/ Check-in [8658574e]
Login

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:Avoid an excess register allocation in UPDATE, when possible. This improves speed (slightly) and reduces the code footprint.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA3-256: 8658574e3f435f03a87c04f398bd05078ebc53ecb4a477d3b24902d701d935c4
User & Date: drh 2019-05-08 19:06:59
Context
2019-05-08
19:32
Simplification to the logic underlying PRAGMA case_sensitive_like. check-in: ef0015fd user: drh tags: trunk
19:06
Avoid an excess register allocation in UPDATE, when possible. This improves speed (slightly) and reduces the code footprint. check-in: 8658574e user: drh tags: trunk
18:49
Add tests to improve code coverage of the RBU module. check-in: ecb56b75 user: dan tags: trunk
Changes
Hide Diffs Unified Diffs Show Whitespace Changes Patch

Changes to src/update.c.

151
152
153
154
155
156
157

158
159
160
161
162
163
164
...
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
...
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
...
389
390
391
392
393
394
395






396
397
398
399
400
401
402
403
...
519
520
521
522
523
524
525


526
527
528
529
530
531
532
  Table *pTab;           /* The table to be updated */
  int addrTop = 0;       /* VDBE instruction address of the start of the loop */
  WhereInfo *pWInfo;     /* Information about the WHERE clause */
  Vdbe *v;               /* The virtual database engine */
  Index *pIdx;           /* For looping over indices */
  Index *pPk;            /* The PRIMARY KEY index for WITHOUT ROWID tables */
  int nIdx;              /* Number of indices that need updating */

  int iBaseCur;          /* Base cursor number */
  int iDataCur;          /* Cursor for the canonical data btree */
  int iIdxCur;           /* Cursor for the first index */
  sqlite3 *db;           /* The database structure */
  int *aRegIdx = 0;      /* Registers for to each index and the main table */
  int *aXRef = 0;        /* aXRef[i] is the index in pChanges->a[] of the
                         ** an expression for the i-th column of the table.
................................................................................
  hasFK = sqlite3FkRequired(pParse, pTab, aXRef, chngKey);

  /* There is one entry in the aRegIdx[] array for each index on the table
  ** being updated.  Fill in aRegIdx[] with a register number that will hold
  ** the key for accessing each index.
  */
  if( onError==OE_Replace ) bReplace = 1;
  for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
    int reg;
    if( chngKey || hasFK>1 || pIdx==pPk
     || indexWhereClauseMightChange(pIdx,aXRef,chngRowid)
    ){
      reg = ++pParse->nMem;
      pParse->nMem += pIdx->nColumn;
    }else{
................................................................................
          if( onError==OE_Default && pIdx->onError==OE_Replace ){
            bReplace = 1;
          }
          break;
        }
      }
    }
    if( reg==0 ) aToOpen[j+1] = 0;
    aRegIdx[j] = reg;
  }
  aRegIdx[j] = ++pParse->nMem;  /* Register storing the table record */
  if( bReplace ){
    /* If REPLACE conflict resolution might be invoked, open cursors on all 
    ** indexes in case they are needed to delete records.  */
    memset(aToOpen, 1, nIdx+1);
  }

  /* Begin generating code. */
................................................................................
  v = sqlite3GetVdbe(pParse);
  if( v==0 ) goto update_cleanup;
  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
  sqlite3BeginWriteOperation(pParse, pTrigger || hasFK, iDb);

  /* Allocate required registers. */
  if( !IsVirtual(pTab) ){






    regRowSet = ++pParse->nMem;
    regOldRowid = regNewRowid = ++pParse->nMem;
    if( chngPk || pTrigger || hasFK ){
      regOld = pParse->nMem + 1;
      pParse->nMem += pTab->nCol;
    }
    if( chngKey || pTrigger || hasFK ){
      regNewRowid = ++pParse->nMem;
................................................................................

  if( HasRowid(pTab) ){
    /* Read the rowid of the current row of the WHERE scan. In ONEPASS_OFF
    ** mode, write the rowid into the FIFO. In either of the one-pass modes,
    ** leave it in register regOldRowid.  */
    sqlite3VdbeAddOp2(v, OP_Rowid, iDataCur, regOldRowid);
    if( eOnePass==ONEPASS_OFF ){


      sqlite3VdbeAddOp2(v, OP_RowSetAdd, regRowSet, regOldRowid);
    }
  }else{
    /* Read the PK of the current row into an array of registers. In
    ** ONEPASS_OFF mode, serialize the array into a record and store it in
    ** the ephemeral table. Or, in ONEPASS_SINGLE or MULTI mode, change
    ** the OP_OpenEphemeral instruction to a Noop (the ephemeral table 







