From cdb2f60743dad83e108e4600e9eab6a935c311ec Mon Sep 17 00:00:00 2001
From: drh <drh@noemail.net>
Date: Wed, 4 Oct 2017 05:59:54 +0000
Subject: [PATCH] Remove a redundant restriction from the query flattener.

FossilOrigin-Name: 66629b2a0997ceedcfb38553f2200466b6c4e352ea00f8a0a7cb67a660c19523
---
 manifest      | 12 ++++++------
 manifest.uuid |  2 +-
 src/select.c  | 16 +++++++++++-----
 3 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/manifest b/manifest
index b5978e8b5e..37d62ef094 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\sa\sminor\stypo\sin\sthe\squery\sflattener\sheader\scomment.\s\sNo\scode\schanges.
-D 2017-10-04T02:30:45.805
+C Remove\sa\sredundant\srestriction\sfrom\sthe\squery\sflattener.
+D 2017-10-04T05:59:54.466
 F Makefile.in 4bc36d913c2e3e2d326d588d72f618ac9788b2fd4b7efda61102611a6495c3ff
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 6033b51b6aea702ea059f6ab2d47b1d3cef648695f787247dd4fb395fe60673f
@@ -458,7 +458,7 @@ F src/printf.c 40aee47ae9be4bd3dbdc8968bd07fddc027be8edec8daddf24d3391d36698a1c
 F src/random.c 80f5d666f23feb3e6665a6ce04c7197212a88384
 F src/resolve.c 4324a94573b1e29286f8121e4881db59eaedc014afeb274c8d3e07ed282e0e20
 F src/rowset.c 7b7e7e479212e65b723bf40128c7b36dc5afdfac
-F src/select.c 4248b28ec9db68653d3ea5137b7c7f5bad52451486ccf1a2247cd39ca3b9e35c
+F src/select.c 8a506e0a27799e96276aea0b5fd1591762905bd572f326d2886cb74f5ceb5f4a
 F src/shell.c c1206a23d9239f8f51751d3be9b8c3b02fa4103546bea1add7f864d84a8276ab
 F src/shell.c.in bb9720a8c5c98d3984b16ab7540e7142bcae959666ecf248bfc523a1d44220ee
 F src/sqlite.h.in ab4f8a29d1580dfaeb6891fa1b83cff8229ba0daa56994707ceaca71495d9ab7
@@ -1655,7 +1655,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 772b0db1469c9e1c2728cf65dd070e29c624e75c3a5da72ee1297f15d758dd13
-R 5f83cd7ed7c6212a42bd83dd65e953e5
+P d050dc605c24bcf60c0c47d13612ad53b871d3d4eff681c0c1b933acf53fb5ee
+R 0deb4a35d3602fd5f83a95efc798c5e9
 U drh
-Z 4de48cca341b3f710b375c35ea16b291
+Z 70da60dffddabeaa8e38379103c330a2
diff --git a/manifest.uuid b/manifest.uuid
index 0509f11b51..c73fafb1b1 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-d050dc605c24bcf60c0c47d13612ad53b871d3d4eff681c0c1b933acf53fb5ee
\ No newline at end of file
+66629b2a0997ceedcfb38553f2200466b6c4e352ea00f8a0a7cb67a660c19523
\ No newline at end of file
diff --git a/src/select.c b/src/select.c
index 0ef316a540..6b5770e737 100644
--- a/src/select.c
+++ b/src/select.c
@@ -3393,8 +3393,9 @@ static void substSelect(
 **
 **  (22)  The subquery may not be a recursive CTE.
 **
-**  (23)  If the outer query is a recursive CTE, then the sub-query may not be
-**        a compound query. This restriction is because transforming the
+**  (**)  Subsumed into restriction (17d3).  Was: If the outer query is
+**        a recursive CTE, then the sub-query may not be a compound query.
+**        This restriction is because transforming the
 **        parent to a compound query confuses the code that handles
 **        recursive queries in multiSelect().
 **
@@ -3475,9 +3476,6 @@ static int flattenSubquery(
   if( pSub->selFlags & (SF_Recursive) ){
     return 0; /* Restrictions (22) */
   }
-  if( (p->selFlags & SF_Recursive) && pSub->pPrior ){
-    return 0; /* Restriction (23) */
-  }
 
   /*
   ** If the subquery is the right operand of a LEFT JOIN, then the
@@ -3551,6 +3549,14 @@ static int flattenSubquery(
     }
   }
 
+  /* Ex-restriction (23):
+  ** The only way that the recursive part of a CTE can contain a compound
+  ** subquery is for the subquery to be one term of a join.  But if the
+  ** subquery is a join, then the flattening has already been stopped by
+  ** restriction (17d3)
+  */
+  assert( (p->selFlags & SF_Recursive)==0 || pSub->pPrior==0 );
+
   /***** If we reach this point, flattening is permitted. *****/
   SELECTTRACE(1,pParse,p,("flatten %s.%p from term %d\n",
                    pSub->zSelName, pSub, iFrom));
-- 
2.47.2