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Allow BEGIN CONCURRENT transactions to contain schema modifications. However, this causes them to conflict with all other transactions.

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FossilOrigin-Name: 2160ede1d12591275c3d82026be7775fd6c890435ab6ca83600029e96ca381a8
This commit is contained in:
dan
2020-07-16 20:57:35 +00:00
parent 9ee441a3a5
commit d05cc8f8b7
10 changed files with 181 additions and 1932 deletions
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15
src/wal.c
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@@ -3973,11 +3973,10 @@ static int walUpgradeReadlock(Wal *pWal){
*/
int sqlite3WalLockForCommit(
Wal *pWal,
PgHdr *pPage1,
PgHdr *pPg1,
Bitvec *pAllRead,
Pgno *piConflict
){
Pager *pPager = pPage1->pPager;
int rc = walWriteLock(pWal);
/* If the database has been modified since this transaction was started,
@@ -4004,7 +4003,13 @@ int sqlite3WalLockForCommit(
int iHash;
int nLoop = 1+(bWal2 && walidxGetFile(&head)!=walidxGetFile(&pWal->hdr));
int iLoop;
if( pPg1==0 ){
/* If pPg1==0, then the current transaction modified the database
** schema. This means it conflicts with all other transactions. */
*piConflict = 1;
rc = SQLITE_BUSY_SNAPSHOT;
}
assert( nLoop==1 || nLoop==2 );
for(iLoop=0; rc==SQLITE_OK && iLoop<nLoop; iLoop++){
@@ -4057,7 +4062,7 @@ int sqlite3WalLockForCommit(
/* Check that the schema cookie has not been modified. If
** it has not, the commit can proceed. */
u8 aNew[4];
u8 *aOld = &((u8*)pPage1->pData)[40];
u8 *aOld = &((u8*)pPg1->pData)[40];
int sz;
i64 iOff;
u32 iFrame = sLoc.iZero + i;
@@ -4075,7 +4080,7 @@ int sqlite3WalLockForCommit(
}else if( sqlite3BitvecTestNotNull(pAllRead, sLoc.aPgno[i]) ){
*piConflict = sLoc.aPgno[i];
rc = SQLITE_BUSY_SNAPSHOT;
}else if( (pPg = sqlite3PagerLookup(pPager, sLoc.aPgno[i])) ){
}else if( (pPg = sqlite3PagerLookup(pPg1->pPager, sLoc.aPgno[i])) ){
/* Page aPgno[i], which is present in the pager cache, has been
** modified since the current CONCURRENT transaction was
** started. However it was not read by the current