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47 events for the month beginning 2020-09-01 by user drh
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2020-09-30
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| 18:22 | Improved query optimization for multi-column indexes where the second or later columns are constrained by an IN operator and the earlier index columns limit the search to a small number of rows. Use the new OP_SeekScan opcode which does scanning of the relevant range of the index but gives up and falls back to doing a seek if the number of rows scanned grows to large, in order to guard against pathological cases where the estimated number of rows to be scanned is far too small. (check-in: f07ac3fb user: drh tags: branch-3.28) | |
| 18:06 | Improved query optimization for multi-column indexes where the second or later columns are constrained by an IN operator and the earlier index columns limit the search to a small number of rows. Use the new OP_SeekScan opcode which does scanning of the relevant range of the index but gives up and falls back to doing a seek if the number of rows scanned grows to large, in order to guard against pathological cases where the estimated number of rows to be scanned is far too small. (check-in: 4a43430f user: drh tags: trunk) | |
| 18:03 | For the OP_SeekScan opcode, adjust the number of steps run before giving up based on the estimated number of comparisons needed to perform a seek. (Closed-Leaf check-in: dc4172e6 user: drh tags: in-scan-vs-index) | |
| 17:33 | • Fixed ticket [5c4e7aa7]: Incorrect result for comparison with NULL plus 6 other changes (artifact: 1091db2a user: drh) | |
| 17:32 | Back out the incorrect optimization of check-in [e51ecadcbdef5ce6] as ticket [5c4e7aa793943803] reports a case where the optimization does not work. (check-in: 7395e96b user: drh tags: trunk) | |
| 15:46 | • Fixed ticket [66e4b0e2]: Incorrect result for LEFT JOIN plus 7 other changes (artifact: 000faea0 user: drh) | |
| 15:36 | In the query flattener when substituting expression Y in place of expression X, if X is marked has having come from an ON or USING clause of a LEFT JOIN, then be sure that all subexpressions of Y, not just the root node of Y, are similarly marked. Otherwise, if Y is an AND operator, it will be split up during WHERE clause analysis and the subexpressions will not get the special treatment needed by LEFT JOIN ON/USING clauses. Fix for ticket [66e4b0e271c47145]. (check-in: 69f9eb73 user: drh tags: trunk) | |
| 00:48 | Add an sqlite3FaultSim() call to btreeNext() to make it easier to simulate I/O errors in calls to sqlite3BtreeNext(), and in OP_SeekScan. (check-in: 29cca775 user: drh tags: in-scan-vs-index) | |
| 00:10 | In the OP_SeekScan opcode, changes to pOp must occur after the call to VdbeBranchTaken() so that the VdbeBranchTaken() attributes the branch to the correct opcode. (check-in: 61fbe7aa user: drh tags: in-scan-vs-index) | |
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2020-09-29
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| 23:52 | The OP_SeekScan opcode is a no-op if the cursor is not pointing to a valid row upon entry. (check-in: 4afc96b5 user: drh tags: in-scan-vs-index) | |
| 20:22 | Coverage testing of the OP_SeekScan opcode. Fix a problem that comes up when OP_SeekScan reaches the end of the table. (check-in: 9e57e758 user: drh tags: in-scan-vs-index) | |
| 17:29 | Improved comments on the new OP_SeekScan opcode. (check-in: 6110fdd5 user: drh tags: in-scan-vs-index) | |
| 16:05 | Improved performance by manually in-lining the sqlite3VdbeIdxKeyCompare() routine for the OP_IdxGT opcode and its kin. (check-in: 2206a2c8 user: drh tags: in-scan-vs-index) | |
| 15:32 | Typo fix to repair the early-out optimization. Also avoid unnecessary OP_SeekHit opcodes. (check-in: 8fd7d8df user: drh tags: in-scan-vs-index) | |
| 11:52 | • Ticket [c51489c3] Incorrect result from WITH RECURSIVE using DISTINCT status still Fixed with 3 other changes (artifact: 465c6275 user: drh) | |
| 01:48 | The OP_SeekScan opcode works, but using it requires disabling the IN-earlyout optimization because the OP_IfNoHope opcode might move the cursor. (check-in: f3c36b84 user: drh tags: in-scan-vs-index) | |
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2020-09-28
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| 19:51 | Revisiting the IN-scan optimization to try to fix it for the corner case where the statistics deceive the query planner into using a scan when an indexed lookup would be better. This check-in changes the code generation to do the IN-scan using a new OP_SeekScan opcode. That new opcode is designed to abandon the scan and fall back to a seek if it doesn't find a match quickly enough. For this work-in-progress check-in, OP_SeekScan is still a no-op and OP_SeekGE still ends up doing all the work. (check-in: d720b698 user: drh tags: in-scan-vs-index) | |
| 15:49 | Small performance improvement and size reduction by reducing the size of the WhereTerm object. (check-in: 43f7ddad user: drh tags: trunk) | |
| 13:34 | Avoid the possibility of integer overflow on the --pagecache option to the CLI. See forum post 10a2892377 (check-in: d3d13df3 user: drh tags: trunk) | |
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2020-09-26
