internal RC btreeDropTable(Pgno iTable, ref int piMoved)
{
MemPage pPage = null;
var pBt = this.Shared;
Debug.Assert(sqlite3BtreeHoldsMutex());
Debug.Assert(this.InTransaction == TRANS.WRITE);
// It is illegal to drop a table if any cursors are open on the database. This is because in auto-vacuum mode the backend may
// need to move another root-page to fill a gap left by the deleted root page. If an open cursor was using this page a problem would occur.
// This error is caught long before control reaches this point.
if (Check.NEVER(pBt.Cursors) != null)
{
sqlite3b.sqlite3ConnectionBlocked(this.DB, pBt.Cursors.Tree.DB);
return(RC.LOCKED_SHAREDCACHE);
}
var rc = pBt.btreeGetPage((Pgno)iTable, ref pPage, 0);
if (rc != RC.OK)
{
return(rc);
}
var dummy0 = 0;
rc = ClearTable((int)iTable, ref dummy0);
if (rc != RC.OK)
{
pPage.releasePage();
return(rc);
}
piMoved = 0;
if (iTable > 1)
{
#if SQLITE_OMIT_AUTOVACUUM
freePage(pPage, ref rc);
releasePage(pPage);
#else
if (pBt.AutoVacuum)
{
Pgno maxRootPgno = 0;
GetMeta((int)META.LARGEST_ROOT_PAGE, ref maxRootPgno);
if (iTable == maxRootPgno)
{
// If the table being dropped is the table with the largest root-page number in the database, put the root page on the free list.
pPage.freePage(ref rc);
pPage.releasePage();
if (rc != RC.OK)
{
return(rc);
}
}
else
{
// The table being dropped does not have the largest root-page number in the database. So move the page that does into the
// gap left by the deleted root-page.
var pMove = new MemPage();
pPage.releasePage();
rc = pBt.btreeGetPage(maxRootPgno, ref pMove, 0);
if (rc != RC.OK)
{
return(rc);
}
rc = MemPage.relocatePage(pBt, pMove, PTRMAP.ROOTPAGE, 0, iTable, 0);
pMove.releasePage();
if (rc != RC.OK)
{
return(rc);
}
pMove = null;
rc = pBt.btreeGetPage(maxRootPgno, ref pMove, 0);
pMove.freePage(ref rc);
pMove.releasePage();
if (rc != RC.OK)
{
return(rc);
}
piMoved = (int)maxRootPgno;
}
// Set the new 'max-root-page' value in the database header. This is the old value less one, less one more if that happens to
// be a root-page number, less one again if that is the PENDING_BYTE_PAGE.
maxRootPgno--;
while (maxRootPgno == MemPage.PENDING_BYTE_PAGE(pBt) || MemPage.PTRMAP_ISPAGE(pBt, maxRootPgno))
{
maxRootPgno--;
}
Debug.Assert(maxRootPgno != MemPage.PENDING_BYTE_PAGE(pBt));
rc = SetMeta(4, maxRootPgno);
}
else
{
pPage.freePage(ref rc);
pPage.releasePage();
}
#endif
}
else
{
// If sqlite3BtreeDropTable was called on page 1. This really never should happen except in a corrupt database.
pPage.zeroPage(PTF_INTKEY | PTF_LEAF);
pPage.releasePage();
}
return(rc);
}
internal RC btreeCreateTable(ref int piTable, CREATETABLE createTabFlags)
{
var pBt = this.Shared;
var pRoot = new MemPage();
Pgno pgnoRoot = 0;
int ptfFlags; // Page-type flage for the root page of new table
RC rc;
Debug.Assert(sqlite3BtreeHoldsMutex());
Debug.Assert(pBt.InTransaction == TRANS.WRITE);
Debug.Assert(!pBt.ReadOnly);
#if SQLITE_OMIT_AUTOVACUUM
rc = allocateBtreePage(pBt, ref pRoot, ref pgnoRoot, 1, 0);
if (rc != SQLITE.OK)
{
return(rc);
}
#else
if (pBt.AutoVacuum)
{
Pgno pgnoMove = 0; // Move a page here to make room for the root-page
var pPageMove = new MemPage(); // The page to move to.
