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Overview
| Comment: | Remove an unreachable branch. Improvements to comments. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | vtab-IN-opt |
| Files: | files | file ages | folders |
| SHA1: |
d2fb7619b063b329b6d7ba9a16a7290e |
| User & Date: | drh 2012-12-14 17:48:08 |
Context
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2012-12-14
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| 17:54 | Optimize IN operators in the WHERE clause of queries using virtual tables. (check-in: 3d65c703 user: drh tags: trunk) | |
| 17:48 | Remove an unreachable branch. Improvements to comments. (Closed-Leaf check-in: d2fb7619 user: drh tags: vtab-IN-opt) | |
| 15:54 | Merge in all the trunk changes that have occurred since this branch was opened. (check-in: 6d507e4d user: drh tags: vtab-IN-opt) | |
Changes
Changes to src/where.c.
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** be a pointer to an sqlite3_vtab structure. Otherwise ** sqlite3ViewGetColumnNames() would have picked up the error. */ assert( pTab->azModuleArg && pTab->azModuleArg[0] ); assert( sqlite3GetVTable(pParse->db, pTab) ); /* Try once or twice. On the first attempt, allow IN optimizations. ** If an IN optimization is accepted, but does not set the ** pInfo->aConstrainUsage.omit flag, then it will not work (because it ** will allow duplicate rows in the result set) so try again with ** IN optimizations disabled. */ for(bAllowIN=1; bAllowIN>=0; bAllowIN--){ /* Set the aConstraint[].usable fields and initialize all ** output variables to zero. ** ** aConstraint[].usable is true for constraints where the right-hand ** side contains only references to tables to the left of the current ** table. In other words, if the constraint is of the form: ** |
| | | | > > | > > |
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** be a pointer to an sqlite3_vtab structure. Otherwise ** sqlite3ViewGetColumnNames() would have picked up the error. */ assert( pTab->azModuleArg && pTab->azModuleArg[0] ); assert( sqlite3GetVTable(pParse->db, pTab) ); /* Try once or twice. On the first attempt, allow IN optimizations. ** If an IN optimization is accepted by the virtual table xBestIndex ** method, but the pInfo->aConstrainUsage.omit flag is not set, then ** the query will not work because it might allow duplicate rows in ** output. In that case, run the xBestIndex method a second time ** without the IN constraints. Usually this loop only runs once. ** The loop will exit using a "break" statement. */ for(bAllowIN=1; 1; bAllowIN--){ assert( bAllowIN==0 || bAllowIN==1 ); /* Set the aConstraint[].usable fields and initialize all ** output variables to zero. ** ** aConstraint[].usable is true for constraints where the right-hand ** side contains only references to tables to the left of the current ** table. In other words, if the constraint is of the form: ** |