database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2025-08-08 14:02:16 +03:00
Code Activity

Add the sqlite3_vtab_nochange() method which virtual table implementations

Browse Source 
can use to optimize UPDATEs.

FossilOrigin-Name: d444b1ff39f0a1673a977b8047e1e14a49d461c9934be080d27c2392a830c1c0
This commit is contained in:
drh
2018-01-11 17:04:26 +00:00
parent e4185bda9a
commit 6f390beb7f
7 changed files with 58 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
src/vdbe.c
View File

@@ -6693,12 +6693,18 @@ case OP_VFilter: { /* jump */
#endif /* SQLITE_OMIT_VIRTUALTABLE */
#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VColumn P1 P2 P3 * *
/* Opcode: VColumn P1 P2 P3 P4 *
** Synopsis: r[P3]=vcolumn(P2)
**
** Store the value of the P2-th column of
** the row of the virtual-table that the
** P1 cursor is pointing to into register P3.
** 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
** 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.
*/
case OP_VColumn: {
sqlite3_vtab *pVtab;
@@ -6720,6 +6726,7 @@ case OP_VColumn: {
assert( pModule->xColumn );
memset(&sContext, 0, sizeof(sContext));
sContext.pOut = pDest;
sContext.bVtabNoChng = pOp->p4.i!=0;
MemSetTypeFlag(pDest, MEM_Null);
rc = pModule->xColumn(pCur->uc.pVCur, &sContext, pOp->p2);
sqlite3VtabImportErrmsg(p, pVtab);