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Overview
Comment: | In temp files used for merge sorting, store the size of each packed-memory-array at the start of the array itself. This is to avoid having to store the offsets of all arrays in the (potentially very large) file in main-memory. |
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Timelines: | family | ancestors | descendants | both | experimental |
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SHA1: |
8051c1767c4386b0f14a66742d9fac41 |
User & Date: | dan 2011-08-06 12:01:58.831 |
Context
2011-08-06
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15:09 | Fix a problem with building large indexes introduced by the previous commit. (check-in: 038ec9ea92 user: dan tags: experimental) | |
12:01 | In temp files used for merge sorting, store the size of each packed-memory-array at the start of the array itself. This is to avoid having to store the offsets of all arrays in the (potentially very large) file in main-memory. (check-in: 8051c1767c user: dan tags: experimental) | |
2011-08-05
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11:49 | Minor internal changes to vdbesort.c. Also, default to merging lists together 16 at a time. (check-in: 9ddc324a34 user: dan tags: experimental) | |
Changes
Changes to src/vdbe.c.
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4369 4370 4371 4372 4373 4374 4375 | BtCursor *pCrsr; int nKey; const char *zKey; assert( pOp->p1>=0 && pOp->p1<p->nCursor ); pC = p->apCsr[pOp->p1]; assert( pC!=0 ); | < < > > > | 4369 4370 4371 4372 4373 4374 4375 4376 4377 4378 4379 4380 4381 4382 4383 4384 4385 4386 4387 4388 4389 4390 4391 4392 4393 4394 4395 4396 4397 4398 | BtCursor *pCrsr; int nKey; const char *zKey; assert( pOp->p1>=0 && pOp->p1<p->nCursor ); pC = p->apCsr[pOp->p1]; assert( pC!=0 ); pIn2 = &aMem[pOp->p2]; assert( pIn2->flags & MEM_Blob ); pCrsr = pC->pCursor; if( ALWAYS(pCrsr!=0) ){ assert( pC->isTable==0 ); rc = ExpandBlob(pIn2); if( rc==SQLITE_OK ){ nKey = pIn2->n; zKey = pIn2->z; rc = sqlite3VdbeSorterWrite(db, pC, nKey); if( rc==SQLITE_OK ){ rc = sqlite3BtreeInsert(pCrsr, zKey, nKey, "", 0, 0, pOp->p3, ((pOp->p5 & OPFLAG_USESEEKRESULT) ? pC->seekResult : 0) ); assert( pC->deferredMoveto==0 ); } pC->cacheStatus = CACHE_STALE; } } break; } /* Opcode: IdxDelete P1 P2 P3 * * |
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Changes to src/vdbeInt.h.
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389 390 391 392 393 394 395 | int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve); int sqlite3VdbeCloseStatement(Vdbe *, int); void sqlite3VdbeFrameDelete(VdbeFrame*); int sqlite3VdbeFrameRestore(VdbeFrame *); void sqlite3VdbeMemStoreType(Mem *pMem); int sqlite3VdbeSorterInit(sqlite3 *, VdbeCursor *); | | | 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 | int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve); int sqlite3VdbeCloseStatement(Vdbe *, int); void sqlite3VdbeFrameDelete(VdbeFrame*); int sqlite3VdbeFrameRestore(VdbeFrame *); void sqlite3VdbeMemStoreType(Mem *pMem); int sqlite3VdbeSorterInit(sqlite3 *, VdbeCursor *); int sqlite3VdbeSorterWrite(sqlite3 *, VdbeCursor *, int); void sqlite3VdbeSorterClose(sqlite3 *, VdbeCursor *); int sqlite3VdbeSorterRowkey(sqlite3 *, VdbeCursor *, Mem *); int sqlite3VdbeSorterRewind(sqlite3 *, VdbeCursor *, int *); int sqlite3VdbeSorterNext(sqlite3 *, VdbeCursor *, int *); #if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0 |
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Changes to src/vdbesort.c.
