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Overview
Comment: | Simplification of the WHERE loop code generator for NULLS LAST saves a few CPU cycles and about a hundred bytes of code space. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | nulls-last |
Files: | files | file ages | folders |
SHA3-256: |
e3ed2f496f51234a8f81d90d47ba603b |
User & Date: | drh 2019-08-23 16:12:20.533 |
Context
2019-08-23
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17:00 | Additional simplifications of the WHERE loop code generator logic for NULLS LAST. (check-in: 1383680d92 user: drh tags: nulls-last) | |
16:12 | Simplification of the WHERE loop code generator for NULLS LAST saves a few CPU cycles and about a hundred bytes of code space. (check-in: e3ed2f496f user: drh tags: nulls-last) | |
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: bf875e1a25 user: drh tags: nulls-last) | |
Changes
Changes to src/wherecode.c.
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1667 1668 1669 1670 1671 1672 1673 | if( sqlite3ExprIsVector(pRight)==0 ){ disableTerm(pLevel, pRangeStart); }else{ startEq = 1; } bSeekPastNull = 0; }else if( bSeekPastNull ){ | < < > > | 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 | if( sqlite3ExprIsVector(pRight)==0 ){ disableTerm(pLevel, pRangeStart); }else{ startEq = 1; } bSeekPastNull = 0; }else if( bSeekPastNull ){ startEq = 0; sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq); start_constraints = 1; nConstraint++; }else if( regBignull ){ sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq); start_constraints = 1; nConstraint++; } codeApplyAffinity(pParse, regBase, nConstraint - bSeekPastNull, zStartAff); if( pLoop->nSkip>0 && nConstraint==pLoop->nSkip ){ |
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1701 1702 1703 1704 1705 1706 1707 1708 1709 | VdbeCoverageIf(v, op==OP_Rewind); testcase( op==OP_Rewind ); VdbeCoverageIf(v, op==OP_Last); testcase( op==OP_Last ); VdbeCoverageIf(v, op==OP_SeekGT); testcase( op==OP_SeekGT ); VdbeCoverageIf(v, op==OP_SeekGE); testcase( op==OP_SeekGE ); VdbeCoverageIf(v, op==OP_SeekLE); testcase( op==OP_SeekLE ); VdbeCoverageIf(v, op==OP_SeekLT); testcase( op==OP_SeekLT ); if( regBignull ){ sqlite3VdbeAddOp2(v, OP_Goto, 0, sqlite3VdbeCurrentAddr(v)+2); | > > > < | < | < < < < < < < < < | | | | < | | | < | 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 | VdbeCoverageIf(v, op==OP_Rewind); testcase( op==OP_Rewind ); VdbeCoverageIf(v, op==OP_Last); testcase( op==OP_Last ); VdbeCoverageIf(v, op==OP_SeekGT); testcase( op==OP_SeekGT ); VdbeCoverageIf(v, op==OP_SeekGE); testcase( op==OP_SeekGE ); VdbeCoverageIf(v, op==OP_SeekLE); testcase( op==OP_SeekLE ); VdbeCoverageIf(v, op==OP_SeekLT); testcase( op==OP_SeekLT ); assert( bSeekPastNull==0 || bStopAtNull==0 ); if( regBignull ){ assert( bSeekPastNull==1 || bStopAtNull==1 ); assert( bStopAtNull==startEq ); sqlite3VdbeAddOp2(v, OP_Goto, 0, sqlite3VdbeCurrentAddr(v)+2); op = aStartOp[(nConstraint>1)*4 + 2 + bRev]; sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint-startEq); VdbeCoverage(v); VdbeCoverageIf(v, op==OP_Rewind); testcase( op==OP_Rewind ); VdbeCoverageIf(v, op==OP_Last); testcase( op==OP_Last ); VdbeCoverageIf(v, op==OP_SeekGE); testcase( op==OP_SeekGE ); VdbeCoverageIf(v, op==OP_SeekLE); testcase( op==OP_SeekLE ); assert( op==OP_Rewind || op==OP_Last || op==OP_SeekGE || op==OP_SeekLE); } } /* Load the value for the inequality constraint at the end of the ** range (if any). */ nConstraint = nEq; |
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