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Overview
Comment: | Change to using packed-memory-arrays instead of b-trees when performing an offline merge-sort for CREATE INDEX. This makes it easier to control the number of disc seeks required when merging. |
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Timelines: | family | ancestors | descendants | both | experimental |
Files: | files | file ages | folders |
SHA1: |
a4770d079c1b236eb54751e75a44cccc |
User & Date: | dan 2011-08-04 12:14:04.747 |
Context
2011-08-04
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18:43 | Fix a comment in vdbesort.c. (check-in: db8518cab8 user: dan tags: experimental) | |
12:14 | Change to using packed-memory-arrays instead of b-trees when performing an offline merge-sort for CREATE INDEX. This makes it easier to control the number of disc seeks required when merging. (check-in: a4770d079c user: dan tags: experimental) | |
2011-08-02
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10:56 | Minor fixes to vdbesort.c code in preparation for a major rework. (check-in: 7f339c0e26 user: dan tags: experimental) | |
Changes
Changes to src/btree.c.
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7273 7274 7275 7276 7277 7278 7279 7280 7281 | */ zeroPage(pPage, PTF_INTKEY|PTF_LEAF ); releasePage(pPage); } return rc; } int sqlite3BtreeDropTable(Btree *p, int iTable, int *piMoved){ int rc; sqlite3BtreeEnter(p); | > > > > > > | > | 7273 7274 7275 7276 7277 7278 7279 7280 7281 7282 7283 7284 7285 7286 7287 7288 7289 7290 7291 7292 7293 7294 7295 7296 | */ zeroPage(pPage, PTF_INTKEY|PTF_LEAF ); releasePage(pPage); } return rc; } int sqlite3BtreeDropTable(Btree *p, int iTable, int *piMoved){ BtShared *pBt = p->pBt; int rc; sqlite3BtreeEnter(p); if( (pBt->openFlags&BTREE_SINGLE) ){ pBt->nPage = 0; sqlite3PagerTruncateImage(pBt->pPager, 1); rc = newDatabase(pBt); }else{ rc = btreeDropTable(p, iTable, piMoved); } sqlite3BtreeLeave(p); return rc; } /* ** This function may only be called if the b-tree connection already |
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8164 8165 8166 8167 8168 8169 8170 | } } } pBt->doNotUseWAL = 0; return rc; } | > > | 8171 8172 8173 8174 8175 8176 8177 8178 8179 | } } } pBt->doNotUseWAL = 0; return rc; } |
Changes to src/vdbe.c.
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3151 3152 3153 3154 3155 3156 3157 | static const int vfsFlags = SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE | SQLITE_OPEN_EXCLUSIVE | SQLITE_OPEN_DELETEONCLOSE | SQLITE_OPEN_TRANSIENT_DB; | | < | 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163 3164 3165 | static const int vfsFlags = SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE | SQLITE_OPEN_EXCLUSIVE | SQLITE_OPEN_DELETEONCLOSE | SQLITE_OPEN_TRANSIENT_DB; int btflags = BTREE_OMIT_JOURNAL | BTREE_SINGLE | pOp->p5; assert( pOp->p1>=0 ); pCx = allocateCursor(p, pOp->p1, pOp->p2, -1, 1); if( pCx==0 ) goto no_mem; pCx->nullRow = 1; rc = sqlite3BtreeOpen(db->pVfs, 0, db, &pCx->pBt, btflags, vfsFlags); if( rc==SQLITE_OK ){ |
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Changes to src/vdbesort.c.
