/ Check-in [699a77e4]
Login

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

Overview
Comment:Improvements to the EQP display for compound select statements.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | rework-EQP
Files: files | file ages | folders
SHA3-256:699a77e479010a331b0423f157a2fbfc373688e3d0d04ae5e64376c00cb3d488
User & Date: drh 2018-05-02 02:22:22
Context
2018-05-02
14:24
Fix a dangling-else problem that was causing recursive CTEs to malfunction. Begin fixing test cases to work with the new EQP output. check-in: 82ca44b8 user: drh tags: rework-EQP
02:22
Improvements to the EQP display for compound select statements. check-in: 699a77e4 user: drh tags: rework-EQP
00:33
Begin reengineering the EXPLAIN QUERY PLAN function to provide more intuitive output. check-in: 70b48a79 user: drh tags: rework-EQP
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/select.c.

1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
....
2511
2512
2513
2514
2515
2516
2517








2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
....
2539
2540
2541
2542
2543
2544
2545


2546
2547
2548
2549
2550
2551
2552
....
2607
2608
2609
2610
2611
2612
2613



2614
2615
2616
2617
2618
2619
2620
....
2683
2684
2685
2686
2687
2688
2689



2690
2691
2692
2693
2694
2695
2696
....
2714
2715
2716
2717
2718
2719
2720


2721


2722
2723
2724
2725
2726
2727
2728
....
3171
3172
3173
3174
3175
3176
3177
3178
3179

3180
3181
3182
3183
3184
3185
3186
3187


3188
3189
3190
3191
3192
3193
3194
....
3195
3196
3197
3198
3199
3200
3201


3202
3203
3204
3205
3206
3207
3208
....
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
....
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474

#else
/* No-op versions of the explainXXX() functions and macros. */
# define explainTempTable(y,z)
# define explainSetInteger(y,z)
#endif

#if !defined(SQLITE_OMIT_EXPLAIN) && !defined(SQLITE_OMIT_COMPOUND_SELECT)
/*
** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function
** is a no-op. Otherwise, it adds a single row of output to the EQP result,
** where the caption is of one of the two forms:
**
**   "COMPOSITE (op)"
**   "COMPOSITE USING TEMP B-TREE (op)"
**
** where op is the text representation of the parameter
** of the same name. The parameter "op" must be one of TK_UNION, TK_EXCEPT,
** TK_INTERSECT or TK_ALL. The first form is used if argument bUseTmp is 
** false, or the second form if it is true.
*/
static void explainComposite(
  Parse *pParse,                  /* Parse context */
  int op,                         /* One of TK_UNION, TK_EXCEPT etc. */
  int bUseTmp                     /* True if a temp table was used */
){
  assert( op==TK_UNION || op==TK_EXCEPT || op==TK_INTERSECT || op==TK_ALL );
  ExplainQueryPlan((pParse, 1, "COMPOUND %s(%s)",
        bUseTmp?"USING TEMP B-TREE ":"", selectOpName(op)));
}
#else
/* No-op versions of the explainXXX() functions and macros. */
# define explainComposite(v,y,z)
#endif

/*
** If the inner loop was generated using a non-null pOrderBy argument,
** then the results were placed in a sorter.  After the loop is terminated
** we need to run the sorter and output the results.  The following
** routine generates the code needed to do that.
*/
................................................................................
#endif

  /* Compound SELECTs that have an ORDER BY clause are handled separately.
  */
  if( p->pOrderBy ){
    return multiSelectOrderBy(pParse, p, pDest);
  }else









  /* Generate code for the left and right SELECT statements.
  */
  explainComposite(pParse, p->op, p->op!=TK_ALL);
  switch( p->op ){
    case TK_ALL: {
      int addr = 0;
      int nLimit;
      assert( !pPrior->pLimit );
      pPrior->iLimit = p->iLimit;
      pPrior->iOffset = p->iOffset;
................................................................................
        addr = sqlite3VdbeAddOp1(v, OP_IfNot, p->iLimit); VdbeCoverage(v);
        VdbeComment((v, "Jump ahead if LIMIT reached"));
        if( p->iOffset ){
          sqlite3VdbeAddOp3(v, OP_OffsetLimit,
                            p->iLimit, p->iOffset+1, p->iOffset);
        }
      }


