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Overview
| Comment: | Additional simplifications of the WHERE loop code generator logic for NULLS LAST. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | nulls-last |
| Files: | files | file ages | folders |
| SHA3-256: |
1383680d927d7d703933be7653c00191 |
| User & Date: | drh 2019-08-23 17:00:22 |
Context
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2019-08-23
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| 17:09 | Revise the VDBE comments for NULL-scan so that they also work make sense when reading a NULLS FIRST plan. check-in: bfe79378 user: drh tags: nulls-last | |
| 17:00 | Additional simplifications of the WHERE loop code generator logic for NULLS LAST. check-in: 1383680d 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: e3ed2f49 user: drh tags: nulls-last | |
Changes
Changes to src/wherecode.c.
1704 1704 VdbeCoverageIf(v, op==OP_SeekGE); testcase( op==OP_SeekGE ); 1705 1705 VdbeCoverageIf(v, op==OP_SeekLE); testcase( op==OP_SeekLE ); 1706 1706 VdbeCoverageIf(v, op==OP_SeekLT); testcase( op==OP_SeekLT ); 1707 1707 1708 1708 assert( bSeekPastNull==0 || bStopAtNull==0 ); 1709 1709 if( regBignull ){ 1710 1710 assert( bSeekPastNull==1 || bStopAtNull==1 ); 1711 + assert( bSeekPastNull==!bStopAtNull ); 1711 1712 assert( bStopAtNull==startEq ); 1712 1713 sqlite3VdbeAddOp2(v, OP_Goto, 0, sqlite3VdbeCurrentAddr(v)+2); 1713 1714 op = aStartOp[(nConstraint>1)*4 + 2 + bRev]; 1714 1715 sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, 1715 1716 nConstraint-startEq); 1716 1717 VdbeCoverage(v); 1717 1718 VdbeCoverageIf(v, op==OP_Rewind); testcase( op==OP_Rewind ); ................................................................................ 1762 1763 1763 1764 /* Top of the loop body */ 1764 1765 pLevel->p2 = sqlite3VdbeCurrentAddr(v); 1765 1766 1766 1767 /* Check if the index cursor is past the end of the range. */ 1767 1768 if( nConstraint ){ 1768 1769 if( regBignull ){ 1770 + /* Except, skip the end-of-range check while doing the NULL-scan */ 1769 1771 sqlite3VdbeAddOp2(v, OP_IfNot, regBignull, sqlite3VdbeCurrentAddr(v)+3); 1770 1772 VdbeComment((v, "If NULL-scan active")); 1771 1773 VdbeCoverage(v); 1772 1774 } 1773 1775 op = aEndOp[bRev*2 + endEq]; 1774 1776 sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint); 1775 1777 testcase( op==OP_IdxGT ); VdbeCoverageIf(v, op==OP_IdxGT ); 1776 1778 testcase( op==OP_IdxGE ); VdbeCoverageIf(v, op==OP_IdxGE ); 1777 1779 testcase( op==OP_IdxLT ); VdbeCoverageIf(v, op==OP_IdxLT ); 1778 1780 testcase( op==OP_IdxLE ); VdbeCoverageIf(v, op==OP_IdxLE ); 1779 1781 } 1780 1782 if( regBignull ){ 1783 + /* During a NULL-scan, check to see if we have reached the end of 1784 + ** the NULLs */ 1785 + assert( bSeekPastNull==!bStopAtNull ); 1786 + assert( bSeekPastNull+bStopAtNull==1 ); 1787 + assert( nConstraint+bSeekPastNull>0 ); 1781 1788 sqlite3VdbeAddOp2(v, OP_If, regBignull, sqlite3VdbeCurrentAddr(v)+2); 1782 1789 VdbeComment((v, "If NULL-scan pending")); 1783 1790 VdbeCoverage(v); 1784 - if( bStopAtNull ){ 1785 - op = aEndOp[bRev*2 + 0]; 1786 - assert( op==OP_IdxGE || op==OP_IdxLE ); 1787 - sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint); 1788 - testcase( op==OP_IdxGE ); VdbeCoverageIf(v, op==OP_IdxGE ); 1789 - testcase( op==OP_IdxLE ); VdbeCoverageIf(v, op==OP_IdxLE ); 1790 - }else{ 1791 - op = aEndOp[bRev*2 + endEq]; 1792 - sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint+1); 1793 - testcase( op==OP_IdxGT ); VdbeCoverageIf(v, op==OP_IdxGT ); 1794 - testcase( op==OP_IdxGE ); VdbeCoverageIf(v, op==OP_IdxGE ); 1795 - testcase( op==OP_IdxLT ); VdbeCoverageIf(v, op==OP_IdxLT ); 1796 - testcase( op==OP_IdxLE ); VdbeCoverageIf(v, op==OP_IdxLE ); 1797 - } 1791 + op = aEndOp[bRev*2 + bSeekPastNull]; 1792 + sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, 1793 + nConstraint+bSeekPastNull); 1794 + testcase( op==OP_IdxGT ); VdbeCoverageIf(v, op==OP_IdxGT ); 1795 + testcase( op==OP_IdxGE ); VdbeCoverageIf(v, op==OP_IdxGE ); 1796 + testcase( op==OP_IdxLT ); VdbeCoverageIf(v, op==OP_IdxLT ); 1797 + testcase( op==OP_IdxLE ); VdbeCoverageIf(v, op==OP_IdxLE ); 1798 1798 } 1799 1799 1800 1800 if( pLoop->wsFlags & WHERE_IN_EARLYOUT ){ 1801 1801 sqlite3VdbeAddOp2(v, OP_SeekHit, iIdxCur, 1); 1802 1802 } 1803 1803 1804 1804 /* Seek the table cursor, if required */