>







 







|







 







|
|

|







 







>
>
>
>
>
>
|







 







>
>







151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
...
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
...
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
...
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
...
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
  Table *pTab;           /* The table to be updated */
  int addrTop = 0;       /* VDBE instruction address of the start of the loop */
  WhereInfo *pWInfo;     /* Information about the WHERE clause */
  Vdbe *v;               /* The virtual database engine */
  Index *pIdx;           /* For looping over indices */
  Index *pPk;            /* The PRIMARY KEY index for WITHOUT ROWID tables */
  int nIdx;              /* Number of indices that need updating */
  int nAllIdx;           /* Total number of indexes */
  int iBaseCur;          /* Base cursor number */
  int iDataCur;          /* Cursor for the canonical data btree */
  int iIdxCur;           /* Cursor for the first index */
  sqlite3 *db;           /* The database structure */
  int *aRegIdx = 0;      /* Registers for to each index and the main table */
  int *aXRef = 0;        /* aXRef[i] is the index in pChanges->a[] of the
                         ** an expression for the i-th column of the table.
................................................................................
  hasFK = sqlite3FkRequired(pParse, pTab, aXRef, chngKey);

  /* There is one entry in the aRegIdx[] array for each index on the table
  ** being updated.  Fill in aRegIdx[] with a register number that will hold
  ** the key for accessing each index.
  */
  if( onError==OE_Replace ) bReplace = 1;
  for(nAllIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nAllIdx++){
    int reg;
    if( chngKey || hasFK>1 || pIdx==pPk
     || indexWhereClauseMightChange(pIdx,aXRef,chngRowid)
    ){
      reg = ++pParse->nMem;
      pParse->nMem += pIdx->nColumn;
    }else{
................................................................................
          if( onError==OE_Default && pIdx->onError==OE_Replace ){
            bReplace = 1;
          }
          break;
        }
      }
    }
    if( reg==0 ) aToOpen[nAllIdx+1] = 0;
    aRegIdx[nAllIdx] = reg;
  }
  aRegIdx[nAllIdx] = ++pParse->nMem;  /* Register storing the table record */
  if( bReplace ){
    /* If REPLACE conflict resolution might be invoked, open cursors on all 
    ** indexes in case they are needed to delete records.  */
    memset(aToOpen, 1, nIdx+1);
  }

  /* Begin generating code. */
................................................................................
  v = sqlite3GetVdbe(pParse);
  if( v==0 ) goto update_cleanup;
  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
  sqlite3BeginWriteOperation(pParse, pTrigger || hasFK, iDb);

  /* Allocate required registers. */
  if( !IsVirtual(pTab) ){
    /* For now, regRowSet and aRegIdx[nAllIdx] share the same register.
    ** If regRowSet turns out to be needed, then aRegIdx[nAllIdx] will be
    ** reallocated.  aRegIdx[nAllIdx] is the register in which the main
    ** table record is written.  regRowSet holds the RowSet for the
    ** two-pass update algorithm. */
    assert( aRegIdx[nAllIdx]==pParse->nMem );
    regRowSet = aRegIdx[nAllIdx];
    regOldRowid = regNewRowid = ++pParse->nMem;
    if( chngPk || pTrigger || hasFK ){
      regOld = pParse->nMem + 1;
      pParse->nMem += pTab->nCol;
    }
    if( chngKey || pTrigger || hasFK ){
      regNewRowid = ++pParse->nMem;
................................................................................

  if( HasRowid(pTab) ){
    /* Read the rowid of the current row of the WHERE scan. In ONEPASS_OFF
    ** mode, write the rowid into the FIFO. In either of the one-pass modes,
    ** leave it in register regOldRowid.  */
    sqlite3VdbeAddOp2(v, OP_Rowid, iDataCur, regOldRowid);
    if( eOnePass==ONEPASS_OFF ){
      /* We need to use regRowSet, so reallocate aRegIdx[nAllIdx] */
      aRegIdx[nAllIdx] = ++pParse->nMem;
      sqlite3VdbeAddOp2(v, OP_RowSetAdd, regRowSet, regOldRowid);
    }
  }else{
    /* Read the PK of the current row into an array of registers. In
    ** ONEPASS_OFF mode, serialize the array into a record and store it in
    ** the ephemeral table. Or, in ONEPASS_SINGLE or MULTI mode, change
    ** the OP_OpenEphemeral instruction to a Noop (the ephemeral table