      rc = sqlite3Select(pParse, p, &dest);
      testcase( rc!=SQLITE_OK );
      pDelete = p->pPrior;
      p->pPrior = pPrior;
      p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow);
      if( pPrior->pLimit
       && sqlite3ExprIsInteger(pPrior->pLimit->pLeft, &nLimit)
................................................................................
        assert( p->op==TK_UNION );
        op = SRT_Union;
      }
      p->pPrior = 0;
      pLimit = p->pLimit;
      p->pLimit = 0;
      uniondest.eDest = op;



      rc = sqlite3Select(pParse, p, &uniondest);
      testcase( rc!=SQLITE_OK );
      /* Query flattening in sqlite3Select() might refill p->pOrderBy.
      ** Be sure to delete p->pOrderBy, therefore, to avoid a memory leak. */
      sqlite3ExprListDelete(db, p->pOrderBy);
      pDelete = p->pPrior;
      p->pPrior = pPrior;
................................................................................
      addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab2, 0);
      assert( p->addrOpenEphm[1] == -1 );
      p->addrOpenEphm[1] = addr;
      p->pPrior = 0;
      pLimit = p->pLimit;
      p->pLimit = 0;
      intersectdest.iSDParm = tab2;



      rc = sqlite3Select(pParse, p, &intersectdest);
      testcase( rc!=SQLITE_OK );
      pDelete = p->pPrior;
      p->pPrior = pPrior;
      if( p->nSelectRow>pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow;
      sqlite3ExprDelete(db, p->pLimit);
      p->pLimit = pLimit;
................................................................................
      sqlite3VdbeResolveLabel(v, iBreak);
      sqlite3VdbeAddOp2(v, OP_Close, tab2, 0);
      sqlite3VdbeAddOp2(v, OP_Close, tab1, 0);
      break;
    }
  }



  ExplainQueryPlanPop(pParse);



  /* Compute collating sequences used by 
  ** temporary tables needed to implement the compound select.
  ** Attach the KeyInfo structure to all temporary tables.
  **
  ** This section is run by the right-most SELECT statement only.
  ** SELECT statements to the left always skip this part.  The right-most
................................................................................

  regAddrA = ++pParse->nMem;
  regAddrB = ++pParse->nMem;
  regOutA = ++pParse->nMem;
  regOutB = ++pParse->nMem;
  sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA);
  sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB);
  explainComposite(pParse, p->op, 0);



  /* Generate a coroutine to evaluate the SELECT statement to the
  ** left of the compound operator - the "A" select.
  */
  addrSelectA = sqlite3VdbeCurrentAddr(v) + 1;
  addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrA, 0, addrSelectA);
  VdbeComment((v, "left SELECT"));
  pPrior->iLimit = regLimitA;


  sqlite3Select(pParse, pPrior, &destA);
  sqlite3VdbeEndCoroutine(v, regAddrA);
  sqlite3VdbeJumpHere(v, addr1);

  /* Generate a coroutine to evaluate the SELECT statement on 
  ** the right - the "B" select
  */
................................................................................
  addrSelectB = sqlite3VdbeCurrentAddr(v) + 1;
  addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrB, 0, addrSelectB);
  VdbeComment((v, "right SELECT"));
  savedLimit = p->iLimit;
  savedOffset = p->iOffset;
  p->iLimit = regLimitB;
  p->iOffset = 0;  


  sqlite3Select(pParse, p, &destB);
  p->iLimit = savedLimit;
  p->iOffset = savedOffset;
  sqlite3VdbeEndCoroutine(v, regAddrB);

  /* Generate a subroutine that outputs the current row of the A
  ** select as the next output row of the compound select.
................................................................................
  db = pParse->db;
  v = sqlite3GetVdbe(pParse);
  if( p==0 || db->mallocFailed || pParse->nErr ){
    return 1;
  }
  if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;
  memset(&sAggInfo, 0, sizeof(sAggInfo));
#ifndef SQLITE_OMIT_EXPLAIN
  if( p->iSelectId==0 && pParse->addrExplain ){
    ExplainQueryPlan((pParse, 1, "SUBQUERY"));
    p->iSelectId = pParse->addrExplain;
  }
#endif
#if SELECTTRACE_ENABLED
  SELECTTRACE(1,pParse,p, ("begin processing:\n", pParse->addrExplain));
  if( sqlite3SelectTrace & 0x100 ){
    sqlite3TreeViewSelect(0, p, 0);
  }
#endif

