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Overview
Comment:Improvements to opcode documentation in the bytecode engine. No changes to code.
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SHA3-256: e54c9f8db5b2fa8ea82c6eab7482255431af16901f7992c9667b56a0e50a9f4f
User & Date: drh 2017-04-29 18:02:49
Context
2017-04-29
19:29
Add a single testcase() macro to the subquery processing logic. check-in: 4e1df76e user: drh tags: trunk
18:02
Improvements to opcode documentation in the bytecode engine. No changes to code. check-in: e54c9f8d user: drh tags: trunk
15:27
Evaluate WHERE clause terms that reference only the index before evaluating terms that require the table, and thereby avoid seeking the table row if index terms are false. This is called the "push-down" optimization in the MySQL world, we are told. check-in: d7bb79ed user: drh tags: trunk
Changes
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Changes to src/vdbe.c.

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** to the current line should be indented for EXPLAIN output.
*/
case OP_Goto: {             /* jump */
jump_to_p2_and_check_for_interrupt:
  pOp = &aOp[pOp->p2 - 1];

  /* Opcodes that are used as the bottom of a loop (OP_Next, OP_Prev,
  ** OP_VNext, OP_RowSetNext, or OP_SorterNext) all jump here upon
  ** completion.  Check to see if sqlite3_interrupt() has been called
  ** or if the progress callback needs to be invoked. 
  **
  ** This code uses unstructured "goto" statements and does not look clean.
  ** But that is not due to sloppy coding habits. The code is written this
  ** way for performance, to avoid having to run the interrupt and progress
  ** checks on every opcode.  This helps sqlite3_step() to run about 1.5%
................................................................................
arithmetic_result_is_null:
  sqlite3VdbeMemSetNull(pOut);
  break;
}

/* Opcode: CollSeq P1 * * P4
**
** P4 is a pointer to a CollSeq struct. If the next call to a user function
** or aggregate calls sqlite3GetFuncCollSeq(), this collation sequence will
** be returned. This is used by the built-in min(), max() and nullif()
** functions.
**
** If P1 is not zero, then it is a register that a subsequent min() or
** max() aggregate will set to 1 if the current row is not the minimum or
** maximum.  The P1 register is initialized to 0 by this instruction.
................................................................................
#ifndef SQLITE_OMIT_CAST
/* Opcode: Cast P1 P2 * * *
** Synopsis: affinity(r[P1])
**
** Force the value in register P1 to be the type defined by P2.
** 
** <ul>
** <li value="97"> TEXT
** <li value="98"> BLOB
** <li value="99"> NUMERIC
** <li value="100"> INTEGER
** <li value="101"> REAL
** </ul>
**
** A NULL value is not changed by this routine.  It remains NULL.
*/
case OP_Cast: {                  /* in1 */
  assert( pOp->p2>=SQLITE_AFF_BLOB && pOp->p2<=SQLITE_AFF_REAL );
  testcase( pOp->p2==SQLITE_AFF_TEXT );
................................................................................
}

/* Opcode: Affinity P1 P2 * P4 *
** Synopsis: affinity(r[P1@P2])
**
** Apply affinities to a range of P2 registers starting with P1.
**
** P4 is a string that is P2 characters long. The nth character of the
** string indicates the column affinity that should be used for the nth
** memory cell in the range.
*/
case OP_Affinity: {
  const char *zAffinity;   /* The affinity to be applied */

  zAffinity = pOp->p4.z;
  assert( zAffinity!=0 );
................................................................................
/* Opcode: MakeRecord P1 P2 P3 P4 *
** Synopsis: r[P3]=mkrec(r[P1@P2])
**
** Convert P2 registers beginning with P1 into the [record format]
** use as a data record in a database table or as a key
** in an index.  The OP_Column opcode can decode the record later.
**
** P4 may be a string that is P2 characters long.  The nth character of the
** string indicates the column affinity that should be used for the nth
** field of the index key.
**
** The mapping from character to affinity is given by the SQLITE_AFF_
** macros defined in sqliteInt.h.
**
** If P4 is NULL then all index fields have the affinity BLOB.
*/
................................................................................
  break;
}
#endif /* SQLITE_OMIT_INTEGRITY_CHECK */

