diff options
| -rw-r--r-- | manifest | 12 | ||||
| -rw-r--r-- | manifest.uuid | 2 | ||||
| -rw-r--r-- | src/select.c | 19 |
3 files changed, 19 insertions, 14 deletions
@@ -1,5 +1,5 @@ -C Fix\sSTAT3\sso\sthat\sit\sworks\swith\sthe\snew\suninitialized\sregister\slogic\sof\nthe\sVDBE.\s\sTicket\s[7bbfb7d4422ff] -D 2011-12-11T02:30:35.672 +C Update\scomments\sdescribing\sthe\sflattening\soptimization\sin\sselect.c. +D 2011-12-11T21:51:04.519 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f F Makefile.in 5b4a3e12a850b021547e43daf886b25133b44c07 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23 @@ -180,7 +180,7 @@ F src/printf.c 7ffb4ebb8b341f67e049695ba031da717b3d2699 F src/random.c cd4a67b3953b88019f8cd4ccd81394a8ddfaba50 F src/resolve.c 3d3e80a98f203ac6b9329e9621e29eda85ddfd40 F src/rowset.c 69afa95a97c524ba6faf3805e717b5b7ae85a697 -F src/select.c f38d6bb54dbe42409b66b038be24765f68b5d44b +F src/select.c a1d075db66a0ea42807353501b62997969e5be79 F src/shell.c a1eadb2fdbfa45e54307263f0c8da8ee8cd61b8b F src/sqlite.h.in 1dc07194eb1a2c69c8ef75f88022b170be08024a F src/sqlite3ext.h 6904f4aadf976f95241311fbffb00823075d9477 @@ -978,7 +978,7 @@ F tool/tostr.awk e75472c2f98dd76e06b8c9c1367f4ab07e122d06 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f F tool/warnings-clang.sh 9f406d66e750e8ac031c63a9ef3248aaa347ef2a F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381 -P 1e6a698aab9270637d3ea00fd6b0e94f4172e875 -R b14f97101207c69b3c216a1f2d4f412b +P d11a57985c394772043c63d4c2b534944be0a664 +R db74426b5ff988e285b71512d50b85b4 U drh -Z ed714f23f92d49472af328d21dd14bdc +Z fcdcb7d7647c15fa01d78b530015f5fb diff --git a/manifest.uuid b/manifest.uuid index 2526b92bc..9f7b7a620 100644 --- a/manifest.uuid +++ b/manifest.uuid @@ -1 +1 @@ -d11a57985c394772043c63d4c2b534944be0a664
\ No newline at end of file +dab4c137a852222f11179fa2ade52d17a4206dd2
\ No newline at end of file diff --git a/src/select.c b/src/select.c index f0f4b6a5f..188050e8d 100644 --- a/src/select.c +++ b/src/select.c @@ -2588,9 +2588,8 @@ static void substSelect( #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) /* -** This routine attempts to flatten subqueries in order to speed -** execution. It returns 1 if it makes changes and 0 if no flattening -** occurs. +** This routine attempts to flatten subqueries as a performance optimization. +** This routine returns 1 if it makes changes and 0 if no flattening occurs. ** ** To understand the concept of flattening, consider the following ** query: @@ -2632,7 +2631,10 @@ static void substSelect( ** (6) The subquery does not use aggregates or the outer query is not ** DISTINCT. ** -** (7) The subquery has a FROM clause. +** (7) The subquery has a FROM clause. TODO: For subqueries without +** A FROM clause, consider adding a FROM close with the special +** table sqlite_once that consists of a single row containing a +** single NULL. ** ** (8) The subquery does not use LIMIT or the outer query is not a join. ** @@ -2665,11 +2667,14 @@ static void substSelect( ** ** * is not itself part of a compound select, ** * is not an aggregate or DISTINCT query, and -** * has no other tables or sub-selects in the FROM clause. +** * is not a join ** ** The parent and sub-query may contain WHERE clauses. Subject to ** rules (11), (13) and (14), they may also contain ORDER BY, -** LIMIT and OFFSET clauses. +** LIMIT and OFFSET clauses. The subquery cannot use any compound +** operator other than UNION ALL because all the other compound +** operators have an implied DISTINCT which is disallowed by +** restriction (4). ** ** (18) If the sub-query is a compound select, then all terms of the ** ORDER by clause of the parent must be simple references to @@ -2681,7 +2686,7 @@ static void substSelect( ** (20) If the sub-query is a compound select, then it must not use ** an ORDER BY clause. Ticket #3773. We could relax this constraint ** somewhat by saying that the terms of the ORDER BY clause must -** appear as unmodified result columns in the outer query. But +** appear as unmodified result columns in the outer query. But we ** have other optimizations in mind to deal with that case. ** ** (21) The subquery does not use LIMIT or the outer query is not |