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19 20 21 22 23 24 25 | #include "vdbeInt.h" typedef struct VdbeSorterIter VdbeSorterIter; /* ** The aIter[] and aTree[] arrays are used to iterate through the sorter ** contents after it has been populated. To iterate through the sorter | | > > > > > > | | | | | | 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 | #include "vdbeInt.h" typedef struct VdbeSorterIter VdbeSorterIter; /* ** The aIter[] and aTree[] arrays are used to iterate through the sorter ** contents after it has been populated. To iterate through the sorter ** contents, the contents of all packed-memory-arrays (PMAs) must be ** merged. This structure supports merging any number of arrays in a ** single pass with no redundant comparison operations. ** ** TODO: It may turn out that the optimum number of PMAs to merge in a ** single pass is 2. If this is the case, this data structure could be ** simplified. ** ** The first few elements of the aIter[] array contain pointers into ** each of the PMAs being merged. An aIter[] element either points to a ** valid key or else is at EOF. For the purposes of the paragraphs below, ** we assume that the array is actually N elements in size, where N is the ** smallest power of 2 greater to or equal to nRoot. The extra aIter[] ** elements are treated as if they are empty PMAs (always at EOF). ** ** The aTree[] array is N elements in size. The value of N is stored in ** the VdbeSorter.nTree variable. ** ** The final (N/2) elements of aTree[] contain the results of comparing ** pairs of iterator keys together. Element i contains the result of ** comparing aIter[2*i-N] and aIter[2*i-N+1]. Whichever key is smaller, the |
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80 81 82 83 84 85 86 | ** ** In other words, each time we advance to the next sorter element, log2(N) ** key comparison operations are required, where N is the number of segments ** being merged (rounded up to the next power of 2). */ struct VdbeSorter { int nWorking; /* Start a new b-tree after this many pages */ | < < < < > > > > > | | < < < | > > > | | | | | | | > | < | < | | < < | > | < < < | < < < < < < > | > > > | < < < | | < > | | | | > > > | < < | | < < | | > > > > > > > > | | > | > > | < < < < < < < < < < < | | | | | < | < < < | < < < < < < < | > > > | | < > > > | | < | | < > > > | < | | | 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 | ** ** In other words, each time we advance to the next sorter element, log2(N) ** key comparison operations are required, where N is the number of segments ** being merged (rounded up to the next power of 2). */ struct VdbeSorter { int nWorking; /* Start a new b-tree after this many pages */ int nAlloc; /* Allocated size of aIter[] and aTree[] */ int nTree; /* Used size of aTree/aIter (power of 2) */ VdbeSorterIter *aIter; /* Array of iterators to merge */ int *aTree; /* Current state of incremental merge */ i64 iWriteOff; /* Current write offset within file pTemp1 */ sqlite3_file *pTemp1; /* PMA file 1 */ i64 *aOffset; /* Array of PMA offsets for file 1 */ int nOffset; /* Size of aOffset[] array */ }; /* ** The following type is an iterator for a PMA. It caches the current key in ** variables nKey/aKey. If the iterator is at EOF, pFile==0. */ struct VdbeSorterIter { i64 iReadOff; /* Current read offset */ i64 iEof; /* 1 byte past EOF for this iterator */ sqlite3_file *pFile; /* File iterator is