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85 86 87 88 89 90 91 92 93 94 | ** ** 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 nTree; /* Used size of aTree/aIter (power of 2) */ VdbeSorterIter *aIter; /* Array of iterators to merge */ int *aTree; /* Current state of incremental merge */ | > < > < | | < < < < < < < < < < < < < < < < | 85 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 | ** ** 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 nBtree; /* Current size of b-tree contents as PMA */ 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 */ i64 iReadOff; /* Current read offset within file pTemp1 */ sqlite3_file *pTemp1; /* PMA file 1 */ int nPMA; /* Number of PMAs stored in pTemp1 */ }; /* ** 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 pass. */ #define SORTER_MAX_MERGE_COUNT 16 /* ** 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)); |
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152 153 154 155 156 157 158 | VdbeSorterIter *pIter /* Iterator to advance */ ){ int rc; int nRead; int nRec; int iOff; | < < | 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 | VdbeSorterIter *pIter /* Iterator to advance */ ){ int rc; int nRead; int nRec; int iOff; 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); |
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187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 | 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 */ | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | < | > > > > | < | > > > > > > > > | > > | 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 | assert( nRec>0 || rc!=SQLITE_OK ); pIter->iReadOff += iOff+nRec; pIter->nKey = nRec; pIter->aKey = &pIter->aAlloc[iOff]; return rc; } static int vdbeSorterWriteVarint( sqlite3_file *pFile, i64 iVal, i64 *piOffset ){ u8 aVarint[9]; /* Buffer large enough for a varint */ int nVarint; /* Number of used bytes in varint */ int rc; /* Result of write() call */ nVarint = sqlite3PutVarint(aVarint, iVal); rc = sqlite3OsWrite(pFile, aVarint, nVarint, *piOffset); *piOffset += nVarint; return rc; } static int vdbeSorterReadVarint( sqlite3_file *pFile, i64 iEof, /* Total number of bytes in file */ i64 *piOffset, /* IN/OUT: Read offset */ i64 *piVal /* OUT: Value read from file */ ){ u8 aVarint[9]; /* Buffer large enough for a varint */ i64 iOff = *piOffset; /* Offset in file to read from */ int nRead = 9; /* Number of bytes to read from file */ int rc; /* Return code */ assert( iEof>iOff ); if( (iEof-iOff)<nRead ){ nRead = iEof-iOff; } rc = sqlite3OsRead(pFile, aVarint, nRead, iOff); if( rc==SQLITE_OK ){ *piOffset += getVarint(aVarint, (u64 *)piVal); } 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 */ VdbeSorter *pSorter, /* Sorter object */ i64 iStart, /* Start offset in pFile */ VdbeSorterIter *pIter, /* Iterator to populate */ i64 *pnByte /* IN/OUT: Increment this value by PMA size */ ){ int rc; i64 iEof = pSorter->iWriteOff; assert( iEof>iStart ); assert( pIter->aAlloc==0 ); pIter->pFile = pSorter->pTemp1; pIter->iReadOff = iStart; pIter->nAlloc = 128; pIter->aAlloc = (u8 *)sqlite3DbMallocRaw(db, pIter->nAlloc); if( !pIter->aAlloc ){ rc = SQLITE_NOMEM; }else{ i64 nByte; rc = vdbeSorterReadVarint(pSorter->pTemp1, iEof, &pIter->iReadOff, &nByte); *pnByte += nByte; pIter->iEof = pIter->iReadOff + nByte; } if( rc==SQLITE_OK ){ rc = vdbeSorterIterNext(db, pIter); } return rc; } /* ** 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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294 295 296 297 298 299 300 | vdbeSorterIterZero(db, &pSorter->aIter[i]); } sqlite3DbFree(db, pSorter->aIter); } if( pSorter->pTemp1 ){ sqlite3OsCloseFree(pSorter->pTemp1); } | < > | | < > > > > > | < < < < < | | < > > > > | | 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 | vdbeSorterIterZero(db, &pSorter->aIter[i]); } sqlite3DbFree(db, pSorter->aIter); } if( pSorter->pTemp1 ){ sqlite3OsCloseFree(pSorter->pTemp1); } 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 vdbeSorterBtreeToPMA(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->nPMA==0 ); } if( rc==SQLITE_OK ){ pSorter->nPMA++; /* Write a varint containg the size of the PMA in bytes into the file. */ assert( pSorter->nBtree>0 ); for( rc = vdbeSorterWriteVarint(pSorter->pTemp1, pSorter->nBtree, &iWriteOff); rc==SQLITE_OK && res==0; rc = sqlite3BtreeNext(pCsr->pCursor, &res) ){ i64 nKey; /* Size of this key in bytes */ /* Write the size of