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| 01:47 | • Added wiki page "checkin/2cbbabdf5ef624d809fbb40d2d312a29e0b5f02756fc0dbf6985fc8b0c8d1ade" (artifact: ac4b684e user: drh) | |
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2020-09-25
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| 14:36 | • Edit [3a576608e6f26ae8|3a576608]: Edit check-in comment. (artifact: 40be378d user: drh) | |
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2020-09-20
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| 13:33 | Remove a new assert() that the compiler finds is always true at compile-time, to avoid a compiler warning. (check-in: 8bbaee23 user: drh tags: trunk) | |
| 12:10 | Attempt to silence harmless static analyzer warnings in Lemon and in the Lemon-generated parser. (check-in: de8ce22a user: drh tags: trunk) | |
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2020-09-17
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| 11:56 | Earlier detection of corruption in the rtreecheck() SQL function to prevent a (harmless) read of an uninitialized value. (check-in: e2074b24 user: drh tags: trunk) | |
| 11:32 | Prevent use-after-free of the u.vtab.idxStr string following an OOM while generating the OP_VFilter opcode. (check-in: 751fe4ed user: drh tags: trunk) | |
| 00:47 | • Fixed ticket [c51489c3]: Incorrect result from WITH RECURSIVE using DEFAULT plus 5 other changes (artifact: bc9cfc49 user: drh) | |
| 00:46 | DISTINCT may not be ignored inside a UNION ALL common table expression. Fix for ticket [c51489c3b8f919c5] (check-in: 7d2b590d user: drh tags: trunk) | |
| 00:00 | • New ticket [c51489c3] Incorrect result from WITH RECURSIVE using DEFAULT. (artifact: bc476067 user: drh) | |
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2020-09-16
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| 19:48 | Fix a pair of assert()s in "PRAGMA foreign_key_check" that might have given a false-positive following an OOM. (check-in: 9ea3039b user: drh tags: trunk) | |
| 16:55 | Fix harmless compiler warnings in Lemon. (check-in: 6c94ba4b user: drh tags: trunk) | |
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2020-09-15
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| 12:29 | Do not invoke usleep() for more than 999999 microseconds. (check-in: 1f5ed852 user: drh tags: trunk) | |
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2020-09-10
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| 15:09 | Try again to fix the typo in the sqlite3_txn_state() documentation. (check-in: 6d1ab040 user: drh tags: trunk) | |
| 14:56 | • Edit [430c5d1da57af452|430c5d1d]: Edit check-in comment. (artifact: 347265fd user: drh) | |
| 14:54 | Fix typo in the documentation for the new sqlite3_txn_state() interface. (check-in: 23f7d017 user: drh tags: trunk) | |
| 12:41 | If an amalgamation is created using SQLITE_ENABLE_UPDATE_DELETE_LIMIT, ensure that it can still be compiled without that option by setting the SQLITE_UDL_CAPABLE_PARSER flag in the preamble. (check-in: 5b905d7d user: drh tags: trunk) | |
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2020-09-06
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| 17:40 | Remove an artifical limitation on the length of columns in the "box" output mode of the command-line shell. (check-in: 783fa887 user: drh tags: trunk) | |
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2020-09-05
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| 06:21 | Fix a bug in Lemon that might cause it to crash if there is a multi-terminal token with a space following the "|" separator. This does not affect SQLite. (check-in: 430c5d1d user: drh tags: trunk) | |
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2020-09-01
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| 12:26 | In the Lemon output, add a prefix comment that explains that the output file is automatically generated and shows the name of the source file. (check-in: d34caf3b user: drh tags: trunk) | |
| 11:20 | Lemon updates: (1) include the #defines for all tokens in the generated C file, so that the C-file can be stand-alone. (2) If the grammar begins with a %include {...} directive on line one, make that directive the header for the generated C file. (3) Enhance the lemon.html documentation. (check-in: 84d54eb3 user: drh tags: trunk) | |
| 02:02 | Improvements to the IN-early-out optimization so that it works more efficiently when there are two or more indexed IN clauses on a single table. (check-in: 49b7631e user: drh tags: branch-3.28) | |
| 01:57 | • Edit [8301da31d08b7467|8301da31]: Mark "Closed". (artifact: 32bdac4a user: drh) | |
| 01:55 | • Edit [8301da31d08b7467|8301da31]: Move to branch branch-3.28-in-early-out-fail. Edit check-in comment. (artifact: a91e43c9 user: drh) | |
| 01:53 | • Edit [e9d983c6830efdfd|e9d983c6]: Move to branch in-early-out-fail. Edit check-in comment. (artifact: a39e1790 user: drh) | |
| 01:52 | • Edit [07222dce106d2225|07222dce]: Mark "Closed". (artifact: b7ee8ddb user: drh) | |
| 01:52 | Improvements to the IN-early-out optimization so that it works more efficiently when there are two or more indexed IN clauses on a single table. (check-in: 35505c68 user: drh tags: trunk) | |
| 00:26 | Fix a harmless compiler warning. (check-in: 3ca0b7d5 user: drh tags: trunk) | |
| 00:09 | Minor changes - fix a compiler warning and add an assert(). (Closed-Leaf check-in: 07222dce user: drh tags: in-early-out-fail) | |