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Overview
Comment:Experimental enhancement to automatically trim NULL values from the end of records, for a reduced disk footprint. This change also involves increasing the P5 operand from 8 to 16 bits.
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Timelines: family | ancestors | descendants | both | trim-nulls
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SHA1: 118ded403b95050b74ae2b03919c43d614094a32
User & Date: drh 2017-01-25 14:58:27
Context
2017-01-25
17:44
Fix a problem with the pre-update hook on this branch. check-in: 6fc4fbfa user: dan tags: trim-nulls
14:58
Experimental enhancement to automatically trim NULL values from the end of records, for a reduced disk footprint. This change also involves increasing the P5 operand from 8 to 16 bits. check-in: 118ded40 user: drh tags: trim-nulls
14:38
Ensure that sqlite3_blob_reopen() correctly handles short rows. Fix for ticket [e6e962d6b0f06f46e]. check-in: 8cd1a445 user: drh tags: trunk
Changes
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Changes to src/insert.c.

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    sqlite3VdbeGoto(v, ipkTop+1);
    sqlite3VdbeJumpHere(v, ipkBottom);
  }
  
  *pbMayReplace = seenReplace;
  VdbeModuleComment((v, "END: GenCnstCks(%d)", seenReplace));
}


















/*
** This routine generates code to finish the INSERT or UPDATE operation
** that was started by a prior call to sqlite3GenerateConstraintChecks.
** A consecutive range of registers starting at regNewData contains the
** rowid and the content to be inserted.
**
................................................................................
    }
    sqlite3VdbeChangeP5(v, pik_flags);
  }
  if( !HasRowid(pTab) ) return;
  regData = regNewData + 1;
  regRec = sqlite3GetTempReg(pParse);
  sqlite3VdbeAddOp3(v, OP_MakeRecord, regData, pTab->nCol, regRec);

  if( !bAffinityDone ){
    sqlite3TableAffinity(v, pTab, 0);
    sqlite3ExprCacheAffinityChange(pParse, regData, pTab->nCol);
  }
  if( pParse->nested ){
    pik_flags = 0;
  }else{







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    sqlite3VdbeGoto(v, ipkTop+1);
    sqlite3VdbeJumpHere(v, ipkBottom);
  }
  
  *pbMayReplace = seenReplace;
  VdbeModuleComment((v, "END: GenCnstCks(%d)", seenReplace));
}

/*
** Change the P5 operand on the last opcode (which should be an OP_MakeRecord)
** to be the number of columns in table pTab that must not be NULL-trimmed.
**
** Or if no columns of pTab may be NULL-trimmed, leave P5 at zero.
*/
void sqlite3SetMakeRecordP5(Vdbe *v, Table *pTab){
  u16 i;

  /* Records with omitted columns are only allowed for schema format
  ** version 2 and later (SQLite version 3.1.4, 2005-02-20). */
  if( pTab->pSchema->file_format<2 ) return;

  for(i=pTab->nCol; i>1 && pTab->aCol[i-1].pDflt==0; i--){}
  sqlite3VdbeChangeP5(v, i);
}

/*
** This routine generates code to finish the INSERT or UPDATE operation
** that was started by a prior call to sqlite3GenerateConstraintChecks.
** A consecutive range of registers starting at regNewData contains the
** rowid and the content to be inserted.
**
................................................................................
    }
    sqlite3VdbeChangeP5(v, pik_flags);
  }
  if( !HasRowid(pTab) ) return;
  regData = regNewData + 1;
  regRec = sqlite3GetTempReg(pParse);
  sqlite3VdbeAddOp3(v, OP_MakeRecord, regData, pTab->nCol, regRec);
  sqlite3SetMakeRecordP5(v, pTab);
  if( !bAffinityDone ){
    sqlite3TableAffinity(v, pTab, 0);
    sqlite3ExprCacheAffinityChange(pParse, regData, pTab->nCol);
  }
  if( pParse->nested ){
    pik_flags = 0;
  }else{

Changes to src/sqliteInt.h.

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void sqlite3GenerateRowDelete(
    Parse*,Table*,Trigger*,int,int,int,i16,u8,u8,u8,int);
void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int, int*, int);
int sqlite3GenerateIndexKey(Parse*, Index*, int, int, int, int*,Index*,int);
void sqlite3ResolvePartIdxLabel(Parse*,int);
void sqlite3GenerateConstraintChecks(Parse*,Table*,int*,int,int,int,int,
                                     u8,u8,int,int*,int*);

void sqlite3CompleteInsertion(Parse*,Table*,int,int,int,int*,int,int,int);
int sqlite3OpenTableAndIndices(Parse*, Table*, int, u8, int, u8*, int*, int*);
void sqlite3BeginWriteOperation(Parse*, int, int);
void sqlite3MultiWrite(Parse*);
void sqlite3MayAbort(Parse*);
void sqlite3HaltConstraint(Parse*, int, int, char*, i8, u8);
void sqlite3UniqueConstraint(Parse*, int, Index*);