................................................................................
    rc = multiSelect(pParse, p, pDest);
#if SELECTTRACE_ENABLED
    SELECTTRACE(0x1,pParse,p,("end compound-select processing\n"));
    if( (sqlite3SelectTrace & 0x2000)!=0 && ExplainQueryPlanParent(pParse)==0 ){
      sqlite3TreeViewSelect(0, p, 0);
    }
#endif
    sqlite3VdbeExplainPop(pParse);
    return rc;
  }
#endif

  /* For each term in the FROM clause, do two things:
  ** (1) Authorized unreferenced tables
  ** (2) Generate code for all sub-queries







<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<







 







>
>
>
>
>
>
>
>



<







 







>
>







 







>
>
>







 







>
>
>







 







>
>
|
>
>







 







<

>








>
>







 







>
>







 







<
<
<
<
<
<







 







|







1310
1311
1312
1313
1314
1315
1316



























1317
1318
1319
1320
1321
1322
1323
....
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501

2502
2503
2504
2505
2506
2507
2508
....
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
....
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
....
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
....
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
....
3163
3164
3165
3166
3167
3168
3169

3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
....
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
....
5314
5315
5316
5317
5318
5319
5320






5321
5322
5323
5324
5325
5326
5327
....
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464

#else
/* No-op versions of the explainXXX() functions and macros. */
# define explainTempTable(y,z)
# define explainSetInteger(y,z)
#endif





























/*
** If the inner loop was generated using a non-null pOrderBy argument,
** then the results were placed in a sorter.  After the loop is terminated
** we need to run the sorter and output the results.  The following
** routine generates the code needed to do that.
*/
................................................................................
#endif

  /* Compound SELECTs that have an ORDER BY clause are handled separately.
  */
  if( p->pOrderBy ){
    return multiSelectOrderBy(pParse, p, pDest);
  }else

#ifndef SQLITE_OMIT_EXPLAIN
  if( pPrior->pPrior==0 ){
    ExplainQueryPlan((pParse, 1, "COMPOUND QUERY"));
    ExplainQueryPlan((pParse, 1, "LEFT-MOST SUBQUERY"));
    ExplainQueryPlanSetId(pParse, pPrior);
  }
#endif

  /* Generate code for the left and right SELECT statements.
  */

  switch( p->op ){
    case TK_ALL: {
      int addr = 0;
      int nLimit;
      assert( !pPrior->pLimit );
      pPrior->iLimit = p->iLimit;
      pPrior->iOffset = p->iOffset;
................................................................................
        addr = sqlite3VdbeAddOp1(v, OP_IfNot, p->iLimit); VdbeCoverage(v);
        VdbeComment((v, "Jump ahead if LIMIT reached"));
        if( p->iOffset ){
          sqlite3VdbeAddOp3(v, OP_OffsetLimit,
                            p->iLimit, p->iOffset+1, p->iOffset);
        }
      }
      ExplainQueryPlan((pParse, 1, "UNION ALL"));
      ExplainQueryPlanSetId(pParse, p);
      rc = sqlite3Select(pParse, p, &dest);
      testcase( rc!=SQLITE_OK );
      pDelete = p->pPrior;
      p->pPrior = pPrior;
      p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow);
      if( pPrior->pLimit
       && sqlite3ExprIsInteger(pPrior->pLimit->pLeft, &nLimit)
................................................................................
        assert( p->op==TK_UNION );
        op = SRT_Union;
      }
      p->pPrior = 0;
      pLimit = p->pLimit;
      p->pLimit = 0;
      uniondest.eDest = op;
      ExplainQueryPlan((pParse, 1, "%s USING TEMP B-TREE",
                        selectOpName(p->op)));
      ExplainQueryPlanSetId(pParse, p);
      rc = sqlite3Select(pParse, p, &uniondest);
      testcase( rc!=SQLITE_OK );
      /* Query flattening in sqlite3Select() might refill p->pOrderBy.
      ** Be sure to delete p->pOrderBy, therefore, to avoid a memory leak. */
      sqlite3ExprListDelete(db, p->pOrderBy);
      pDelete = p->pPrior;
      p->pPrior = pPrior;
................................................................................
      addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab2, 0);
      assert( p->addrOpenEphm[1] == -1 );
      p->addrOpenEphm[1] = addr;
      p->pPrior = 0;
      pLimit = p->pLimit;
      p->pLimit = 0;
      intersectdest.iSDParm = tab2;
      ExplainQueryPlan((pParse, 1, "%s USING TEMP B-TREE",
                        selectOpName(p->op)));
      ExplainQueryPlanSetId(pParse, p);
      rc = sqlite3Select(pParse, p, &intersectdest);
      testcase( rc!=SQLITE_OK );
      pDelete = p->pPrior;
      p->pPrior = pPrior;
      if( p->nSelectRow>pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow;
      sqlite3ExprDelete(db, p->pLimit);
      p->pLimit = pLimit;
................................................................................
      sqlite3VdbeResolveLabel(v, iBreak);
      sqlite3VdbeAddOp2(v, OP_Close, tab2, 0);
      sqlite3VdbeAddOp2(v, OP_Close, tab1, 0);
      break;
    }
  }

