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Add the experimental sqlite3_value_nochange() interface usable by xUpdate

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methods of virtual tables to see if a column has actually changed values.

FossilOrigin-Name: 8b7be15ece9e2e83959bb0e21e240106fe1077431242c3cc6b81f1baa2382f40
This commit is contained in:
drh
2018-01-12 21:00:14 +00:00
parent 4ec6f3a075
commit ce2fbd1b02
9 changed files with 56 additions and 24 deletions
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23
src/vdbe.c
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@@ -464,7 +464,7 @@ static void memTracePrint(Mem *p){
if( p->flags & MEM_Undefined ){
printf(" undefined");
}else if( p->flags & MEM_Null ){
printf(" NULL");
printf(p->flags & MEM_Zero ? " NULL-nochng" : " NULL");
}else if( (p->flags & (MEM_Int|MEM_Str))==(MEM_Int|MEM_Str) ){
printf(" si:%lld", p->u.i);
}else if( p->flags & MEM_Int ){
@@ -2794,7 +2794,11 @@ case OP_MakeRecord: {
assert( memIsValid(pRec) );
pRec->uTemp = serial_type = sqlite3VdbeSerialType(pRec, file_format, &len);
if( pRec->flags & MEM_Zero ){
if( nData ){
if( serial_type==0 ){
assert( pOp->p5==2 || CORRUPT_DB );
/* serial_type 10 used internally only */
pRec->uTemp = 10;
}else if( nData ){
if( sqlite3VdbeMemExpandBlob(pRec) ) goto no_mem;
}else{
nZero += pRec->u.nZero;
@@ -6697,15 +6701,15 @@ case OP_VFilter: { /* jump */
#endif /* SQLITE_OMIT_VIRTUALTABLE */
#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VColumn P1 P2 P3 P4 *
/* Opcode: VColumn P1 P2 P3 * P5
** Synopsis: r[P3]=vcolumn(P2)
**
** Store in register P3 the value of the P2-th column of
** the current row of the virtual-table of cursor P1.
**
** If the VColumn opcode is being used to fetch the value of
** an unchanging column during an UPDATE operation, then the P4
** value is 1. Otherwise, P4 is 0. The P4 value is returned
** an unchanging column during an UPDATE operation, then the P5
** value is 1. Otherwise, P5 is 0. The P5 value is returned
** by sqlite3_vtab_nochange() routine can can be used
** by virtual table implementations to return special "no-change"
** marks which can be more efficient, depending on the virtual table.
@@ -6730,8 +6734,13 @@ case OP_VColumn: {
assert( pModule->xColumn );
memset(&sContext, 0, sizeof(sContext));
sContext.pOut = pDest;
sContext.bVtabNoChng = pOp->p4.i!=0;
MemSetTypeFlag(pDest, MEM_Null);
if( pOp->p5 ){
sqlite3VdbeMemSetNull(pDest);
pDest->flags = MEM_Null|MEM_Zero;
pDest->u.nZero = 0;
}else{
MemSetTypeFlag(pDest, MEM_Null);
}
rc = pModule->xColumn(pCur->uc.pVCur, &sContext, pOp->p2);
sqlite3VtabImportErrmsg(p, pVtab);
if( sContext.isError ){