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The xTruncate method for the multiplexor now changes surplus overflow

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files to zero-length by default.  Or if the "truncate" query parameter 
is used, it actually deletes the surplus overflow files.  This allows
VACUUM to shrink the database again.

FossilOrigin-Name: 5aefef04d6cc3b734c3f05e036b3869a52248f4d
This commit is contained in:
drh
2011-12-16 04:57:32 +00:00
parent 38deeb9763
commit e7d9f13d99
3 changed files with 103 additions and 79 deletions
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168
src/test_multiplex.c
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@@ -133,7 +133,8 @@ struct multiplexGroup {
int nName; /* Length of base filename */
int flags; /* Flags used for original opening */
unsigned int szChunk; /* Chunk size used for this group */
int bEnabled; /* TRUE to use Multiplex VFS for this file */
unsigned char bEnabled; /* TRUE to use Multiplex VFS for this file */
unsigned char bTruncate; /* TRUE to enable truncation of databases */
multiplexGroup *pNext, *pPrev; /* Doubly linked list of all group objects */
};
@@ -276,12 +277,17 @@ static int multiplexSubFilename(multiplexGroup *pGroup, int iChunk){
/* Translate an sqlite3_file* that is really a multiplexGroup* into
** the sqlite3_file* for the underlying original VFS.
**
** For chunk 0, the pGroup->flags determines whether or not a new file
** is created if it does not already exist. For chunks 1 and higher, the
** file is created only if createFlag is 1.
*/
static sqlite3_file *multiplexSubOpen(
multiplexGroup *pGroup,
int iChunk,
int *rc,
int *pOutFlags
multiplexGroup *pGroup, /* The multiplexor group */
int iChunk, /* Which chunk to open. 0==original file */
int *rc, /* Result code in and out */
int *pOutFlags, /* Output flags */
int createFlag /* True to create if iChunk>0 */
){
sqlite3_file *pSubOpen = 0;
sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs; /* Real VFS */
@@ -299,15 +305,28 @@ static sqlite3_file *multiplexSubOpen(
*rc = multiplexSubFilename(pGroup, iChunk);
if( (*rc)==SQLITE_OK && (pSubOpen = pGroup->aReal[iChunk].p)==0 ){
int flags, rc2, bExists;
if( iChunk==0 ) createFlag = (pGroup->flags & SQLITE_OPEN_CREATE)!=0;
flags = pGroup->flags;
if( createFlag ){
flags |= SQLITE_OPEN_CREATE;
}else if( pGroup->aReal[iChunk].z==0 ){
return 0;
}else{
*rc = pOrigVfs->xAccess(pOrigVfs, pGroup->aReal[iChunk].z,
SQLITE_ACCESS_EXISTS, &bExists);
if( *rc || !bExists ) return 0;
flags &= ~SQLITE_OPEN_CREATE;
}
pSubOpen = sqlite3_malloc( pOrigVfs->szOsFile );
if( pSubOpen==0 ){
*rc = SQLITE_NOMEM;
return 0;
}
pGroup->aReal[iChunk].p = pSubOpen;
*rc = pOrigVfs->xOpen(pOrigVfs, pGroup->aReal[iChunk].z, pSubOpen,
pGroup->flags, pOutFlags);
if( *rc!=SQLITE_OK ){
rc2 = pOrigVfs->xOpen(pOrigVfs, pGroup->aReal[iChunk].z, pSubOpen,
flags, pOutFlags);
if( rc2!=SQLITE_OK ){
sqlite3_free(pSubOpen);
pGroup->aReal[iChunk].p = 0;
return 0;
@@ -316,6 +335,25 @@ static sqlite3_file *multiplexSubOpen(
return pSubOpen;