#ifndef SQLITE_OMIT_EXPLAIN
  if( p->pNext==0 ){
    ExplainQueryPlanPop(pParse);
  }
#endif

  /* Compute collating sequences used by 
  ** temporary tables needed to implement the compound select.
  ** Attach the KeyInfo structure to all temporary tables.
  **
  ** This section is run by the right-most SELECT statement only.
  ** SELECT statements to the left always skip this part.  The right-most
................................................................................

  regAddrA = ++pParse->nMem;
  regAddrB = ++pParse->nMem;
  regOutA = ++pParse->nMem;
  regOutB = ++pParse->nMem;
  sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA);
  sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB);


  ExplainQueryPlan((pParse, 1, "MERGE (%s)", selectOpName(p->op)));

  /* Generate a coroutine to evaluate the SELECT statement to the
  ** left of the compound operator - the "A" select.
  */
  addrSelectA = sqlite3VdbeCurrentAddr(v) + 1;
  addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrA, 0, addrSelectA);
  VdbeComment((v, "left SELECT"));
  pPrior->iLimit = regLimitA;
  ExplainQueryPlan((pParse, 1, "LEFT"));
  ExplainQueryPlanSetId(pParse, pPrior);
  sqlite3Select(pParse, pPrior, &destA);
  sqlite3VdbeEndCoroutine(v, regAddrA);
  sqlite3VdbeJumpHere(v, addr1);

  /* Generate a coroutine to evaluate the SELECT statement on 
  ** the right - the "B" select
  */
................................................................................
  addrSelectB = sqlite3VdbeCurrentAddr(v) + 1;
  addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrB, 0, addrSelectB);
  VdbeComment((v, "right SELECT"));
  savedLimit = p->iLimit;
  savedOffset = p->iOffset;
  p->iLimit = regLimitB;
  p->iOffset = 0;  
  ExplainQueryPlan((pParse, 1, "RIGHT"));
  ExplainQueryPlanSetId(pParse, p);
  sqlite3Select(pParse, p, &destB);
  p->iLimit = savedLimit;
  p->iOffset = savedOffset;
  sqlite3VdbeEndCoroutine(v, regAddrB);

  /* Generate a subroutine that outputs the current row of the A
  ** select as the next output row of the compound select.
................................................................................
  db = pParse->db;
  v = sqlite3GetVdbe(pParse);
  if( p==0 || db->mallocFailed || pParse->nErr ){
    return 1;
  }
  if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;
  memset(&sAggInfo, 0, sizeof(sAggInfo));






#if SELECTTRACE_ENABLED
  SELECTTRACE(1,pParse,p, ("begin processing:\n", pParse->addrExplain));
  if( sqlite3SelectTrace & 0x100 ){
    sqlite3TreeViewSelect(0, p, 0);
  }
#endif

................................................................................
    rc = multiSelect(pParse, p, pDest);
#if SELECTTRACE_ENABLED
    SELECTTRACE(0x1,pParse,p,("end compound-select processing\n"));
    if( (sqlite3SelectTrace & 0x2000)!=0 && ExplainQueryPlanParent(pParse)==0 ){
      sqlite3TreeViewSelect(0, p, 0);
    }
#endif
    if( p->pNext==0 ) ExplainQueryPlanPop(pParse);
    return rc;
  }
#endif

  /* For each term in the FROM clause, do two things:
  ** (1) Authorized unreferenced tables
  ** (2) Generate code for all sub-queries