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Overview
| Comment: | Extra VDBE comments in the NULLS LAST logic provide landmarks to help understand the EXPLAIN output. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | nulls-last |
| Files: | files | file ages | folders |
| SHA3-256: |
649b08ead50f10a9ec0357a5e1ed0201 |
| User & Date: | drh 2019-08-23 13:08:49 |
Context
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2019-08-23
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| 13:32 | Invert the meaning of the regBignull flag so that it is 1 when doing the normal scan and 1 when scanning nulls. This enables the re-do jump at the bottom of the loop to be coded with a single OP_IfNotZero opcode, rather than a sequence of OP_If, OP_Integer, OP_Goto. (check-in: bf875e1a user: drh tags: nulls-last) | |
| 13:08 | Extra VDBE comments in the NULLS LAST logic provide landmarks to help understand the EXPLAIN output. (check-in: 649b08ea user: drh tags: nulls-last) | |
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2019-08-22
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| 21:13 | Add additional VDBE coverage macros. (check-in: d3531f5b user: drh tags: nulls-last) | |
Changes
Changes to src/where.c.
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VdbeCoverage(v);
VdbeCoverageIf(v, pLevel->op==OP_Next);
VdbeCoverageIf(v, pLevel->op==OP_Prev);
VdbeCoverageIf(v, pLevel->op==OP_VNext);
if( pLevel->regBignull ){
sqlite3VdbeResolveLabel(v, pLevel->addrBignull);
addr = sqlite3VdbeAddOp1(v, OP_If, pLevel->regBignull);
VdbeCoverage(v);
sqlite3VdbeAddOp2(v, OP_Integer, 1, pLevel->regBignull);
sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->p2-1);
sqlite3VdbeJumpHere(v, addr);
}
#ifndef SQLITE_DISABLE_SKIPAHEAD_DISTINCT
if( addrSeek ) sqlite3VdbeJumpHere(v, addrSeek);
#endif
}else{
sqlite3VdbeResolveLabel(v, pLevel->addrCont);
|
> > |
5215 5216 5217 5218 5219 5220 5221 5222 5223 5224 5225 5226 5227 5228 5229 5230 5231 5232 5233 |
VdbeCoverage(v);
VdbeCoverageIf(v, pLevel->op==OP_Next);
VdbeCoverageIf(v, pLevel->op==OP_Prev);
VdbeCoverageIf(v, pLevel->op==OP_VNext);
if( pLevel->regBignull ){
sqlite3VdbeResolveLabel(v, pLevel->addrBignull);
addr = sqlite3VdbeAddOp1(v, OP_If, pLevel->regBignull);
VdbeComment((v, "If NULL-scan done"));
VdbeCoverage(v);
sqlite3VdbeAddOp2(v, OP_Integer, 1, pLevel->regBignull);
sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->p2-1);
VdbeComment((v, "Do the NULL-scan"));
sqlite3VdbeJumpHere(v, addr);
}
#ifndef SQLITE_DISABLE_SKIPAHEAD_DISTINCT
if( addrSeek ) sqlite3VdbeJumpHere(v, addrSeek);
#endif
}else{
sqlite3VdbeResolveLabel(v, pLevel->addrCont);
|
Changes to src/whereInt.h.
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 |
int iIdxCur; /* The VDBE cursor used to access pIdx */
int addrBrk; /* Jump here to break out of the loop */
int addrNxt; /* Jump here to start the next IN combination */
int addrSkip; /* Jump here for next iteration of skip-scan */
int addrCont; /* Jump here to continue with the next loop cycle */
int addrFirst; /* First instruction of interior of the loop */
int addrBody; /* Beginning of the body of this loop */
int regBignull; /* big-null flag register */
int addrBignull; /* Jump here for next part of big-null scan */
#ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
u32 iLikeRepCntr; /* LIKE range processing counter register (times 2) */
int addrLikeRep; /* LIKE range processing address */
#endif
u8 iFrom; /* Which entry in the FROM clause */
u8 op, p3, p5; /* Opcode, P3 & P5 of the opcode that ends the loop */
|
| |
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 |
int iIdxCur; /* The VDBE cursor used to access pIdx */
int addrBrk; /* Jump here to break out of the loop */
int addrNxt; /* Jump here to start the next IN combination */
int addrSkip; /* Jump here for next iteration of skip-scan */
int addrCont; /* Jump here to continue with the next loop cycle */
int addrFirst; /* First instruction of interior of the loop */
int addrBody; /* Beginning of the body of this loop */
int regBignull; /* big-null flag reg. True if NULLs not yet scanned */
int addrBignull; /* Jump here for next part of big-null scan */
#ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
u32 iLikeRepCntr; /* LIKE range processing counter register (times 2) */
int addrLikeRep; /* LIKE range processing address */
#endif
u8 iFrom; /* Which entry in the FROM clause */
u8 op, p3, p5; /* Opcode, P3 & P5 of the opcode that ends the loop */
|
Changes to src/wherecode.c.
