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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
| ||
| 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 */
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Changes to src/wherecode.c.
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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;
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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