/* Opcode: RowSetAdd P1 P2 * * *
** Synopsis: rowset(P1)=r[P2]
**
** Insert the integer value held by register P2 into a boolean index
** held in register P1.
**
** An assertion fails if P2 is not an integer.
*/
case OP_RowSetAdd: {       /* in1, in2 */
  pIn1 = &aMem[pOp->p1];
  pIn2 = &aMem[pOp->p2];
................................................................................
  sqlite3RowSetInsert(pIn1->u.pRowSet, pIn2->u.i);
  break;
}

/* Opcode: RowSetRead P1 P2 P3 * *
** Synopsis: r[P3]=rowset(P1)
**
** Extract the smallest value from boolean index P1 and put that value into

** register P3.  Or, if boolean index P1 is initially empty, leave P3
** unchanged and jump to instruction P2.
*/
case OP_RowSetRead: {       /* jump, in1, out3 */
  i64 val;

  pIn1 = &aMem[pOp->p1];
  if( (pIn1->flags & MEM_RowSet)==0 
................................................................................
**
** Register P3 is assumed to hold a 64-bit integer value. If register P1
** contains a RowSet object and that RowSet object contains
** the value held in P3, jump to register P2. Otherwise, insert the
** integer in P3 into the RowSet and continue on to the
** next opcode.
**
** The RowSet object is optimized for the case where successive sets
** of integers, where each set contains no duplicates. Each set
** of values is identified by a unique P4 value. The first set
** must have P4==0, the final set P4=-1.  P4 must be either -1 or
** non-negative.  For non-negative values of P4 only the lower 4
** bits are significant.
**
** This allows optimizations: (a) when P4==0 there is no need to test
** the rowset object for P3, as it is guaranteed not to contain it,
** (b) when P4==-1 there is no need to insert the value, as it will
** never be tested for, and (c) when a value that is part of set X is
** inserted, there is no need to search to see if the same value was
** previously inserted as part of set X (only if it was previously
** inserted as part of some other set).
*/
case OP_RowSetTest: {                     /* jump, in1, in3 */







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** to the current line should be indented for EXPLAIN output.
*/
case OP_Goto: {             /* jump */
jump_to_p2_and_check_for_interrupt:
  pOp = &aOp[pOp->p2 - 1];

  /* Opcodes that are used as the bottom of a loop (OP_Next, OP_Prev,
  ** OP_VNext, or OP_SorterNext) all jump here upon
  ** completion.  Check to see if sqlite3_interrupt() has been called
  ** or if the progress callback needs to be invoked. 
  **
  ** This code uses unstructured "goto" statements and does not look clean.
  ** But that is not due to sloppy coding habits. The code is written this
  ** way for performance, to avoid having to run the interrupt and progress
  ** checks on every opcode.  This helps sqlite3_step() to run about 1.5%
................................................................................
arithmetic_result_is_null:
  sqlite3VdbeMemSetNull(pOut);
  break;
}

/* Opcode: CollSeq P1 * * P4
**
** P4 is a pointer to a CollSeq object. If the next call to a user function
** or aggregate calls sqlite3GetFuncCollSeq(), this collation sequence will
** be returned. This is used by the built-in min(), max() and nullif()
** functions.
**
** If P1 is not zero, then it is a register that a subsequent min() or
** max() aggregate will set to 1 if the current row is not the minimum or
** maximum.  The P1 register is initialized to 0 by this instruction.
................................................................................
#ifndef SQLITE_OMIT_CAST
/* Opcode: Cast P1 P2 * * *
** Synopsis: affinity(r[P1])
**
** Force the value in register P1 to be the type defined by P2.
** 
** <ul>
** <li> P2=='A' &rarr; BLOB
** <li> P2=='B' &rarr; TEXT
** <li> P2=='C' &rarr; NUMERIC
** <li> P2=='D' &rarr; INTEGER
** <li> P2=='E' &rarr; REAL
** </ul>
**
** A NULL value is not changed by this routine.  It remains NULL.
*/
case OP_Cast: {                  /* in1 */
  assert( pOp->p2>=SQLITE_AFF_BLOB && pOp->p2<=SQLITE_AFF_REAL );
  testcase( pOp->p2==SQLITE_AFF_TEXT );
................................................................................
}