1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 .... 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 .... 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 |
int nExtraReg = 0; /* Number of extra registers needed */
int op; /* Instruction opcode */
char *zStartAff; /* Affinity for start of range constraint */
char *zEndAff = 0; /* Affinity for end of range constraint */
u8 bSeekPastNull = 0; /* True to seek past initial nulls */
u8 bStopAtNull = 0; /* Add condition to terminate at NULLs */
int omitTable; /* True if we use the index only */
int regBignull = 0;
pIdx = pLoop->u.btree.pIndex;
iIdxCur = pLevel->iIdxCur;
assert( nEq>=pLoop->nSkip );
/* Find any inequality constraint terms for the start and end
** of the range.
................................................................................
** so no further seeking is needed */
}else{
if( pLoop->wsFlags & WHERE_IN_EARLYOUT ){
sqlite3VdbeAddOp1(v, OP_SeekHit, iIdxCur);
}
if( regBignull ){
sqlite3VdbeAddOp2(v, OP_Integer, 0, regBignull);
}
op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
assert( op!=0 );
sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
VdbeCoverage(v);
VdbeCoverageIf(v, op==OP_Rewind); testcase( op==OP_Rewind );
................................................................................
/* Top of the loop body */
pLevel->p2 = sqlite3VdbeCurrentAddr(v);
/* Check if the index cursor is past the end of the range. */
if( nConstraint ){
if( regBignull ){
sqlite3VdbeAddOp2(v, OP_If, regBignull, sqlite3VdbeCurrentAddr(v)+3);
VdbeCoverage(v);
}
op = aEndOp[bRev*2 + endEq];
sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
testcase( op==OP_IdxGT ); VdbeCoverageIf(v, op==OP_IdxGT );
testcase( op==OP_IdxGE ); VdbeCoverageIf(v, op==OP_IdxGE );
testcase( op==OP_IdxLT ); VdbeCoverageIf(v, op==OP_IdxLT );
testcase( op==OP_IdxLE ); VdbeCoverageIf(v, op==OP_IdxLE );
}
if( regBignull ){
sqlite3VdbeAddOp2(v, OP_IfNot, regBignull, sqlite3VdbeCurrentAddr(v)+2);
VdbeCoverage(v);
if( bStopAtNull ){
op = aEndOp[bRev*2 + 0];
assert( op==OP_IdxGE || op==OP_IdxLE );
sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
testcase( op==OP_IdxGE ); VdbeCoverageIf(v, op==OP_IdxGE );
testcase( op==OP_IdxLE ); VdbeCoverageIf(v, op==OP_IdxLE );
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| > > > |
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int nExtraReg = 0; /* Number of extra registers needed */
int op; /* Instruction opcode */
char *zStartAff; /* Affinity for start of range constraint */
char *zEndAff = 0; /* Affinity for end of range constraint */
u8 bSeekPastNull = 0; /* True to seek past initial nulls */
u8 bStopAtNull = 0; /* Add condition to terminate at NULLs */
int omitTable; /* True if we use the index only */
int regBignull = 0; /* big-null flag register */
pIdx = pLoop->u.btree.pIndex;
iIdxCur = pLevel->iIdxCur;
assert( nEq>=pLoop->nSkip );
/* Find any inequality constraint terms for the start and end
** of the range.
................................................................................
** so no further seeking is needed */
}else{
if( pLoop->wsFlags & WHERE_IN_EARLYOUT ){
sqlite3VdbeAddOp1(v, OP_SeekHit, iIdxCur);
}
if( regBignull ){
sqlite3VdbeAddOp2(v, OP_Integer, 0, regBignull);
VdbeComment((v, "NULL-scan flag"));
}
op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
assert( op!=0 );
sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
VdbeCoverage(v);
VdbeCoverageIf(v, op==OP_Rewind); testcase( op==OP_Rewind );
................................................................................
/* Top of the loop body */
pLevel->p2 = sqlite3VdbeCurrentAddr(v);
/* Check if the index cursor is past the end of the range. */
if( nConstraint ){
if( regBignull ){
sqlite3VdbeAddOp2(v, OP_If, regBignull, sqlite3VdbeCurrentAddr(v)+3);
VdbeComment((v, "If in NULL-scan"));
VdbeCoverage(v);
}
op = aEndOp[bRev*2 + endEq];
sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
testcase( op==OP_IdxGT ); VdbeCoverageIf(v, op==OP_IdxGT );
testcase( op==OP_IdxGE ); VdbeCoverageIf(v, op==OP_IdxGE );
testcase( op==OP_IdxLT ); VdbeCoverageIf(v, op==OP_IdxLT );
testcase( op==OP_IdxLE ); VdbeCoverageIf(v, op==OP_IdxLE );
}
if( regBignull ){
sqlite3VdbeAddOp2(v, OP_IfNot, regBignull, sqlite3VdbeCurrentAddr(v)+2);
VdbeComment((v, "If not in NULL-scan"));
VdbeCoverage(v);
if( bStopAtNull ){
op = aEndOp[bRev*2 + 0];
assert( op==OP_IdxGE || op==OP_IdxLE );
sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
testcase( op==OP_IdxGE ); VdbeCoverageIf(v, op==OP_IdxGE );
testcase( op==OP_IdxLE ); VdbeCoverageIf(v, op==OP_IdxLE );
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