reading from */ int nAlloc; /* Bytes of space at aAlloc */ u8 *aAlloc; /* Allocated space */ int nKey; /* Number of bytes in key */ u8 *aKey; /* Pointer to current key */ }; /* Minimum allowable value for the VdbeSorter.nWorking variable */ #define SORTER_MIN_SEGMENT_SIZE 10 /* Maximum number of segments to merge in a single go */ #define SORTER_MAX_MERGE_COUNT 2 /* ** Append integer iOff to the VdbeSorter.aOffset[] array of the sorter object ** passed as the second argument. SQLITE_NOMEM is returned if an OOM error ** is encountered, or SQLITE_OK if no error occurs. ** ** TODO: The aOffset[] array may grow indefinitely. Fix this. */ static int vdbeSorterAppendOffset(sqlite3 *db, VdbeSorter *p, i64 iOff){ int *aNew; /* New VdbeSorter.aRoot[] array */ p->aOffset = sqlite3DbReallocOrFree( db, p->aOffset, (p->nOffset+1)*sizeof(i64) ); if( !p->aOffset ) return SQLITE_NOMEM; p->aOffset[p->nOffset++] = iOff; return SQLITE_OK; } /* ** Free all memory belonging to the VdbeSorterIter object passed as the second ** argument. All structure fields are set to zero before returning. */ static void vdbeSorterIterZero(sqlite3 *db, VdbeSorterIter *pIter){ sqlite3DbFree(db, pIter->aAlloc); memset(pIter, 0, sizeof(VdbeSorterIter)); } /* ** Advance iterator pIter to the next key in its PMA. */ static int vdbeSorterIterNext( sqlite3 *db, /* Database handle (for sqlite3DbMalloc() ) */ VdbeSorterIter *pIter /* Iterator to advance */ ){ int rc; int nRead; int nRec; int iOff; assert( pIter->nAlloc>5 ); nRead = pIter->iEof - pIter->iReadOff; if( nRead>5 ) nRead = 5; if( nRead<=0 ){ vdbeSorterIterZero(db, pIter); return SQLITE_OK; } rc = sqlite3OsRead(pIter->pFile, pIter->aAlloc, nRead, pIter->iReadOff); iOff = getVarint32(pIter->aAlloc, nRec); if( rc==SQLITE_OK && (iOff+nRec)>nRead ){ int nRead2; if( (iOff+nRec)>pIter->nAlloc ){ int nNew = pIter->nAlloc*2; while( (iOff+nRec)>nNew ) nNew = nNew*2; pIter->aAlloc = sqlite3DbReallocOrFree(db, pIter->aAlloc, nNew); if( !pIter->aAlloc ) return SQLITE_NOMEM; pIter->nAlloc = nNew; } nRead2 = iOff + nRec - nRead; rc = sqlite3OsRead( pIter->pFile, &pIter->aAlloc[nRead], nRead2, pIter->iReadOff+nRead ); } assert( nRec>0 || rc!=SQLITE_OK ); pIter->iReadOff += iOff+nRec; pIter->nKey = nRec; pIter->aKey = &pIter->aAlloc[iOff]; return rc; } /* ** Initialize iterator pIter to scan through the PMA stored in file pFile ** starting at offset iStart and ending at offset iEof-1. This function ** leaves the iterator pointing to the first key in the PMA (or EOF if the ** PMA is empty). */ static int vdbeSorterIterInit( sqlite3 *db, /* Database handle */ sqlite3_file *pFile, /* File that the PMA is stored in */ i64 iStart, /* Start offset in pFile */ i64 iEof, /* 1 byte past the end of the PMA in pFile */ VdbeSorterIter *pIter /* Iterator to populate */ ){ assert( iEof>iStart ); assert( pIter->aAlloc==0 ); pIter->pFile = pFile; pIter->iEof = iEof; pIter->iReadOff = iStart; pIter->nAlloc = 128; pIter->aAlloc = (u8 *)sqlite3DbMallocRaw(db, pIter->nAlloc); if( !pIter->aAlloc ) return SQLITE_NOMEM; return vdbeSorterIterNext(db, pIter); } /* ** This function is called to compare two iterator keys when merging ** multiple b-tree segments. Parameter iOut is the index of the aTree[] ** value to recalculate. */ |