/* Opcode: Affinity P1 P2 * P4 *
** Synopsis: affinity(r[P1@P2])
**
** Apply affinities to a range of P2 registers starting with P1.
**
** P4 is a string that is P2 characters long. The N-th character of the
** string indicates the column affinity that should be used for the N-th
** memory cell in the range.
*/
case OP_Affinity: {
  const char *zAffinity;   /* The affinity to be applied */

  zAffinity = pOp->p4.z;
  assert( zAffinity!=0 );
................................................................................
/* Opcode: MakeRecord P1 P2 P3 P4 *
** Synopsis: r[P3]=mkrec(r[P1@P2])
**
** Convert P2 registers beginning with P1 into the [record format]
** use as a data record in a database table or as a key
** in an index.  The OP_Column opcode can decode the record later.
**
** P4 may be a string that is P2 characters long.  The N-th character of the
** string indicates the column affinity that should be used for the N-th
** field of the index key.
**
** The mapping from character to affinity is given by the SQLITE_AFF_
** macros defined in sqliteInt.h.
**
** If P4 is NULL then all index fields have the affinity BLOB.
*/
................................................................................
  break;
}
#endif /* SQLITE_OMIT_INTEGRITY_CHECK */

/* Opcode: RowSetAdd P1 P2 * * *
** Synopsis: rowset(P1)=r[P2]
**
** Insert the integer value held by register P2 into a RowSet object
** held in register P1.
**
** An assertion fails if P2 is not an integer.
*/
case OP_RowSetAdd: {       /* in1, in2 */
  pIn1 = &aMem[pOp->p1];
  pIn2 = &aMem[pOp->p2];
................................................................................
  sqlite3RowSetInsert(pIn1->u.pRowSet, pIn2->u.i);
  break;
}

/* Opcode: RowSetRead P1 P2 P3 * *
** Synopsis: r[P3]=rowset(P1)
**
** Extract the smallest value from the RowSet object in P1
** and put that value into register P3.
** Or, if RowSet object P1 is initially empty, leave P3
** unchanged and jump to instruction P2.
*/
case OP_RowSetRead: {       /* jump, in1, out3 */
  i64 val;

  pIn1 = &aMem[pOp->p1];
  if( (pIn1->flags & MEM_RowSet)==0 
................................................................................
**
** Register P3 is assumed to hold a 64-bit integer value. If register P1
** contains a RowSet object and that RowSet object contains
** the value held in P3, jump to register P2. Otherwise, insert the
** integer in P3 into the RowSet and continue on to the
** next opcode.
**
** The RowSet object is optimized for the case where sets of integers
** are inserted in distinct phases, which each set contains no duplicates.
** Each set is identified by a unique P4 value. The first set
** must have P4==0, the final set must have P4==-1, and for all other sets
** must have P4>0.

**
** This allows optimizations: (a) when P4==0 there is no need to test
** the RowSet object for P3, as it is guaranteed not to contain it,
** (b) when P4==-1 there is no need to insert the value, as it will
** never be tested for, and (c) when a value that is part of set X is
** inserted, there is no need to search to see if the same value was
** previously inserted as part of set X (only if it was previously
** inserted as part of some other set).
*/
case OP_RowSetTest: {                     /* jump, in1, in3 */