Do not disable unused columns in a UNION ALL sub-query if any component of the sub-query is DISTINCT.

FossilOrigin-Name: c84d5602ac9bfb4f12c3cf62033af616e51913c26877d1a0761363a625295f53

manifest

@@ -1,5 +1,5 @@
-C Fix\sa\sbug\sin\sjson_array_length()\sintroduced\sin\sversion\s3.43.0\sby\ncheck-in\s[df099ad713011b67].\s\sIf\sthe\sJSON\sinput\scomes\sfrom\sjson_remove(),\nthe\sremoved\sarray\sentries\sare\sstill\scounted\sas\spart\sof\sthe\sarray\slength.
-D 2023-08-30T18:19:40.630
+C Do\snot\sdisable\sunused\scolumns\sin\sa\sUNION\sALL\ssub-query\sif\sany\scomponent\sof\sthe\ssub-query\sis\sDISTINCT.
+D 2023-08-31T18:00:10.037
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -705,7 +705,7 @@ F src/printf.c e3ba080e2f409f9bfcc8d34724e6fc160e9c718dc92d0548f6b71b8b6f860ce2
 F src/random.c 606b00941a1d7dd09c381d3279a058d771f406c5213c9932bbd93d5587be4b9c
 F src/resolve.c 37953a5f36c60bea413c3c04efcd433b6177009f508ef2ace0494728912fe2e9
 F src/rowset.c 8432130e6c344b3401a8874c3cb49fefe6873fec593294de077afea2dce5ec97
-F src/select.c 5f545a2c8702d4d3430bbb188cfec47d6c122d899061ef00cbe56af14591c574
+F src/select.c e9fb48546ab1882639a3a960383f6342dddb776c0227615f8e19de51f0102f68
 F src/shell.c.in 2f9be25294b68b07e7e81f0adcec4475aba6011b64f160e414efe226910c4d7b
 F src/sqlite.h.in 73a366c1c45d5ac9888cfe81c458826a44498531d106cfb4f328193ab5f6f17d
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
@@ -1524,7 +1524,7 @@ F test/selectD.test 6d1909b49970bf92f45ce657505befcef5fc7cbc13544e18103a316d3218
 F test/selectE.test a8730ca330fcf40ace158f134f4fe0eb00c7edbf
 F test/selectF.test 21c94e6438f76537b72532fa9fd4710cdd455fc3
 F test/selectG.test 089f7d3d7e6db91566f00b036cb353107a2cca6220eb1cb264085a836dae8840
-F test/selectH.test 88237ded5925adfb3f27fdafb5428c2ffc4d61e313bceb854e225ffc3ef0d206
+F test/selectH.test 0b54599f1917d99568c9b929df22ec6261ed7b6d2f02a46b5945ef81b7871aac
 F test/session.test 78fa2365e93d3663a6e933f86e7afc395adf18be
 F test/sessionfuzz-data1.db 1f8d5def831f19b1c74571037f0d53a588ea49a6c4ca2a028fc0c27ef896dbcb
 F test/sessionfuzz.c 5eef09af01eeff6f20250ae4c0112c2e576e4d2f2026cc9a49dc5be6886fa6ee
@@ -2115,8 +2115,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 6df6f17ccb404c648076ccff4200d0eb5437f0e3e82424bf3da5ea682b107bb4
-R a6b4813d874e48e33979a0a866fb60f7
-U drh
-Z 576d8a059991479143ca23bbfdab41fe
+P 69a635958a4a14187e88dd297df8978a4805b1b0c7bff3ec29d5632c0f68d889
+R d2f762ea2bd6c854c7390f15c4dca4b3
+U dan
+Z fa3e59f3f8f5f13ff2286fb3bd2052e6
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-69a635958a4a14187e88dd297df8978a4805b1b0c7bff3ec29d5632c0f68d889
+c84d5602ac9bfb4f12c3cf62033af616e51913c26877d1a0761363a625295f53

src/select.c

@@ -5301,12 +5301,12 @@ static int disableUnusedSubqueryResultColumns(SrcItem *pItem){
   assert( pItem->pSelect!=0 );
   pSub = pItem->pSelect;
   assert( pSub->pEList->nExpr==pTab->nCol );
-  if( (pSub->selFlags & (SF_Distinct|SF_Aggregate))!=0 ){
-    testcase( pSub->selFlags & SF_Distinct );
-    testcase( pSub->selFlags & SF_Aggregate );
-    return 0;
-  }
   for(pX=pSub; pX; pX=pX->pPrior){
+    if( (pX->selFlags & (SF_Distinct|SF_Aggregate))!=0 ){
+      testcase( pX->selFlags & SF_Distinct );
+      testcase( pX->selFlags & SF_Aggregate );
+      return 0;
+    }
     if( pX->pPrior && pX->op!=TK_ALL ){
       /* This optimization does not work for compound subqueries that
       ** use UNION, INTERSECT, or EXCEPT.  Only UNION ALL is allowed. */

test/selectH.test

@@ -113,6 +113,33 @@ do_execsql_test 4.1 {
   CREATE TABLE t1(a INTEGER PRIMARY KEY, b TEXT);
   SELECT 1 FROM (SELECT DISTINCT name COLLATE rtrim FROM sqlite_schema
                  UNION ALL SELECT a FROM t1);
-} 1
+} {1 1}
+
+do_execsql_test 4.2 {
+  SELECT DISTINCT name COLLATE rtrim FROM sqlite_schema 
+    UNION ALL 
+  SELECT a FROM t1
+} {v1 t1}
+
+#-------------------------------------------------------------------------
+# forum post https://sqlite.org/forum/forumpost/b83c7b2168
+#
+reset_db
+do_execsql_test 5.0 {
+  CREATE TABLE t1 (val1);
+  INSERT INTO t1 VALUES(4);
+  INSERT INTO t1 VALUES(5);
+  CREATE TABLE t2 (val2);
+}
+do_execsql_test 5.1 {
+  SELECT DISTINCT val1 FROM t1 UNION ALL SELECT val2 FROM t2;
+} {
+  4 5
+}
+do_execsql_test 5.2 {
+  SELECT count(1234) FROM (
+    SELECT DISTINCT val1 FROM t1 UNION ALL SELECT val2 FROM t2
+  )
+} {2}
 
 finish_test