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empty-table-optimizations
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20 Commits

Author SHA1 Message Date
drh
235b5d0ac5 If a subquery is materialized due to an ORDER BY and that ordering is useful 
in helping to satisfy the ORDER BY or GROUP BY in the order query without
doing an extra sort, then omit the extra sort.

FossilOrigin-Name: 2fbb4dc2327ee435cb2b7a4adcddf5a9cee6dff7de96e2ecb761166427b5ddea
 2024-08-15 23:38:52 +00:00
drh
ed8e12e97b Fix an error in the OP_SeekScan opcode added by check-in [4a43430fd23f8835]. 
Problem reported by [forum:/forumpost/8cc1dc0fe9|forum post 8cc1dc0fe9].

FossilOrigin-Name: 651a13fcd16f03e89eb6228c9f3250e25910b9bbe2637f627f65ff78f8ba2059
 2023-03-24 21:24:52 +00:00
drh
8210233c7b Revise tests cases to align with the new EXPLAIN QUERY PLAN output. 
FossilOrigin-Name: 50fbd532602d2c316813046ed6be8be2991c281eb5f295c4c28520a0de73862c
 2021-03-20 15:11:29 +00:00
drh
b592d47a81 Do not attempt to use the skip-scan optimization if prior terms of the 
index are already used for non-equality constraints.
Ticket [304017f5f04a0035]

FossilOrigin-Name: d7126a9ced86cb0934d5bde2bf535e6b529c361444c99e723f29dd3eb36e7044
 2020-01-06 17:33:09 +00:00
drh
175b8f06f7 Remove support for STAT3. The sqlite_stat3 tables are ignored, if they 
exist.  STAT4 continues to work as it always has, and as it is a superset of
STAT3 is the recommended replacement.

FossilOrigin-Name: 1e17ea2fd1df4ad49138c787c8fe3207dd0c25c93f9001d52a9b69f8c12e841c
 2019-08-08 15:24:17 +00:00
drh
2ad07d96b6 Improved fix for ticket [ced41c7c7d6b4d36] that keeps skip-scan enabled, 
but avoids identifying a skip-scan as order-distinct (because it is not)
and thus forces a separate b-tree to implement the DISTINCT clause of a
query.  This undoes check-in [a871d69c6de65038] and substitutes a new fix.

FossilOrigin-Name: 89bf0399e87be76e7b264e0a35e8a6d3af0f9e71123a929c20754882b636ca70
 2019-07-30 14:22:10 +00:00
drh
822bc969f6 Disable the skip-scan optimization for DISTINCT queries. 
Fix for ticket [ced41c7c7d6b4d36]

FossilOrigin-Name: a871d69c6de65038360aa6142fbad22689fb347e526cca56bb83e695c1441fbe
 2019-07-30 01:17:03 +00:00
dan
6cf3009f6c Add further tests so that veryquick.test covers all vdbe branches. 
FossilOrigin-Name: cbc67de5a3937fa65811ed7c13e870699c895660dc2132cf9d3cf5d83364e344
 2019-04-05 20:47:15 +00:00
dan
e882551935 Add a test-control to disable the skip-scan optimization. 
FossilOrigin-Name: 650a3fe03d61068e06f3097878a777ca8ed713a769444cdb3f8be7d1e19a0b83
 2018-07-12 19:14:39 +00:00
drh
9a2e5169a4 Fix a segfault introduced by the row-value enhancement that comes up on 
a skip-scan where the first term of the index is unconstrained and the
second term is of the form "columm IN (SELECT...)".

FossilOrigin-Name: 2401ea5acfeee8042489d1db38036ff86e8a6916
 2016-09-19 11:00:42 +00:00
drh
99bbcc8287 Undo some unhelpful changes to skip-scan scoring that were added 
by the check-in [9e2b2681] that improved scoring of index scan.

FossilOrigin-Name: c7d51934a4f30d096bb79fc509fc9dd0df5d89a4
 2016-07-29 01:32:36 +00:00
drh
d3e3f0b46e The sqlite3ExprCodeGetColumn() is not guaranteed to put the result in the 
register requested.   Fix the skip-scan code generator for WITHOUT ROWID
tables so that it always checks the register and copies the result if it
lands in the wrong register.  Fix for ticket [8fd39115d8f46ece70e7d4b3].

FossilOrigin-Name: 793e206f9032d9205bdb3f447b136bed9a25fa22
 2015-07-23 16:39:33 +00:00
drh
f9df2fbdcd Adding the "noskipscan" token to an sqlite_stat1.stat field prevents an 
index for being used with the skip-scan algorithm.

FossilOrigin-Name: 00fe09505792cd0d104b2da9d040f023e30fa871
 2014-11-15 19:08:13 +00:00
drh
14f0e2128a Adjust skip-scan cost estimates slightly so that a full table scan is 
preferred over a skip-scan to a column with only two distinct values.

FossilOrigin-Name: ae9a42b268ad3f7d21a5813bb931e795c6917014
 2014-09-23 01:40:59 +00:00
dan
e96f2df3dd Changes to the output of EXPLAIN QUERY PLAN to make it clearer when a query uses the PRIMARY KEY index of a WITHOUT ROWID table. 
FossilOrigin-Name: 9268df305b90ac11e44b3107bbab5becf38860b7
 2014-05-23 17:17:06 +00:00
drh
89212fb9f9 Adjustments to the cost computation for the skip-scan query plan, to take 
into account the fact that a seek has to occur on each skip.

FossilOrigin-Name: 0769eebd028ce31375cf93509a1d3687f7b117eb
 2014-03-10 20:12:31 +00:00
drh
6c1de308f2 Make sure the WhereLoop.aLTerm[] array is large enough when processing 
the skip-scan optimization.  Fix for ticket [520070ec7fbaac].

FossilOrigin-Name: 46d040591f27be01b1860344f8a268797fe344f4
 2013-12-22 20:44:10 +00:00
drh
d24474475e Import the "PRAGMA vdbe_eqp" enhancement and the enhanced EXPLAIN formatting 
the shell from trunk.  Fix a bug in skip-scan and add a test case to prevent
a regression.

FossilOrigin-Name: f668616a29686f3ce532731c534b168e536adbb5
 2013-11-13 19:01:41 +00:00
drh
2e5ef4ed77 Improve the way that skip-scan loops are constructued. Add test cases. 
Improved the scoring of skip-scan loops.

FossilOrigin-Name: 5e75ab93881b85801cb4ebf70f2063ff7c51ac19
 2013-11-13 16:58:54 +00:00
drh
c2b23e7a98 Add test cases for skip-scan. Enhance "do_test" so that if the expected result 
is of the form "/*..*/" or "~/*..*/" it treats the expected result as a glob
pattern rather than as a regular expression.  Fix a bug in ANALYZE result
loading associated with WITHOUT ROWID tables.

FossilOrigin-Name: d3e6e9b2a74074c05429d3c341c23525504351ab
 2013-11-13 15:32:15 +00:00