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Overview
| Comment: | Clearer presentation of the logic. No functional changes. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | skip-scan-improvement |
| Files: | files | file ages | folders |
| SHA1: |
a3dcf6db76cc09bdfedb1bbeba3b359b |
| User & Date: | drh 2016-02-22 21:19:54 |
Context
|
2016-02-22
| ||
| 23:14 | Avoid an unnecessary seek operation some corner-case skip-scan operations. check-in: 2a6003a9 user: drh tags: trunk | |
| 21:19 | Clearer presentation of the logic. No functional changes. Closed-Leaf check-in: a3dcf6db user: drh tags: skip-scan-improvement | |
| 20:52 | Avoid an unnecessary seek operation on some corner-case skip-scans. check-in: 38e837e6 user: drh tags: skip-scan-improvement | |
Changes
Changes to src/wherecode.c.
1208 1208 }else if( bSeekPastNull ){ 1209 1209 sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq); 1210 1210 nConstraint++; 1211 1211 startEq = 0; 1212 1212 start_constraints = 1; 1213 1213 } 1214 1214 codeApplyAffinity(pParse, regBase, nConstraint - bSeekPastNull, zStartAff); 1215 - if( pLoop->nSkip==0 || nConstraint>pLoop->nSkip ){ 1215 + if( pLoop->nSkip>0 && nConstraint==pLoop->nSkip ){ 1216 + /* The skip-scan logic inside the call to codeAllEqualityConstraints() 1217 + ** above has already left the cursor sitting on the correct row, 1218 + ** so no further seeking is needed */ 1219 + }else{ 1216 1220 op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev]; 1217 1221 assert( op!=0 ); 1218 1222 sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint); 1219 1223 VdbeCoverage(v); 1220 1224 VdbeCoverageIf(v, op==OP_Rewind); testcase( op==OP_Rewind ); 1221 1225 VdbeCoverageIf(v, op==OP_Last); testcase( op==OP_Last ); 1222 1226 VdbeCoverageIf(v, op==OP_SeekGT); testcase( op==OP_SeekGT ); 1223 1227 VdbeCoverageIf(v, op==OP_SeekGE); testcase( op==OP_SeekGE ); 1224 1228 VdbeCoverageIf(v, op==OP_SeekLE); testcase( op==OP_SeekLE ); 1225 1229 VdbeCoverageIf(v, op==OP_SeekLT); testcase( op==OP_SeekLT ); 1226 1230 } 1227 - 1231 + 1228 1232 /* Load the value for the inequality constraint at the end of the 1229 1233 ** range (if any). 1230 1234 */ 1231 1235 nConstraint = nEq; 1232 1236 if( pRangeEnd ){ 1233 1237 Expr *pRight = pRangeEnd->pExpr->pRight; 1234 1238 sqlite3ExprCacheRemove(pParse, regBase+nEq, 1);