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Overview
Comment:The previous fix for ticket [d85fffd6ffe856092ed8da] in check-in [0a514e62ad1ebe5c12da8dae] did not completely address the probably in that it only worked for cases where the OP_SCopy that loaded the register was the last instruction in the sequence for the expression, which is not necessarily the case for expressions like CASE...END. This revision prevents the registered that will be recomputed from being cached in the first place.
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SHA3-256:9fd0faf517993587d2f54212638545fc85fbbc84a031bcfae8c1e5894825d83b
User & Date: drh 2018-04-26 18:34:26
Context
2018-04-27
15:17
Enhance the comments in the templatevtab.c implementation. check-in: 05f6278a user: drh tags: trunk
2018-04-26
18:34
The previous fix for ticket [d85fffd6ffe856092ed8da] in check-in [0a514e62ad1ebe5c12da8dae] did not completely address the probably in that it only worked for cases where the OP_SCopy that loaded the register was the last instruction in the sequence for the expression, which is not necessarily the case for expressions like CASE...END. This revision prevents the registered that will be recomputed from being cached in the first place. check-in: 9fd0faf5 user: drh tags: trunk
17:43
When processing an "ORDER BY ... LIMIT" that does not use an index, check whether or not a record may appear in the final result set before adding it to the temp b-tree used for sorting. check-in: 0fcfc36c user: dan tags: trunk
Changes
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Changes to src/update.c.

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  for(i=0; i<pTab->nCol; i++){
    if( i==pTab->iPKey ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regNew+i);
    }else{
      j = aXRef[i];
      if( j>=0 ){
        sqlite3ExprCode(pParse, pChanges->a[j].pExpr, regNew+i);
        if( tmask&TRIGGER_BEFORE ){
          /* Must preserve copied values even in case the original is
          ** reloaded in the After-BEFORE-trigger-reload-loop below.
          ** Ticket d85fffd6ffe856092ed8daefa811b1e399706b28 */
          sqlite3VdbeSwapOpcode(v, -1, OP_SCopy, OP_Copy);
        }
      }else if( 0==(tmask&TRIGGER_BEFORE) || i>31 || (newmask & MASKBIT32(i)) ){
        /* This branch loads the value of a column that will not be changed 
        ** into a register. This is done if there are no BEFORE triggers, or
        ** if there are one or more BEFORE triggers that use this value via
        ** a new.* reference in a trigger program.
        */
        testcase( i==31 );
        testcase( i==32 );
        sqlite3ExprCodeGetColumnToReg(pParse, pTab, i, iDataCur, regNew+i);






      }else{
        sqlite3VdbeAddOp2(v, OP_Null, 0, regNew+i);
      }
    }
  }

  /* Fire any BEFORE UPDATE triggers. This happens before constraints are







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  for(i=0; i<pTab->nCol; i++){
    if( i==pTab->iPKey ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regNew+i);
    }else{
      j = aXRef[i];
      if( j>=0 ){
        sqlite3ExprCode(pParse, pChanges->a[j].pExpr, regNew+i);






      }else if( 0==(tmask&TRIGGER_BEFORE) || i>31 || (newmask & MASKBIT32(i)) ){
        /* This branch loads the value of a column that will not be changed 
        ** into a register. This is done if there are no BEFORE triggers, or
        ** if there are one or more BEFORE triggers that use this value via
        ** a new.* reference in a trigger program.
        */
        testcase( i==31 );
        testcase( i==32 );
        sqlite3ExprCodeGetColumnToReg(pParse, pTab, i, iDataCur, regNew+i);
        if( tmask & TRIGGER_BEFORE ){
          /* This value will be recomputed in After-BEFORE-trigger-reload-loop
          ** below, so make sure that it is not cached and reused.
          ** Ticket d85fffd6ffe856092ed8daefa811b1e399706b28. */
          sqlite3ExprCacheRemove(pParse, regNew+i, 1);
        }
      }else{
        sqlite3VdbeAddOp2(v, OP_Null, 0, regNew+i);
      }
    }
  }

  /* Fire any BEFORE UPDATE triggers. This happens before constraints are

Changes to src/vdbe.h.