}
/*
** Return the size, in bytes, of chunk number iChunk. If that chunk
** does not exist, then return 0. This function does not distingish between
** non-existant files and zero-length files.
*/
static sqlite3_int64 multiplexSubSize(
multiplexGroup *pGroup, /* The multiplexor group */
int iChunk, /* Which chunk to open. 0==original file */
int *rc /* Result code in and out */
){
sqlite3_file *pSub;
sqlite3_int64 sz = 0;
pSub = multiplexSubOpen(pGroup, iChunk, rc, NULL, 0);
if( pSub==0 ) return 0;
*rc = pSub->pMethods->xFileSize(pSub, &sz);
return sz;
}
/*
** This is the implementation of the multiplex_control() SQL function.
*/
@@ -455,6 +493,7 @@ static int multiplexOpen(
memset(pGroup, 0, sz);
pMultiplexOpen->pGroup = pGroup;
pGroup->bEnabled = -1;
pGroup->bTruncate = (flags & SQLITE_OPEN_MAIN_DB)==0;
pGroup->szChunk = SQLITE_MULTIPLEX_CHUNK_SIZE;
if( zName ){
@@ -475,6 +514,7 @@ static int multiplexOpen(
pGroup->bEnabled = 0;
}
}
if( sqlite3_uri_parameter(zName, "truncate") ) pGroup->bTruncate = 1;
}
pGroup->zName = p;
memcpy(pGroup->zName, zName, nName+1);
@@ -493,8 +533,8 @@ static int multiplexOpen(
pGroup->flags = flags;
rc = multiplexSubFilename(pGroup, 1);
if( rc==SQLITE_OK ){
pSubOpen = multiplexSubOpen(pGroup, 0, &rc, pOutFlags);
assert( pSubOpen || rc!=SQLITE_OK );
pSubOpen = multiplexSubOpen(pGroup, 0, &rc, pOutFlags, 0);
if( pSubOpen==0 && rc==SQLITE_OK ) rc = SQLITE_CANTOPEN;
}
if( rc==SQLITE_OK ){
sqlite3_int64 sz;
@@ -522,17 +562,18 @@ static int multiplexOpen(
}
}else{
/* If the first overflow file exists and if the size of the main file
** is different from the chunk size, that means the chunk size is set
** set incorrectly. So fix it.
**
** Or, if the first overflow file does not exist and the main file is
** larger than the chunk size, that means the chunk size is too small.
** But we have no way of determining the intended chunk size, so
** just disable the multiplexor all togethre.
*/
** is different from the chunk size, that means the chunk size is set
** set incorrectly. So fix it.
**
** Or, if the first overflow file does not exist and the main file is
** larger than the chunk size, that means the chunk size is too small.
** But we have no way of determining the intended chunk size, so
** just disable the multiplexor all togethre.
*/
rc = pOrigVfs->xAccess(pOrigVfs, pGroup->aReal[1].z,
SQLITE_ACCESS_EXISTS, &bExists);
if( rc==SQLITE_OK && bExists && sz==(sz&0xffff0000) && sz>0
bExists = multiplexSubSize(pGroup, 1, &rc)>0;
if( rc==SQLITE_OK && bExists && sz==(sz&0xffff0000) && sz>0
&& sz!=pGroup->szChunk ){
pGroup->szChunk = sz;
}else if( rc==SQLITE_OK && !bExists && sz>pGroup->szChunk ){
@@ -674,7 +715,7 @@ static int multiplexRead(
int rc = SQLITE_OK;
multiplexEnter();
if( !pGroup->bEnabled ){
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL, 0);
if( pSubOpen==0 ){
rc = SQLITE_IOERR_READ;
}else{
@@ -683,7 +724,7 @@ static int multiplexRead(
}else{
while( iAmt > 0 ){
int i = (int)(iOfst / pGroup->szChunk);
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, i, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, i, &rc, NULL, 1);