// Creating a new table may probably require moving an existing database to make room for the new tables root page. In case this page turns
// out to be an overflow page, delete all overflow page-map caches held by open cursors.
invalidateAllOverflowCache(pBt);
// Read the value of meta[3] from the database to determine where the root page of the new table should go. meta[3] is the largest root-page
// created so far, so the new root-page is (meta[3]+1).
GetMeta((int)META.LARGEST_ROOT_PAGE, ref pgnoRoot);
pgnoRoot++;
// The new root-page may not be allocated on a pointer-map page, or the PENDING_BYTE page.
while (pgnoRoot == MemPage.PTRMAP_PAGENO(pBt, pgnoRoot) || pgnoRoot == MemPage.PENDING_BYTE_PAGE(pBt))
{
pgnoRoot++;
}
Debug.Assert(pgnoRoot >= 3);
// Allocate a page. The page that currently resides at pgnoRoot will be moved to the allocated page (unless the allocated page happens to reside at pgnoRoot).
rc = pBt.allocateBtreePage(ref pPageMove, ref pgnoMove, pgnoRoot, 1);
if (rc != RC.OK)
{
return(rc);
}
if (pgnoMove != pgnoRoot)
{
// pgnoRoot is the page that will be used for the root-page of the new table (assuming an error did not occur). But we were
// allocated pgnoMove. If required (i.e. if it was not allocated by extending the file), the current page at position pgnoMove
// is already journaled.
PTRMAP eType = 0;
Pgno iPtrPage = 0;
pPageMove.releasePage();
// Move the page currently at pgnoRoot to pgnoMove.
rc = pBt.btreeGetPage(pgnoRoot, ref pRoot, 0);
if (rc != RC.OK)
{
return(rc);
}
rc = pBt.ptrmapGet(pgnoRoot, ref eType, ref iPtrPage);
if (eType == PTRMAP.ROOTPAGE || eType == PTRMAP.FREEPAGE)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
}
if (rc != RC.OK)
{
pRoot.releasePage();
return(rc);
}
Debug.Assert(eType != PTRMAP.ROOTPAGE);
Debug.Assert(eType != PTRMAP.FREEPAGE);
rc = MemPage.relocatePage(pBt, pRoot, eType, iPtrPage, pgnoMove, 0);
pRoot.releasePage();
// Obtain the page at pgnoRoot
if (rc != RC.OK)
{
return(rc);
}
rc = pBt.btreeGetPage(pgnoRoot, ref pRoot, 0);
if (rc != RC.OK)
{
return(rc);
}
rc = Pager.Write(pRoot.DbPage);
if (rc != RC.OK)
{
pRoot.releasePage();
return(rc);
}
}
else
{
pRoot = pPageMove;
}
// Update the pointer-map and meta-data with the new root-page number.
pBt.ptrmapPut(pgnoRoot, PTRMAP.ROOTPAGE, 0, ref rc);
if (rc != RC.OK)
{
pRoot.releasePage();
return(rc);
}
// When the new root page was allocated, page 1 was made writable in order either to increase the database filesize, or to decrement the
// freelist count. Hence, the sqlite3BtreeUpdateMeta() call cannot fail.
Debug.Assert(Pager.IsPageWriteable(pBt.Page1.DbPage));
rc = SetMeta(4, pgnoRoot);
if (Check.NEVER(rc != RC.OK))
{
pRoot.releasePage();
return(rc);
}
}
else
{
rc = pBt.allocateBtreePage(ref pRoot, ref pgnoRoot, 1, 0);
if (rc != RC.OK)
{
return(rc);
}
}
#endif
Debug.Assert(Pager.IsPageWriteable(pRoot.DbPage));
ptfFlags = ((createTabFlags & CREATETABLE.INTKEY) != 0 ? PTF_INTKEY | PTF_LEAFDATA | PTF_LEAF : PTF_ZERODATA | PTF_LEAF);
pRoot.zeroPage(ptfFlags);
Pager.Unref(pRoot.DbPage);
Debug.Assert((pBt.OpenFlags & OPEN.SINGLE) == 0 || pgnoRoot == 2);
piTable = (int)pgnoRoot;
return(RC.OK);
}
