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Overview
Comment:Very small performance enhancement and reduction in size of the sqlite3_stmt object.
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SHA1: a38d57a4e5d79a0baefdf776e0e2d61423681a4f
User & Date: drh 2012-02-01 19:03:38
Context
2012-02-02
01:58
Remove the nAlloc field from the ExprList object. check-in: 5963de30 user: drh tags: trunk
2012-02-01
19:03
Very small performance enhancement and reduction in size of the sqlite3_stmt object. check-in: a38d57a4 user: drh tags: trunk
01:13
Fix ALTER TABLE RENAME so that it correctly handles triggers that attach to the table using the name in a different case. Ticket [ae6794effd404]. check-in: 0d78ebb8 user: drh tags: trunk
Changes
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Changes to src/vdbeInt.h.

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  Mem **apArg;            /* Arguments to currently executing user function */
  Mem *aColName;          /* Column names to return */
  Mem *pResultSet;        /* Pointer to an array of results */
  int nMem;               /* Number of memory locations currently allocated */
  int nOp;                /* Number of instructions in the program */
  int nOpAlloc;           /* Number of slots allocated for aOp[] */
  int nLabel;             /* Number of labels used */
  int nLabelAlloc;        /* Number of slots allocated in aLabel[] */
  int *aLabel;            /* Space to hold the labels */
  u16 nResColumn;         /* Number of columns in one row of the result set */
  u16 nCursor;            /* Number of slots in apCsr[] */
  u32 magic;              /* Magic number for sanity checking */
  char *zErrMsg;          /* Error message written here */
  Vdbe *pPrev,*pNext;     /* Linked list of VDBEs with the same Vdbe.db */
  VdbeCursor **apCsr;     /* One element of this array for each open cursor */







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  Mem **apArg;            /* Arguments to currently executing user function */
  Mem *aColName;          /* Column names to return */
  Mem *pResultSet;        /* Pointer to an array of results */
  int nMem;               /* Number of memory locations currently allocated */
  int nOp;                /* Number of instructions in the program */
  int nOpAlloc;           /* Number of slots allocated for aOp[] */
  int nLabel;             /* Number of labels used */

  int *aLabel;            /* Space to hold the labels */
  u16 nResColumn;         /* Number of columns in one row of the result set */
  u16 nCursor;            /* Number of slots in apCsr[] */
  u32 magic;              /* Magic number for sanity checking */
  char *zErrMsg;          /* Error message written here */
  Vdbe *pPrev,*pNext;     /* Linked list of VDBEs with the same Vdbe.db */
  VdbeCursor **apCsr;     /* One element of this array for each open cursor */

Changes to src/vdbeaux.c.

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** The VDBE knows that a P2 value is a label because labels are
** always negative and P2 values are suppose to be non-negative.
** Hence, a negative P2 value is a label that has yet to be resolved.
**
** Zero is returned if a malloc() fails.
*/
int sqlite3VdbeMakeLabel(Vdbe *p){
  int i;
  i = p->nLabel++;
  assert( p->magic==VDBE_MAGIC_INIT );
  if( i>=p->nLabelAlloc ){
    int n = p->nLabelAlloc*2 + 5;

    p->aLabel = sqlite3DbReallocOrFree(p->db, p->aLabel,
                                       n*sizeof(p->aLabel[0]));
    p->nLabelAlloc = sqlite3DbMallocSize(p->db, p->aLabel)/sizeof(p->aLabel[0]);
  }
  if( p->aLabel ){
    p->aLabel[i] = -1;
  }
  return -1-i;
}








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** The VDBE knows that a P2 value is a label because labels are
** always negative and P2 values are suppose to be non-negative.
** Hence, a negative P2 value is a label that has yet to be resolved.
**
** Zero is returned if a malloc() fails.
*/
int sqlite3VdbeMakeLabel(Vdbe *p){

  int i = p->nLabel++;
  assert( p->magic==VDBE_MAGIC_INIT );


  if( (i & (i-1))==0 ){
    p->aLabel = sqlite3DbReallocOrFree(p->db, p->aLabel, 
                                       (i*2+1)*sizeof(p->aLabel[0]));

  }
  if( p->aLabel ){
    p->aLabel[i] = -1;
  }
  return -1-i;
}