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Overview
Comment: | Alternative implementation of exprCompareVariable(). |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | partial-index-variables |
Files: | files | file ages | folders |
SHA3-256: |
b959c6297c151150ea2dca24aa1f68f3 |
User & Date: | drh 2017-06-28 21:47:16.657 |
Original Comment: | Alternative implementation of exprCompareVariable(). Need to run tests on both this branch and the original to see which one to go with. |
Context
2017-06-29
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01:23 | Fix the exprCompareVariable() routine so that it works for non-UTF8 text. (Closed-Leaf check-in: 25acd9658b user: drh tags: partial-index-variables) | |
2017-06-28
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21:47 | Alternative implementation of exprCompareVariable(). (check-in: b959c6297c user: drh tags: partial-index-variables) | |
18:25 | Make the query planners use of partial indexes based on bound variables responsive to the SQLITE_DBCONFIG_ENABLE_QPSG setting. (check-in: a934dd14ac user: drh tags: partial-index-variables) | |
Changes
Changes to src/expr.c.
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4671 4672 4673 4674 4675 4676 4677 | ** Additionally, if pExpr is a simple SQL value and the value is the ** same as that currently bound to variable pVar, non-zero is returned. ** Otherwise, if the values are not the same or if pExpr is not a simple ** SQL value, zero is returned. */ static int exprCompareVariable(Parse *pParse, Expr *pVar, Expr *pExpr){ int res = 0; | | | | | < < < | > < < < < < | | | | | < < < | 4671 4672 4673 4674 4675 4676 4677 4678 4679 4680 4681 4682 4683 4684 4685 4686 4687 4688 4689 4690 4691 4692 4693 4694 4695 4696 4697 | ** Additionally, if pExpr is a simple SQL value and the value is the ** same as that currently bound to variable pVar, non-zero is returned. ** Otherwise, if the values are not the same or if pExpr is not a simple ** SQL value, zero is returned. */ static int exprCompareVariable(Parse *pParse, Expr *pVar, Expr *pExpr){ int res = 0; int iVar; sqlite3_value *pL, *pR = 0; sqlite3ValueFromExpr(pParse->db, pExpr, SQLITE_UTF8, SQLITE_AFF_BLOB, &pR); if( pR ){ iVar = pVar->iColumn; sqlite3VdbeSetVarmask(pParse->pVdbe, iVar); pL = sqlite3VdbeGetBoundValue(pParse->pReprepare, iVar, SQLITE_AFF_BLOB); if( pL && 0==sqlite3MemCompare(pL, pR, 0) ){ res = 1; } sqlite3ValueFree(pR); sqlite3ValueFree(pL); } return res; } /* ** Do a deep comparison of two expression trees. Return 0 if the two |
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4721 4722 4723 4724 4725 4726 4727 | ** returns 2, then you do not really know for certain if the two ** expressions are the same. But if you get a 0 or 1 return, then you ** can be sure the expressions are the same. In the places where ** this routine is used, it does not hurt to get an extra 2 - that ** just might result in some slightly slower code. But returning ** an incorrect 0 or 1 could lead to a malfunction. ** | > > > > | < < < | | 4711 4712 4713 4714 4715 4716 4717 4718 4719 4720 4721 4722 4723 4724 4725 4726 4727 4728 4729 4730 | ** returns 2, then you do not really know for certain if the two ** expressions are the same. But if you get a 0 or 1 return, then you ** can be sure the expressions are the same. In the places where ** this routine is used, it does not hurt to get an extra 2 - that ** just might result in some slightly slower code. But returning ** an incorrect 0 or 1 could lead to a malfunction. ** ** If pParse is not NULL then TK_VARIABLE terms in pA with bindings in ** pParse->pReprepare can be matched against literals in pB. The ** pParse->pVdbe->expmask bitmask is updated for each variable referenced. ** If pParse is NULL (the normal case) then any TK_VARIABLE term in ** Argument pParse should normally be NULL. If it is not NULL and pA or ** pB causes a return value of 2. */ int sqlite3ExprCompare(Parse *pParse, Expr *pA, Expr *pB, int iTab){ u32 combinedFlags; if( pA==0 || pB==0 ){ return pB==pA ? 0 : 2; } if( pParse && pA->op==TK_VARIABLE && exprCompareVariable(pParse, pA, pB) ){ |
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4829 4830 4831 4832 4833 4834 4835 4836 4837 4838 4839 4840 4841 4842 | ** pE1: x!=?1 pE2: x IS NOT NULL Result: true ** pE1: x IS NULL pE2: x IS NOT NULL Result: false ** pE1: x IS ?2 pE2: x IS NOT NULL Reuslt: false ** ** When comparing TK_COLUMN nodes between pE1 and pE2, if pE2 has ** Expr.iTable<0 then assume a table number given by iTab. ** ** When in doubt, return false. Returning true might give a performance ** improvement. Returning false might cause a performance reduction, but ** it will always give the correct answer and is hence always safe. */ int sqlite3ExprImpliesExpr(Parse *pParse, Expr *pE1, Expr *pE2, int iTab){ if( sqlite3ExprCompare(pParse, pE1, pE2, iTab)==0 ){ return 1; | > > > > > | 4820 4821 4822 4823 4824 4825 4826 4827 4828 4829 4830 4831 4832 4833 4834 4835 4836 4837 4838 | ** pE1: x!=?1 pE2: x IS NOT NULL Result: true ** pE1: x IS NULL pE2: x IS NOT NULL Result: false ** pE1: x IS ?2 pE2: x IS NOT NULL Reuslt: false ** ** When comparing TK_COLUMN nodes between pE1 and pE2, if pE2 has ** Expr.iTable<0 then assume a table number given by iTab. ** ** If pParse is not NULL, then the values of bound variables in pE1 are ** compared against literal values in pE2 and pParse->pVdbe->expmask is ** modified to record which bound variables are referenced. If pParse ** is NULL, then false will be returned if pE1 contains any bound variables. ** ** When in doubt, return false. Returning true might give a performance ** improvement. Returning false might cause a performance reduction, but ** it will always give the correct answer and is hence always safe. */ int sqlite3ExprImpliesExpr(Parse *pParse, Expr *pE1, Expr *pE2, int iTab){ if( sqlite3ExprCompare(pParse, pE1, pE2, iTab)==0 ){ return 1; |
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