the record in bytes to the output file */ (void)sqlite3BtreeKeySize(pCsr->pCursor, &nKey); rc = vdbeSorterWriteVarint(pSorter->pTemp1, nKey, &iWriteOff); /* 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; } } } assert( pSorter->nBtree==( iWriteOff-pSorter->iWriteOff-sqlite3VarintLen(pSorter->nBtree) )); pSorter->iWriteOff = iWriteOff; sqlite3DbFree(db, aMalloc); } pSorter->nBtree = 0; 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, int nKey){ int rc = SQLITE_OK; /* Return code */ VdbeSorter *pSorter = pCsr->pSorter; if( pSorter ){ Pager *pPager = sqlite3BtreePager(pCsr->pBt); int nPage; /* Current size of temporary file in pages */ sqlite3PagerPagecount(pPager, &nPage); |
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419 420 421 422 423 424 425 | ** 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. */ | | > > | < < | < < < < < < < < < < < < < < | < < < | < < < < < < < | < < | | < | > > > > | | > > > > | > > > > > | > < > > > > > > > > | > > | < > > | < < > > > | > > < < | | > | > < > < | 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 | ** 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 = vdbeSorterBtreeToPMA(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); } } pSorter->nBtree += sqlite3VarintLen(nKey) + nKey; } return rc; } /* ** Helper function for sqlite3VdbeSorterRewind(). */ static int vdbeSorterInitMerge( sqlite3 *db, VdbeCursor *pCsr, int iFirst, i64 *pnByte /* Sum of bytes in all opened PMAs */ ){ VdbeSorter *pSorter = pCsr->pSorter; int rc = SQLITE_OK; int i; i64 nByte = 0; /* Initialize as many iterators as possible. */ for(i=iFirst; rc==SQLITE_OK && i<pSorter->nPMA && (i-iFirst)<SORTER_MAX_MERGE_COUNT; i++ ){ VdbeSorterIter *pIter = &pSorter->aIter[i - iFirst]; rc = vdbeSorterIterInit(db, pSorter, pSorter->iReadOff, pIter, &nByte); pSorter->iReadOff = pIter->iEof; } assert( i>iFirst ); /* Populate the aTree[] array. */ for(i=pSorter->nTree-1; rc==SQLITE_OK && i>0; i--){ rc = vdbeSorterDoCompare(pCsr, i); } *pnByte = nByte; 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 */ int nIter; /* Number of iterators used */ int nByte; /* Bytes of space required for aIter/aTree */ int N = 2; /* Power of 2 >= nIter */ assert( pSorter ); /* Write the current b-tree to a PMA. Close the b-tree cursor. */ rc = vdbeSorterBtreeToPMA(db, pCsr); sqlite3BtreeCloseCursor(pCsr->pCursor); if( rc!=SQLITE_OK ) return rc; if( pSorter->nPMA==0 ){ *pbEof = 1; return SQLITE_OK; } /* Allocate space for aIter[] and aTree[]. */ nIter = pSorter->nPMA; if( nIter>SORTER_MAX_MERGE_COUNT ) nIter = SORTER_MAX_MERGE_COUNT; assert( nIter>0 ); while( N<nIter ) N += N; nByte = N * (sizeof(int) + sizeof(VdbeSorterIter)); pSorter->aIter = (VdbeSorterIter *)sqlite3DbMallocZero(db, nByte); if( !pSorter->aIter ) return SQLITE_NOMEM; pSorter->aTree = (int *)&pSorter->aIter[N]; pSorter->nTree = N; do { int iNew = 0; /* Index of new, merged, PMA */ for(iNew=0; rc==SQLITE_OK; iNew++){ i64 nWrite; /* Number of bytes in new PMA */ /* If there are SORTER_MAX_MERGE_COUNT or less PMAs in file pTemp1, ** initialize an iterator for each of them and break out of the loop. ** These iterators will be incrementally merged as the VDBE layer calls ** sqlite3VdbeSorterNext(). ** ** Otherwise, if pTemp1 contains more than SORTER_MAX_MERGE_COUNT PMAs, ** initialize interators for SORTER_MAX_MERGE_COUNT of them. These PMAs ** are merged into a single PMA that is written to file pTemp2. */ rc = vdbeSorterInitMerge(db, pCsr, iNew*SORTER_MAX_MERGE_COUNT, &nWrite); assert( rc!=SQLITE_OK || pSorter->aIter[ pSorter->aTree[1] ].pFile ); if( rc!=SQLITE_OK || pSorter->nPMA<=SORTER_MAX_MERGE_COUNT ){ break; } /* Open the second temp file, if it is not already open. */ if( pTemp2==0 ){ assert( iWrite2==0 ); rc = vdbeSorterOpenTempFile(db, &pTemp2); } if( rc==SQLITE_OK ){ rc = vdbeSorterWriteVarint(pTemp2, nWrite, &iWrite2); } if( rc==SQLITE_OK ){ int bEof = 0; 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); } } } } if( pSorter->nPMA<=SORTER_MAX_MERGE_COUNT ){ break; }else{ sqlite3_file *pTmp = pSorter->pTemp1; pSorter->nPMA = iNew; pSorter->pTemp1 = pTemp2; pTemp2 = pTmp; pSorter->iWriteOff = iWrite2; pSorter->iReadOff = 0; iWrite2 = 0; } }while( rc==SQLITE_OK ); if( pTemp2 ){ sqlite3OsCloseFree(pTemp2); } *pbEof = (pSorter->aIter[pSorter->aTree[1]].pFile==0); return rc; } /* ** Advance to the next element in the sorter. */ |
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