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void sqlite3GenerateRowDelete(
    Parse*,Table*,Trigger*,int,int,int,i16,u8,u8,u8,int);
void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int, int*, int);
int sqlite3GenerateIndexKey(Parse*, Index*, int, int, int, int*,Index*,int);
void sqlite3ResolvePartIdxLabel(Parse*,int);
void sqlite3GenerateConstraintChecks(Parse*,Table*,int*,int,int,int,int,
                                     u8,u8,int,int*,int*);
void sqlite3SetMakeRecordP5(Vdbe*,Table*);
void sqlite3CompleteInsertion(Parse*,Table*,int,int,int,int*,int,int,int);
int sqlite3OpenTableAndIndices(Parse*, Table*, int, u8, int, u8*, int*, int*);
void sqlite3BeginWriteOperation(Parse*, int, int);
void sqlite3MultiWrite(Parse*);
void sqlite3MayAbort(Parse*);
void sqlite3HaltConstraint(Parse*, int, int, char*, i8, u8);
void sqlite3UniqueConstraint(Parse*, int, Index*);

Changes to src/vdbe.c.

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  if( zAffinity ){
    pRec = pData0;
    do{
      applyAffinity(pRec++, *(zAffinity++), encoding);
      assert( zAffinity[0]==0 || pRec<=pLast );
    }while( zAffinity[0] );
  }













  /* Loop through the elements that will make up the record to figure
  ** out how much space is required for the new record.
  */
  pRec = pLast;
  do{
    assert( memIsValid(pRec) );







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  if( zAffinity ){
    pRec = pData0;
    do{
      applyAffinity(pRec++, *(zAffinity++), encoding);
      assert( zAffinity[0]==0 || pRec<=pLast );
    }while( zAffinity[0] );
  }

  /* NULLs can be safely trimmed from the end of the record, as long as
  ** as the schema format is 2 or more and none of the omitted columns
  ** have a non-NULL default value.  Also, the record must be left with
  ** at least one field.  If P5>0 then it will be one more than the
  ** index of the right-most column with a non-NULL default value */
  if( pOp->p5 ){
    while( (pLast->flags & MEM_Null)!=0 && nField>pOp->p5 ){
      pLast--;
      nField--;
    }
  }

  /* Loop through the elements that will make up the record to figure
  ** out how much space is required for the new record.
  */
  pRec = pLast;
  do{
    assert( memIsValid(pRec) );

Changes to src/vdbe.h.

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** A single instruction of the virtual machine has an opcode
** and as many as three operands.  The instruction is recorded
** as an instance of the following structure:
*/
struct VdbeOp {
  u8 opcode;          /* What operation to perform */
  signed char p4type; /* One of the P4_xxx constants for p4 */
  u8 notUsed1;
  u8 p5;              /* Fifth parameter is an unsigned character */
  int p1;             /* First operand */
  int p2;             /* Second parameter (often the jump destination) */
  int p3;             /* The third parameter */
  union p4union {     /* fourth parameter */
    int i;                 /* Integer value if p4type==P4_INT32 */
    void *p;               /* Generic pointer */
    char *z;               /* Pointer to data for string (char array) types */
................................................................................
#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*, u8 P5);
void sqlite3VdbeJumpHere(Vdbe*, int addr);
int sqlite3VdbeChangeToNoop(Vdbe*, int addr);
int sqlite3VdbeDeletePriorOpcode(Vdbe*, u8 op);
void sqlite3VdbeChangeP4(Vdbe*, int addr, const char *zP4, int N);
void sqlite3VdbeAppendP4(Vdbe*, void *pP4, int p4type);
void sqlite3VdbeSetP4KeyInfo(Parse*, Index*);
void sqlite3VdbeUsesBtree(Vdbe*, int);







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** A single instruction of the virtual machine has an opcode
** and as many as three operands.  The instruction is recorded
** as an instance of the following structure:
*/
struct VdbeOp {
  u8 opcode;          /* What operation to perform */
  signed char p4type; /* One of the P4_xxx constants for p4 */

  u16 p5;             /* Fifth parameter is an unsigned 16-bit integer */
  int p1;             /* First operand */
  int p2;             /* Second parameter (often the jump destination) */
  int p3;             /* The third parameter */
  union p4union {     /* fourth parameter */
    int i;                 /* Integer value if p4type==P4_INT32 */
    void *p;               /* Generic pointer */
    char *z;               /* Pointer to data for string (char array) types */
................................................................................
#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);
void sqlite3VdbeChangeP4(Vdbe*, int addr, const char *zP4, int N);
void sqlite3VdbeAppendP4(Vdbe*, void *pP4, int p4type);
void sqlite3VdbeSetP4KeyInfo(Parse*, Index*);
void sqlite3VdbeUsesBtree(Vdbe*, int);

Changes to src/vdbeaux.c.

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}
void sqlite3VdbeChangeP2(Vdbe *p, u32 addr, int val){
  sqlite3VdbeGetOp(p,addr)->p2 = val;
}
void sqlite3VdbeChangeP3(Vdbe *p, u32 addr, int val){
  sqlite3VdbeGetOp(p,addr)->p3 = val;
}
void sqlite3VdbeChangeP5(Vdbe *p, u8 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.







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}
void sqlite3VdbeChangeP2(Vdbe *p, u32 addr, int val){
  sqlite3VdbeGetOp(p,addr)->p2 = val;
}
void sqlite3VdbeChangeP3(Vdbe *p, u32 addr, int val){
  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.