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Add SQLITE_IOCAP_ZERO_DAMAGE and enable it for both unix and windows. Use

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this device characteristic to reduce the required work in journaling.
A side effect is that this changes the default page exists back to 1024
even with the use of statvfs().

FossilOrigin-Name: a0be6ea464695fdf1eaf2b7cf0652778617814f2
This commit is contained in:
drh
2011-12-17 19:49:02 +00:00
parent 9c0e29371e
commit 8bbaa89d8d
9 changed files with 65 additions and 40 deletions
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50
src/wal.c
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@@ -425,6 +425,7 @@ struct Wal {
u8 readOnly; /* WAL_RDWR, WAL_RDONLY, or WAL_SHM_RDONLY */
u8 truncateOnCommit; /* True to truncate WAL file on commit */
u8 noSyncHeader; /* Avoid WAL header fsyncs if true */
u8 noPadding; /* No need to pad transactions to sector size */
WalIndexHdr hdr; /* Wal-index header for current transaction */
const char *zWalName; /* Name of WAL file */
u32 nCkpt; /* Checkpoint sequence counter in the wal-header */
@@ -1310,6 +1311,7 @@ int sqlite3WalOpen(
}else{
int iDC = sqlite3OsDeviceCharacteristics(pRet->pWalFd);
if( iDC & SQLITE_IOCAP_SEQUENTIAL ){ pRet->noSyncHeader = 1; }
if( iDC & SQLITE_IOCAP_ZERO_DAMAGE ){ pRet->noPadding = 1; }
*ppWal = pRet;
WALTRACE(("WAL%d: opened\n", pRet));
}
@@ -2780,34 +2782,36 @@ int sqlite3WalFrames(
/* Sync the log file if the 'isSync' flag was specified. */
if( isCommit && (sync_flags & WAL_SYNC_TRANSACTIONS)!=0 ){
i64 iSegment = sqlite3OsSectorSize(pWal->pWalFd);
i64 iOffset = walFrameOffset(iFrame+1, szPage);
assert( iSegment>0 );
iSegment = (((iOffset+iSegment-1)/iSegment) * iSegment);
while( iOffset<iSegment ){
void *pData;
if( !pWal->noPadding ){
i64 iSegment = sqlite3OsSectorSize(pWal->pWalFd);
i64 iOffset = walFrameOffset(iFrame+1, szPage);
assert( iSegment>0 );
iSegment = (((iOffset+iSegment-1)/iSegment) * iSegment);
while( iOffset<iSegment ){
void *pData;
#if defined(SQLITE_HAS_CODEC)
if( (pData = sqlite3PagerCodec(pLast))==0 ) return SQLITE_NOMEM;
if( (pData = sqlite3PagerCodec(pLast))==0 ) return SQLITE_NOMEM;
#else
pData = pLast->pData;
pData = pLast->pData;
#endif
walEncodeFrame(pWal, pLast->pgno, nTruncate, pData, aFrame);
/* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL */
rc = walWriteToLog(pWal, aFrame, sizeof(aFrame), iOffset);
if( rc!=SQLITE_OK ){
return rc;
walEncodeFrame(pWal, pLast->pgno, nTruncate, pData, aFrame);
/* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL */
rc = walWriteToLog(pWal, aFrame, sizeof(aFrame), iOffset);
if( rc!=SQLITE_OK ){
return rc;
}
iOffset += WAL_FRAME_HDRSIZE;
rc = walWriteToLog(pWal, pData, szPage, iOffset);
if( rc!=SQLITE_OK ){
return rc;
}
nLast++;
iOffset += szPage;
}
iOffset += WAL_FRAME_HDRSIZE;
rc = walWriteToLog(pWal, pData, szPage, iOffset);
if( rc!=SQLITE_OK ){
return rc;
}
nLast++;
iOffset += szPage;
}
rc = sqlite3OsSync(pWal->pWalFd, sync_flags & SQLITE_SYNC_MASK);
}