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Overview
| Comment: | Use randomness to prevent slowness in the generated-column-name uniqueness checking. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: | 6266712968a2cdcd6f5a3007d60c2cf1 |
| User & Date: | drh 2015-11-14 16:47:23 |
| Original Comment: | Use randomness to prevent showness in the generated-column-name uniqueness checking. |
Context
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2015-11-14
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| 20:52 | Use a hash table to improve the preformance of column name uniqueness checking. check-in: 5b08f29f user: drh tags: trunk | |
| 16:47 | Use randomness to prevent slowness in the generated-column-name uniqueness checking. check-in: 62667129 user: drh tags: trunk | |
|
2015-11-13
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| 20:52 | Fix a memory leak in the fuzzcheck utility. check-in: dfd6d9f4 user: drh tags: trunk | |
Changes
Changes to src/select.c.
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Parse *pParse, /* Parsing context */
ExprList *pEList, /* Expr list from which to derive column names */
i16 *pnCol, /* Write the number of columns here */
Column **paCol /* Write the new column list here */
){
sqlite3 *db = pParse->db; /* Database connection */
int i, j; /* Loop counters */
int cnt; /* Index added to make the name unique */
Column *aCol, *pCol; /* For looping over result columns */
int nCol; /* Number of columns in the result set */
Expr *p; /* Expression for a single result column */
char *zName; /* Column name */
int nName; /* Size of name in zName[] */
if( pEList ){
................................................................................
for(j=cnt=0; j<i; j++){
if( sqlite3StrICmp(aCol[j].zName, zName)==0 ){
char *zNewName;
int k;
for(k=nName-1; k>1 && sqlite3Isdigit(zName[k]); k--){}
if( k>=0 && zName[k]==':' ) nName = k;
zName[nName] = 0;
zNewName = sqlite3MPrintf(db, "%s:%d", zName, ++cnt);
sqlite3DbFree(db, zName);
zName = zNewName;
j = -1;
if( zName==0 ) break;
}
}
pCol->zName = zName;
}
if( db->mallocFailed ){
for(j=0; j<i; j++){
sqlite3DbFree(db, aCol[j].zName);
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Parse *pParse, /* Parsing context */
ExprList *pEList, /* Expr list from which to derive column names */
i16 *pnCol, /* Write the number of columns here */
Column **paCol /* Write the new column list here */
){
sqlite3 *db = pParse->db; /* Database connection */
int i, j; /* Loop counters */
u32 cnt; /* Index added to make the name unique */
Column *aCol, *pCol; /* For looping over result columns */
int nCol; /* Number of columns in the result set */
Expr *p; /* Expression for a single result column */
char *zName; /* Column name */
int nName; /* Size of name in zName[] */
if( pEList ){
................................................................................
for(j=cnt=0; j<i; j++){
if( sqlite3StrICmp(aCol[j].zName, zName)==0 ){
char *zNewName;
int k;
for(k=nName-1; k>1 && sqlite3Isdigit(zName[k]); k--){}
if( k>=0 && zName[k]==':' ) nName = k;
zName[nName] = 0;
zNewName = sqlite3MPrintf(db, "%s:%u", zName, ++cnt);
sqlite3DbFree(db, zName);
zName = zNewName;
j = -1;
if( zName==0 ) break;
if( cnt>3 ) sqlite3_randomness(sizeof(cnt), &cnt);
}
}
pCol->zName = zName;
}
if( db->mallocFailed ){
for(j=0; j<i; j++){
sqlite3DbFree(db, aCol[j].zName);
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