Never flatten a CTE that is labeled MATERIALIZED. This is really something

of a bug fix because the documentation says that a MATERIALIZED CTE is an
optimization barrier.

FossilOrigin-Name: b7ef9796f548ce43e06673f86bbec68157aae5e4ee8451e1d87ee5f70af1bb27

manifest

@@ -1,5 +1,5 @@
-C When\sa\squery\sis\sinside\san\sAS\sMATERIALIZED\sCTE,\sdo\snot\sattempt\sthe\nomit-ORDER-BY\soptimization.\s\sIf\sthe\sdeveloper\sspecifies\sMATERIALIZED,\nthat\smeans\she\swants\sthe\ssort\sto\sactually\shappen.
-D 2023-08-02T00:09:15.460
+C Never\sflatten\sa\sCTE\sthat\sis\slabeled\sMATERIALIZED.\s\sThis\sis\sreally\ssomething\nof\sa\sbug\sfix\sbecause\sthe\sdocumentation\ssays\sthat\sa\sMATERIALIZED\sCTE\sis\san\noptimization\sbarrier.
+D 2023-08-02T11:06:27.030
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -643,7 +643,7 @@ F src/printf.c e3ba080e2f409f9bfcc8d34724e6fc160e9c718dc92d0548f6b71b8b6f860ce2
 F src/random.c 606b00941a1d7dd09c381d3279a058d771f406c5213c9932bbd93d5587be4b9c
 F src/resolve.c 37953a5f36c60bea413c3c04efcd433b6177009f508ef2ace0494728912fe2e9
 F src/rowset.c 8432130e6c344b3401a8874c3cb49fefe6873fec593294de077afea2dce5ec97
-F src/select.c 0ea15e379b2eb09d1a803499438b957c59af7264996903ec9b9a4aeb0402293b
+F src/select.c 10ff496138ffa5bf5c3d9c7808b7558cb9b398d12062c464037167748075a13f
 F src/shell.c.in 694aaf751f00610381533d4a31c83d142cfc83ef91ef65e2aa6912ace7c39b40
 F src/sqlite.h.in 7b07a33d2af82ee974aa91e6294abce0282b2f4c5934b291d2fff961810dd867
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
@@ -2049,11 +2049,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P e989a37ff9d5b52e0090d59be077ad2260c8df5d4c2c2d8088b1160de64dffd4
-R 85471d4376eb004f17191da107252ebb
-T *branch * materialize-order-by
-T *sym-materialize-order-by *
-T -sym-trunk *
+P aa769ee7477171f26a091cadff98aa4f48da7752ade20b405a95c4525456f62e
+R 5d3359f6c6d5e2c6f797651e2c52272a
 U drh
-Z 34b88ebfe26392ded7967d5b47a75b8d
+Z d3d190ae3372df83f9be614d98609288
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-aa769ee7477171f26a091cadff98aa4f48da7752ade20b405a95c4525456f62e
+b7ef9796f548ce43e06673f86bbec68157aae5e4ee8451e1d87ee5f70af1bb27

src/select.c

@@ -7314,7 +7314,14 @@ int sqlite3Select(
     **            (a)  The outer query has a different ORDER BY clause
     **            (b)  The subquery is part of a join
     **          See forum post 062d576715d277c8
+    **
+    ** The above cases might get an incorrect result if ORDER BY is omitted.
+    ** The following constraints are not required for correct answers, but are
+    ** included in order to give developers more control over when a sort
+    ** occurs:
+    **
     **    (6)   The subquery is really a MATERIALIZED CTE
+    **    (7)   The OmitOrderBy optimization is disabled
     */
     if( pSub->pOrderBy!=0
      && (p->pOrderBy!=0 || pTabList->nSrc>1)      /* Condition (5) */
@@ -7322,7 +7329,7 @@ int sqlite3Select(
      && (pSub->selFlags & SF_OrderByReqd)==0      /* Condition (2) */
      && (p->selFlags & SF_OrderByReqd)==0         /* Condition (3) and (4) */
      && (pItem->fg.isCte==0 || pItem->u2.pCteUse->eM10d!=M10d_Yes) /* (6) */
-     && OptimizationEnabled(db, SQLITE_OmitOrderBy)
+     && OptimizationEnabled(db, SQLITE_OmitOrderBy)                /* (7) */
     ){
       TREETRACE(0x800,pParse,p,
                 ("omit superfluous ORDER BY on %r FROM-clause subquery\n",i+1));
@@ -7359,6 +7366,11 @@ int sqlite3Select(
       continue;
     }
 
+    /* Do not flatten a MATERIALIZED CTE */
+    if( pItem->fg.isCte && pItem->u2.pCteUse->eM10d==M10d_Yes ){
+      continue;
+    }
+
     if( flattenSubquery(pParse, p, i, isAgg) ){
       if( pParse->nErr ) goto select_end;
       /* This subquery can be absorbed into its parent. */