if( pSubOpen ){
int extra = ((int)(iOfst % pGroup->szChunk) + iAmt) - pGroup->szChunk;
if( extra<0 ) extra = 0;
@@ -719,7 +760,7 @@ static int multiplexWrite(
int rc = SQLITE_OK;
multiplexEnter();
if( !pGroup->bEnabled ){
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL, 0);
if( pSubOpen==0 ){
rc = SQLITE_IOERR_WRITE;
}else{
@@ -728,7 +769,7 @@ static int multiplexWrite(
}else{
while( rc==SQLITE_OK && iAmt>0 ){
int i = (int)(iOfst / pGroup->szChunk);
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, i, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, i, &rc, NULL, 1);
if( pSubOpen ){
int extra = ((int)(iOfst % pGroup->szChunk) + iAmt) -
pGroup->szChunk;
@@ -756,28 +797,35 @@ static int multiplexTruncate(sqlite3_file *pConn, sqlite3_int64 size){
int rc = SQLITE_OK;
multiplexEnter();
if( !pGroup->bEnabled ){
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL, 0);
if( pSubOpen==0 ){
rc = SQLITE_IOERR_TRUNCATE;
}else{
rc = pSubOpen->pMethods->xTruncate(pSubOpen, size);
}
}else if( (pGroup->flags & SQLITE_OPEN_MAIN_DB)==0 ){
int rc2;
}else{
int i;
int iBaseGroup = (int)(size / pGroup->szChunk);
sqlite3_file *pSubOpen;
sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs; /* Real VFS */
/* delete the chunks above the truncate limit */
for(i=(int)(size / pGroup->szChunk)+1; i<pGroup->nReal; i++){
multiplexSubClose(pGroup, i, pOrigVfs);
for(i = pGroup->nReal-1; i>iBaseGroup && rc==SQLITE_OK; i--){
if( pGroup->bTruncate ){
multiplexSubClose(pGroup, i, pOrigVfs);
}else{
pSubOpen = multiplexSubOpen(pGroup, i, &rc, 0, 0);
if( pSubOpen ){
rc = pSubOpen->pMethods->xTruncate(pSubOpen, 0);
}
}
}
pSubOpen = multiplexSubOpen(pGroup, (int)(size/pGroup->szChunk), &rc2,0);
if( pSubOpen ){
rc2 = pSubOpen->pMethods->xTruncate(pSubOpen, size % pGroup->szChunk);
if( rc2!=SQLITE_OK ) rc = rc2;
}else{
rc = SQLITE_IOERR_TRUNCATE;
if( rc==SQLITE_OK ){
pSubOpen = multiplexSubOpen(pGroup, iBaseGroup, &rc, 0, 0);
if( pSubOpen ){
rc = pSubOpen->pMethods->xTruncate(pSubOpen, size % pGroup->szChunk);
}
}
if( rc ) rc = SQLITE_IOERR_TRUNCATE;
}
multiplexLeave();
return rc;
@@ -812,42 +860,18 @@ static int multiplexFileSize(sqlite3_file *pConn, sqlite3_int64 *pSize){
int i;
multiplexEnter();
if( !pGroup->bEnabled ){
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL, 0);
if( pSubOpen==0 ){
rc = SQLITE_IOERR_FSTAT;
}else{
rc = pSubOpen->pMethods->xFileSize(pSubOpen, pSize);
}
}else{
sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs;
*pSize = 0;
for(i=0; rc==SQLITE_OK; i++){
sqlite3_file *pSubOpen = 0;
int exists = 0;
rc = multiplexSubFilename(pGroup, i);
if( rc!=SQLITE_OK ) break;
if( pGroup->nReal>i && pGroup->aReal[i].p!=0 ){
exists = 1;
}else if( (pGroup->flags & SQLITE_OPEN_DELETEONCLOSE)==0 ){
const char *zReal = pGroup->aReal[i].z;
rc = pOrigVfs->xAccess(pOrigVfs, zReal, SQLITE_ACCESS_EXISTS, &exists);
}
if( exists==0 ){
/* stop at first "gap" or IO error. */
break;
}
if( rc==SQLITE_OK ){
pSubOpen = multiplexSubOpen(pGroup, i, &rc, NULL);
}