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251 252 253 254 255 256 257 | i1 = pSorter->aTree[iOut*2]; i2 = pSorter->aTree[iOut*2+1]; } p1 = &pSorter->aIter[i1]; p2 = &pSorter->aIter[i2]; | | | | 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 | i1 = pSorter->aTree[iOut*2]; i2 = pSorter->aTree[iOut*2+1]; } p1 = &pSorter->aIter[i1]; p2 = &pSorter->aIter[i2]; if( p1->pFile==0 ){ iRes = i2; }else if( p2->pFile==0 ){ iRes = i1; }else{ char aSpace[150]; UnpackedRecord *r1; r1 = sqlite3VdbeRecordUnpack( pCsr->pKeyInfo, p1->nKey, p1->aKey, aSpace, sizeof(aSpace) |
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280 281 282 283 284 285 286 | return SQLITE_OK; } /* ** Initialize the temporary index cursor just opened as a sorter cursor. */ int sqlite3VdbeSorterInit(sqlite3 *db, VdbeCursor *pCsr){ | < < < < < < | < | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 | return SQLITE_OK; } /* ** Initialize the temporary index cursor just opened as a sorter cursor. */ int sqlite3VdbeSorterInit(sqlite3 *db, VdbeCursor *pCsr){ VdbeSorter *pSorter; /* Allocated sorter object */ /* Cursor must be a temp cursor and not open on an intkey table */ assert( pCsr->pKeyInfo && pCsr->pBt ); pSorter = sqlite3DbMallocZero(db, sizeof(VdbeSorter)); if( !pSorter ) return SQLITE_NOMEM; pCsr->pSorter = pSorter; return SQLITE_OK; } /* ** Free any cursor components allocated by sqlite3VdbeSorterXXX routines. */ void sqlite3VdbeSorterClose(sqlite3 *db, VdbeCursor *pCsr){ VdbeSorter *pSorter = pCsr->pSorter; if( pSorter ){ if( pSorter->aIter ){ int i; for(i=0; i<pSorter->nAlloc; i++){ vdbeSorterIterZero(db, &pSorter->aIter[i]); } sqlite3DbFree(db, pSorter->aIter); sqlite3DbFree(db, pSorter->aTree); } if( pSorter->pTemp1 ){ sqlite3OsCloseFree(pSorter->pTemp1); } sqlite3DbFree(db, pSorter->aOffset); sqlite3DbFree(db, pSorter); pCsr->pSorter = 0; } } /* ** Allocate space for a file-handle and open a temporary file. If successful, ** set *ppFile to point to the malloc'd file-handle and return SQLITE_OK. ** Otherwise, set *ppFile to 0 and return an SQLite error code. */ static int vdbeSorterOpenTempFile(sqlite3 *db, sqlite3_file **ppFile){ int dummy; return sqlite3OsOpenMalloc(db->pVfs, 0, ppFile, SQLITE_OPEN_TEMP_DB | SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE | SQLITE_OPEN_EXCLUSIVE | SQLITE_OPEN_DELETEONCLOSE, &dummy ); } /* ** Write the current contents of the b-tree to a PMA. Return SQLITE_OK ** if successful, or an SQLite error code otherwise. */ static int sorterBtreeToPma(sqlite3 *db, VdbeCursor *pCsr){ int rc = SQLITE_OK; /* Return code */ VdbeSorter *pSorter = pCsr->pSorter; i64 iWriteOff = pSorter->iWriteOff; int res = 0; void *aMalloc = 0; int nMalloc = 0; rc = sqlite3BtreeFirst(pCsr->pCursor, &res); if( rc!=SQLITE_OK || res ) return rc; /* If the first temporary PMA file has not been opened, open it now. */ if( pSorter->pTemp1==0 ){ rc = vdbeSorterOpenTempFile(db, &pSorter->pTemp1); assert( rc!=SQLITE_OK || pSorter->pTemp1 ); assert( pSorter->iWriteOff==0 ); assert( pSorter->nOffset==0 ); assert( pSorter->aOffset==0 ); } if( rc==SQLITE_OK ){ for( rc = vdbeSorterAppendOffset(db, pSorter, iWriteOff); rc==SQLITE_OK && res==0; rc = sqlite3BtreeNext(pCsr->pCursor, &res) ){ i64 nKey; /* Size of this key in bytes */ u8 aVarint[9]; /* Buffer containing varint(nKey) */ int nVar; /* Number of bytes in aVarint[] used */ (void)sqlite3BtreeKeySize(pCsr->pCursor, &nKey); nVar = sqlite3PutVarint(aVarint, nKey); /* Write the size of the record in bytes to the output file */ rc = sqlite3OsWrite(pSorter->pTemp1, aVarint, nVar, iWriteOff); iWriteOff += nVar; /* Make sure the aMalloc[] buffer is large enough for the record */ if( rc==SQLITE_OK && nKey>nMalloc ){ aMalloc = sqlite3DbReallocOrFree(db, aMalloc, nKey); if( !aMalloc ){ rc = SQLITE_NOMEM; } } /* Write the record itself to the output file */ if( rc==SQLITE_OK ){ rc = sqlite3BtreeKey(pCsr->pCursor, 0, nKey, aMalloc); if( rc==SQLITE_OK ){ rc = sqlite3OsWrite(pSorter->pTemp1, aMalloc, nKey, iWriteOff); iWriteOff += nKey; } } if( rc!