d9 user: dan tags: experimental) | |
Changes
Changes to src/where.c.
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3127 3128 3129 3130 3131 3132 3133 3134 3135 3136 3137 3138 3139 3140 |
}
}
*pzAff = zAff;
return regBase;
}
#ifndef SQLITE_OMIT_EXPLAIN
/*
** Argument pLevel describes a strategy for scanning table pTab. This
** function returns a pointer to a string buffer containing a description
** of the subset of table rows scanned by the strategy in the form of an
** SQL expression. Or, if all rows are scanned, NULL is returned.
**
** For example, if the query:
| > > > > > > > > > > > > > > > > > > > > | 3127 3128 3129 3130 3131 3132 3133 3134 3135 3136 3137 3138 3139 3140 3141 3142 3143 3144 3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 |
}
}
*pzAff = zAff;
return regBase;
}
#ifndef SQLITE_OMIT_EXPLAIN
/*
** This routine is a helper for explainIndexRange() below
**
** pStr holds the text of an expression that we are building up one term
** at a time. This routine adds a new term to the end of the expression.
** Terms are separated by AND so add the "AND" text for second and subsequent
** terms only.
*/
static void explainAppendTerm(
StrAccum *pStr, /* The text expression being built */
int iTerm, /* Index of this term. First is zero */
const char *zColumn, /* Name of the column */
const char *zOp /* Name of the operator */
){
if( iTerm ) sqlite3StrAccumAppend(pStr, " AND ", 5);
sqlite3StrAccumAppend(pStr, zColumn, -1);
sqlite3StrAccumAppend(pStr, zOp, 1);
sqlite3StrAccumAppend(pStr, "?", 1);
}
/*
** Argument pLevel describes a strategy for scanning table pTab. This
** function returns a pointer to a string buffer containing a description
** of the subset of table rows scanned by the strategy in the form of an
** SQL expression. Or, if all rows are scanned, NULL is returned.
**
** For example, if the query:
|
| ︙ | ︙ | |||
3150 3151 3152 3153 3154 3155 3156 |
** It is the responsibility of the caller to free the buffer when it is
** no longer required.
*/
static char *explainIndexRange(sqlite3 *db, WhereLevel *pLevel, Table *pTab){
WherePlan *pPlan = &pLevel->plan;
Index *pIndex = pPlan->u.pIdx;
int nEq = pPlan->nEq;
| < | > > > > > > > > < < | < > < < | < < < < < < | < < | | | 3170 3171 3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 |
** It is the responsibility of the caller to free the buffer when it is
** no longer required.
*/
static char *explainIndexRange(sqlite3 *db, WhereLevel *pLevel, Table *pTab){
WherePlan *pPlan = &pLevel->plan;
Index *pIndex = pPlan->u.pIdx;
int nEq = pPlan->nEq;
int i, j;
Column *aCol = pTab->aCol;
int *aiColumn = pIndex->aiColumn;
StrAccum txt;
if( nEq==0 && (pPlan->wsFlags & (WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))==0 ){
return 0;
}
sqlite3StrAccumInit(&txt, 0, 0, SQLITE_MAX_LENGTH);
sqlite3StrAccumAppend(&txt, " (", 2);
for(i=0; i<nEq; i++){
explainAppendTerm(&txt, i, aCol[aiColumn[i]].zName, "=");
}
j = i;
if( pPlan->wsFlags&WHERE_BTM_LIMIT ){
explainAppendTerm(&txt, i++, aCol[aiColumn[j]].zName, ">");
}
if( pPlan->wsFlags&WHERE_TOP_LIMIT ){
explainAppendTerm(&txt, i, aCol[aiColumn[j]].zName, "<");
}
sqlite3StrAccumAppend(&txt, ")", 1);
return sqlite3StrAccumFinish(&txt);
}
/*
** This function is a no-op unless currently processing an EXPLAIN QUERY PLAN
** command. If the query being compiled is an EXPLAIN QUERY PLAN, a single
** record is added to the output to describe the table scan strategy in
** pLevel.
|
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