| From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 |
| From: Darwin Huang <huangdarwin@chromium.org> |
| Date: Thu, 16 Jan 2020 15:41:01 -0800 |
| Subject: [PATCH 24/25] Back away from LEFT JOIN optimization |
| |
| Backports https://sqlite.org/src/info/862974312edf00e9d1068115d1a39b7235b7db68b6d86b81d38a12f025a4748e |
| |
| Bug: 1042578 |
| --- |
| third_party/sqlite/patched/src/select.c | 8 ++++++-- |
| third_party/sqlite/patched/test/join.test | 13 +++++++++++++ |
| 2 files changed, 19 insertions(+), 2 deletions(-) |
| |
| diff --git a/third_party/sqlite/patched/src/select.c b/third_party/sqlite/patched/src/select.c |
| index 4ed359800a2b..ec764996fb1a 100644 |
| --- a/third_party/sqlite/patched/src/select.c |
| +++ b/third_party/sqlite/patched/src/select.c |
| @@ -3596,6 +3596,7 @@ static void substSelect( |
| ** (3b) the FROM clause of the subquery may not contain a virtual |
| ** table and |
| ** (3c) the outer query may not be an aggregate. |
| +** (3d) the outer query may not be DISTINCT. |
| ** |
| ** (4) The subquery can not be DISTINCT. |
| ** |
| @@ -3792,8 +3793,11 @@ static int flattenSubquery( |
| */ |
| if( (pSubitem->fg.jointype & JT_OUTER)!=0 ){ |
| isLeftJoin = 1; |
| - if( pSubSrc->nSrc>1 || isAgg || IsVirtual(pSubSrc->a[0].pTab) ){ |
| - /* (3a) (3c) (3b) */ |
| + if( pSubSrc->nSrc>1 /* (3a) */ |
| + || isAgg /* (3b) */ |
| + || IsVirtual(pSubSrc->a[0].pTab) /* (3c) */ |
| + || (p->selFlags & SF_Distinct)!=0 /* (3d) */ |
| + ){ |
| return 0; |
| } |
| } |
| diff --git a/third_party/sqlite/patched/test/join.test b/third_party/sqlite/patched/test/join.test |
| index c6c615f1351c..1c75041eb5ea 100644 |
| --- a/third_party/sqlite/patched/test/join.test |
| +++ b/third_party/sqlite/patched/test/join.test |
| @@ -905,5 +905,18 @@ do_execsql_test join-18.4 { |
| SELECT NOT(v0.a IS FALSE) FROM v0 |
| } {1} |
| |
| +# 2019-12-18 problem with a LEFT JOIN where the RHS is a view. |
| +# Detected by Yongheng and Rui. |
| +# Follows from the optimization attempt of check-in 41c27bc0ff1d3135 |
| +# on 2017-04-18 |
| +# |
| +reset_db |
| +do_execsql_test join-22.10 { |
| + CREATE TABLE t0(a, b); |
| + CREATE INDEX t0a ON t0(a); |
| + INSERT INTO t0 VALUES(10,10),(10,11),(10,12); |
| + SELECT DISTINCT c FROM t0 LEFT JOIN (SELECT a+1 AS c FROM t0) ORDER BY c ; |
| +} {11} |
| + |
| finish_test |
| |
| -- |
| 2.25.0.rc1.283.g88dfdc4193-goog |
| |