assert( pSubOpen || rc!=SQLITE_OK );
if( rc==SQLITE_OK ){
sqlite3_int64 sz = 0;
rc = pSubOpen->pMethods->xFileSize(pSubOpen, &sz);
if( rc==SQLITE_OK && sz>pGroup->szChunk ){
rc = SQLITE_IOERR_FSTAT;
}
*pSize = i*(sqlite3_int64)pGroup->szChunk + sz;
}
sqlite3_int64 sz = multiplexSubSize(pGroup, i, &rc);
if( sz==0 ) break;
*pSize = i*(sqlite3_int64)pGroup->szChunk + sz;
}
}
multiplexLeave();
@@ -859,7 +883,7 @@ static int multiplexFileSize(sqlite3_file *pConn, sqlite3_int64 *pSize){
static int multiplexLock(sqlite3_file *pConn, int lock){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL, 0);
if( pSubOpen ){
return pSubOpen->pMethods->xLock(pSubOpen, lock);
}
@@ -871,7 +895,7 @@ static int multiplexLock(sqlite3_file *pConn, int lock){
static int multiplexUnlock(sqlite3_file *pConn, int lock){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL, 0);
if( pSubOpen ){
return pSubOpen->pMethods->xUnlock(pSubOpen, lock);
}
@@ -883,7 +907,7 @@ static int multiplexUnlock(sqlite3_file *pConn, int lock){
static int multiplexCheckReservedLock(sqlite3_file *pConn, int *pResOut){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL, 0);
if( pSubOpen ){
return pSubOpen->pMethods->xCheckReservedLock(pSubOpen, pResOut);
}
@@ -931,7 +955,7 @@ static int multiplexFileControl(sqlite3_file *pConn, int op, void *pArg){
rc = SQLITE_OK;
break;
default:
pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL);
pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL, 0);
if( pSubOpen ){
rc = pSubOpen->pMethods->xFileControl(pSubOpen, op, pArg);
if( op==SQLITE_FCNTL_VFSNAME && rc==SQLITE_OK ){
@@ -948,7 +972,7 @@ static int multiplexFileControl(sqlite3_file *pConn, int op, void *pArg){
static int multiplexSectorSize(sqlite3_file *pConn){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL, 0);
if( pSubOpen && pSubOpen->pMethods->xSectorSize ){
return pSubOpen->pMethods->xSectorSize(pSubOpen);
}
@@ -960,7 +984,7 @@ static int multiplexSectorSize(sqlite3_file *pConn){
static int multiplexDeviceCharacteristics(sqlite3_file *pConn){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL, 0);
if( pSubOpen ){
return pSubOpen->pMethods->xDeviceCharacteristics(pSubOpen);
}
@@ -978,7 +1002,7 @@ static int multiplexShmMap(
){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL, 0);
if( pSubOpen ){
return pSubOpen->pMethods->xShmMap(pSubOpen, iRegion, szRegion, bExtend,pp);
}
@@ -995,7 +1019,7 @@ static int multiplexShmLock(
){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL, 0);
if( pSubOpen ){
return pSubOpen->pMethods->xShmLock(pSubOpen, ofst, n, flags);
}
@@ -1007,7 +1031,7 @@ static int multiplexShmLock(
static void multiplexShmBarrier(sqlite3_file *pConn){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL, 0);
if( pSubOpen ){
pSubOpen->pMethods->xShmBarrier(pSubOpen);
}
@@ -1018,7 +1042,7 @@ static void multiplexShmBarrier(sqlite3_file *pConn){
static int multiplexShmUnmap(sqlite3_file *pConn, int deleteFlag){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL, 0);
if( pSubOpen ){
return pSubOpen->pMethods->xShmUnmap(pSubOpen, deleteFlag);
}