=SQLITE_OK ) break; } pSorter->iWriteOff = iWriteOff; sqlite3DbFree(db, aMalloc); } return rc; } /* ** This function is called on a sorter cursor before each row is inserted. ** If the current b-tree being constructed is already considered "full", ** a new tree is started. */ int sqlite3VdbeSorterWrite(sqlite3 *db, VdbeCursor *pCsr){ |
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347 348 349 350 351 352 353 | pSorter->nWorking = SORTER_MIN_SEGMENT_SIZE; } } /* If the number of pages used by the current b-tree segment is greater ** than the size of the working set (VdbeSorter.nWorking), start a new ** segment b-tree. */ | | > > > > | | > > > > > > > > < | | 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 | pSorter->nWorking = SORTER_MIN_SEGMENT_SIZE; } } /* If the number of pages used by the current b-tree segment is greater ** than the size of the working set (VdbeSorter.nWorking), start a new ** segment b-tree. */ if( pSorter->nWorking && nPage>=pSorter->nWorking ){ BtCursor *p = pCsr->pCursor;/* Cursor structure to close and reopen */ int iRoot; /* Root page of new tree */ /* Copy the current contents of the b-tree into a PMA in sorted order. ** Close the currently open b-tree cursor. */ rc = sorterBtreeToPma(db, pCsr); sqlite3BtreeCloseCursor(p); if( rc==SQLITE_OK ){ rc = sqlite3BtreeDropTable(pCsr->pBt, 2, 0); #ifdef SQLITE_DEBUG sqlite3PagerPagecount(pPager, &nPage); assert( rc!=SQLITE_OK || nPage==1 ); #endif } if( rc==SQLITE_OK ){ rc = sqlite3BtreeCreateTable(pCsr->pBt, &iRoot, BTREE_BLOBKEY); } if( rc==SQLITE_OK ){ assert( iRoot==2 ); rc = sqlite3BtreeCursor(pCsr->pBt, iRoot, 1, pCsr->pKeyInfo, p); } } } return rc; } /* ** Extend the pSorter->aIter[] and pSorter->aTree[] arrays using DbRealloc(). ** Return SQLITE_OK if successful, or SQLITE_NOMEM otherwise. */ static int vdbeSorterGrowArrays(sqlite3* db, VdbeSorter *pSorter){ int *aTree; /* New aTree[] allocation */ VdbeSorterIter *aIter; /* New aIter[] allocation */ int nOld = pSorter->nAlloc; /* Current size of arrays */ int nNew = (nOld?nOld*2:4); /* Size of arrays after reallocation */ /* Realloc aTree[]. */ aTree = sqlite3DbRealloc(db, pSorter->aTree, sizeof(int)*nNew); if( !aTree ) return SQLITE_NOMEM; memset(&aTree[nOld], 0, (nNew-nOld) * sizeof(int)); pSorter->aTree = aTree; |
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406 407 408 409 410 411 412 413 414 415 | ){ Pager *pPager = sqlite3BtreePager(pCsr->pBt); VdbeSorter *pSorter = pCsr->pSorter; int rc = SQLITE_OK; int i; int nMaxRef = (pSorter->nWorking * 9/10); int N = 2; /* Initialize as many iterators as possible. */ for(i=iFirst; | > > | > > > > > > > | | > < < | > > > > > | > > > > | > > | > > > > | | > > > | < > > > | > < | | > > > | > > > > | | > > > > > | | | | 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 | ){ Pager *pPager = sqlite3BtreePager(pCsr->pBt); VdbeSorter *pSorter = pCsr->pSorter; int rc = SQLITE_OK; int i; int nMaxRef = (pSorter->nWorking * 9/10); int N = 2; assert( iFirst<pSorter->nOffset ); /* Initialize as many iterators as possible. */ for(i=iFirst; rc==SQLITE_OK && i<pSorter->nOffset && (i-iFirst)<SORTER_MAX_MERGE_COUNT; i++ ){ int iIter = i - iFirst; assert( iIter<=pSorter->nAlloc ); if( iIter==pSorter->nAlloc ){ rc = vdbeSorterGrowArrays(db, pSorter); } if( rc==SQLITE_OK ){ VdbeSorterIter *pIter = &pSorter->aIter[iIter]; i64 iStart = pSorter->aOffset[i]; i64 iEof; if( i==(pSorter->nOffset-1) ){ iEof = pSorter->iWriteOff; }else{ iEof = pSorter->aOffset[i+1]; } rc = vdbeSorterIterInit(db, pSorter->pTemp1, iStart, iEof, pIter); if( i>iFirst+1 ){ int nRef = (i-iFirst)*10; if( nRef>=nMaxRef ){ i++; break; } } } } *piNext = i; assert( i>iFirst ); while( (i-iFirst)>N ) N += N; pSorter->nTree = N; /* Populate the aTree[] array. */ for(i=N-1; rc==SQLITE_OK && i>0; i--){ rc = vdbeSorterDoCompare(pCsr, i); } return rc; } /* ** Once the sorter has been populated, this function is called to prepare ** for iterating through its contents in sorted order. */ int sqlite3VdbeSorterRewind(sqlite3 *db, VdbeCursor *pCsr, int *pbEof){ VdbeSorter *pSorter = pCsr->pSorter; int rc; /* Return code */ sqlite3_file *pTemp2 = 0; /* Second temp file to use */ i64 iWrite2 = 0; /* Write offset for pTemp2 */ assert( pSorter ); /* Write the current b-tree to a PMA. Close the b-tree cursor. */ rc = sorterBtreeToPma(db, pCsr); sqlite3BtreeCloseCursor(pCsr->pCursor); if( rc!=SQLITE_OK ) return rc; if( pSorter->nOffset==0 ){ *pbEof = 1; return SQLITE_OK; } while( rc==SQLITE_OK ){ int iRoot = 0; int iNext = 0; /* Index of next segment to open */ int iNew = 0; /* Index of new, merged, PMA */ do { /* This call configures iterators for merging. */ rc = vdbeSorterInitMerge(db, pCsr, iNext, &iNext); assert( iNext>0 ); assert( rc!=SQLITE_OK || pSorter->aIter[ pSorter->aTree[1] ].pFile ); if( rc==SQLITE_OK && (iRoot>0 || iNext<pSorter->nOffset) ){ int pgno; int bEof = 0; if( pTemp2==0 ){ rc = vdbeSorterOpenTempFile(db, &pTemp2); } if( rc==SQLITE_OK ){ pSorter->aOffset[iRoot] = iWrite2; } while( rc==SQLITE_OK && bEof==0 ){ int nByte; VdbeSorterIter *pIter = &pSorter->aIter[ pSorter->aTree[1] ]; assert( pIter->pFile ); nByte = pIter->nKey + sqlite3VarintLen(pIter->nKey); rc = sqlite3OsWrite(pTemp2, pIter->aAlloc, nByte, iWrite2); iWrite2 += nByte; if( rc==SQLITE_OK ){ rc = sqlite3VdbeSorterNext(db, pCsr, &bEof); } } iRoot++; } }while( rc==SQLITE_OK && iNext<pSorter->nOffset ); if( iRoot==0 ){ break; }else{ sqlite3_file *pTmp = pSorter->pTemp1; pSorter->nOffset = iRoot; pSorter->pTemp1 = pTemp2; pTemp2 = pTmp; pSorter->iWriteOff = iWrite2; iWrite2 = 0; } } if( pTemp2 ){ sqlite3OsCloseFree(pTemp2); } *pbEof = (pSorter->aIter[pSorter->aTree[1]].pFile==0); return rc; } /* ** Advance to the next element in the sorter. */ int sqlite3VdbeSorterNext(sqlite3 *db, VdbeCursor *pCsr, int *pbEof){ VdbeSorter *pSorter = pCsr->pSorter; int iPrev = pSorter->aTree[1]; /* Index of iterator to advance */ int i; /* Index of aTree[] to recalculate */ int rc; /* Return code */ rc = vdbeSorterIterNext(db, &pSorter->aIter[iPrev]); for(i=(pSorter->nTree+iPrev)/2; rc==SQLITE_OK && i>0; i=i/2){ rc = vdbeSorterDoCompare(pCsr, i); } *pbEof = (pSorter->aIter[pSorter->aTree[1]].pFile==0); return rc; } /* ** Copy the current sorter key into the memory cell pOut. */ int sqlite3VdbeSorterRowkey(sqlite3 *db, VdbeCursor *pCsr, Mem *pOut){ |
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