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Use a hash table to improve the preformance of column name uniqueness checking.

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FossilOrigin-Name: 5b08f29f458c600401860c7d70d8174cf61e69f8
This commit is contained in:
drh 2015-11-14 20:52:43 +00:00
parent ebed3fa3e1
commit 0315e3cc14
3 changed files with 25 additions and 27 deletions
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12
manifest
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@ -1,5 +1,5 @@
C Use\srandomness\sto\sprevent\sshowness\sin\sthe\sgenerated-column-name\suniqueness\nchecking.
D 2015-11-14T16:47:23.463
C Use\sa\shash\stable\sto\simprove\sthe\spreformance\sof\scolumn\sname\suniqueness\schecking.
D 2015-11-14T20:52:43.849
F Makefile.in d828db6afa6c1fa060d01e33e4674408df1942a1
F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
F Makefile.msc e928e68168df69b353300ac87c10105206653a03
@ -339,7 +339,7 @@ F src/printf.c 0c4bcdd1c2e2521024f0a69cb5eb334f86b3652a
F src/random.c ba2679f80ec82c4190062d756f22d0c358180696
F src/resolve.c 1954a0f01bf65d78d7d559aea3d5c67f33376d91
F src/rowset.c eccf6af6d620aaa4579bd3b72c1b6395d9e9fa1e
F src/select.c 7ef4a946893f171920843d4d8c30c2544a060fbe
F src/select.c d5878c33d9bb66c82b2b7773731bf290248763bb
F src/shell.c acefb4593a9bf0338a757c968f1f1bb05690d830
F src/sqlite.h.in fa62718f73553f06b2f2e362fd09ccb4e1cbb626
F src/sqlite3.rc 992c9f5fb8285ae285d6be28240a7e8d3a7f2bad
@ -1403,7 +1403,7 @@ F tool/vdbe_profile.tcl 246d0da094856d72d2c12efec03250d71639d19f
F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
F tool/warnings.sh 48bd54594752d5be3337f12c72f28d2080cb630b
F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
P dfd6d9f4fbe902086f9158dfa5f37e781765a683
R f75d239f0c3cc028f9c3bdc5405581af
P 6266712968a2cdcd6f5a3007d60c2cf1b3faf912
R 7d9535e63307ca117e4aa92e0ee4dc2c
U drh
Z df73d438cc87e48519d39f020060cfa5
Z d8b237007fcc1a03b5ce77808531ddb1

2
manifest.uuid
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@ -1 +1 @@
6266712968a2cdcd6f5a3007d60c2cf1b3faf912
5b08f29f458c600401860c7d70d8174cf61e69f8

38
src/select.c
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@ -1602,7 +1602,9 @@ int sqlite3ColumnsFromExprList(
Expr *p; /* Expression for a single result column */
char *zName; /* Column name */
int nName; /* Size of name in zName[] */
Hash ht; /* Hash table of column names */
sqlite3HashInit(&ht);
if( pEList ){
nCol = pEList->nExpr;
aCol = sqlite3DbMallocZero(db, sizeof(aCol[0])*nCol);
@ -1614,7 +1616,7 @@ int sqlite3ColumnsFromExprList(
*pnCol = nCol;
*paCol = aCol;
for(i=0, pCol=aCol; i<nCol; i++, pCol++){
for(i=0, pCol=aCol; i<nCol && !db->mallocFailed; i++, pCol++){
/* Get an appropriate name for the column
*/
p = sqlite3ExprSkipCollate(pEList->a[i].pExpr);
@ -1643,32 +1645,28 @@ int sqlite3ColumnsFromExprList(
zName = sqlite3MPrintf(db, "%s", pEList->a[i].zSpan);
}
}
if( db->mallocFailed ){
sqlite3DbFree(db, zName);
break;
}
/* Make sure the column name is unique. If the name is not unique,
** append an integer to the name so that it becomes unique.
*/
nName = sqlite3Strlen30(zName);
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);
}
cnt = 0;
while( zName && sqlite3HashFind(&ht, zName)!=0 ){
char *zNewName;
nName = sqlite3Strlen30(zName);
for(j=nName-1; j>0 && sqlite3Isdigit(zName[j]); j--){}
if( zName[j]==':' ) nName = j;
zName[nName] = 0;
zNewName = sqlite3MPrintf(db, "%s:%u", zName, ++cnt);
sqlite3DbFree(db, zName);
zName = zNewName;
if( cnt>3 ) sqlite3_randomness(sizeof(cnt), &cnt);
}
pCol->zName = zName;
if( zName && sqlite3HashInsert(&ht, zName, pCol)==pCol ){
db->mallocFailed = 1;
}
}
sqlite3HashClear(&ht);
if( db->mallocFailed ){
for(j=0; j<i; j++){
sqlite3DbFree(db, aCol[j].zName);