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#else
# define sqlite3VdbeVerifyNoMallocRequired(A,B)
# define sqlite3VdbeVerifyNoResultRow(A)
#endif
VdbeOp *sqlite3VdbeAddOpList(Vdbe*, int nOp, VdbeOpList const *aOp, int iLineno);
void sqlite3VdbeAddParseSchemaOp(Vdbe*,int,char*);
void sqlite3VdbeChangeOpcode(Vdbe*, u32 addr, u8);
void sqlite3VdbeSwapOpcode(Vdbe*, u32 addr, u8, u8);
void sqlite3VdbeChangeP1(Vdbe*, u32 addr, int P1);
void sqlite3VdbeChangeP2(Vdbe*, u32 addr, int P2);
void sqlite3VdbeChangeP3(Vdbe*, u32 addr, int P3);
void sqlite3VdbeChangeP5(Vdbe*, u16 P5);
void sqlite3VdbeJumpHere(Vdbe*, int addr);
int sqlite3VdbeChangeToNoop(Vdbe*, int addr);
int sqlite3VdbeDeletePriorOpcode(Vdbe*, u8 op);







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#else
# define sqlite3VdbeVerifyNoMallocRequired(A,B)
# define sqlite3VdbeVerifyNoResultRow(A)
#endif
VdbeOp *sqlite3VdbeAddOpList(Vdbe*, int nOp, VdbeOpList const *aOp, int iLineno);
void sqlite3VdbeAddParseSchemaOp(Vdbe*,int,char*);
void sqlite3VdbeChangeOpcode(Vdbe*, u32 addr, u8);

void sqlite3VdbeChangeP1(Vdbe*, u32 addr, int P1);
void sqlite3VdbeChangeP2(Vdbe*, u32 addr, int P2);
void sqlite3VdbeChangeP3(Vdbe*, u32 addr, int P3);
void sqlite3VdbeChangeP5(Vdbe*, u16 P5);
void sqlite3VdbeJumpHere(Vdbe*, int addr);
int sqlite3VdbeChangeToNoop(Vdbe*, int addr);
int sqlite3VdbeDeletePriorOpcode(Vdbe*, u8 op);

Changes to src/vdbeaux.c.

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  sqlite3VdbeGetOp(p,addr)->p3 = val;
}
void sqlite3VdbeChangeP5(Vdbe *p, u16 p5){
  assert( p->nOp>0 || p->db->mallocFailed );
  if( p->nOp>0 ) p->aOp[p->nOp-1].p5 = p5;
}

/* Change the opcode to iNew if it was previously iOld */
void sqlite3VdbeSwapOpcode(Vdbe *p, u32 addr, u8 iOld, u8 iNew){
  VdbeOp *pOp = sqlite3VdbeGetOp(p,addr);
  if( pOp->opcode==iOld ) pOp->opcode = iNew;
}

/*
** Change the P2 operand of instruction addr so that it points to
** the address of the next instruction to be coded.
*/
void sqlite3VdbeJumpHere(Vdbe *p, int addr){
  sqlite3VdbeChangeP2(p, addr, p->nOp);
}







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  sqlite3VdbeGetOp(p,addr)->p3 = val;
}
void sqlite3VdbeChangeP5(Vdbe *p, u16 p5){
  assert( p->nOp>0 || p->db->mallocFailed );
  if( p->nOp>0 ) p->aOp[p->nOp-1].p5 = p5;
}







/*
** Change the P2 operand of instruction addr so that it points to
** the address of the next instruction to be coded.
*/
void sqlite3VdbeJumpHere(Vdbe *p, int addr){
  sqlite3VdbeChangeP2(p, addr, p->nOp);
}

Changes to test/trigger1.test.

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#
do_execsql_test trigger1-19.0 {
  CREATE TABLE t19(a INT PRIMARY KEY, b, c)WITHOUT ROWID;
  INSERT INTO t19(a,b,c) VALUES(1,2,3);
  CREATE TRIGGER t19r3 BEFORE UPDATE ON t19 BEGIN SELECT new.b; END;
  UPDATE t19 SET c=b WHERE a=1;
  SELECT * FROM t19;






} {1 2 2}

finish_test







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#
do_execsql_test trigger1-19.0 {
  CREATE TABLE t19(a INT PRIMARY KEY, b, c)WITHOUT ROWID;
  INSERT INTO t19(a,b,c) VALUES(1,2,3);
  CREATE TRIGGER t19r3 BEFORE UPDATE ON t19 BEGIN SELECT new.b; END;
  UPDATE t19 SET c=b WHERE a=1;
  SELECT * FROM t19;
} {1 2 2}
do_execsql_test trigger1-19.1 {
  DELETE FROM t19;
  INSERT INTO t19(a,b,c) VALUES(1,2,3);
  UPDATE t19 SET c=CASE WHEN b=2 THEN b ELSE b+99 END WHERE a=1;
  SELECT * FROM t19;
} {1 2 2}

finish_test