diff --git a/manifest b/manifest
index edd28753b3..19da831492 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Minor\sfix\sto\sthe\sORDER\sBY\selimination\slogic\sin\sgenerate_series().
-D 2021-12-14T18:11:46.057
+C Enhance\sthe\svirtual\stable\squery\splanner\sso\sthat\sit\sis\sable\sto\sdeal\swith\nORDER\sBY\sterms\sthat\scontain\sCOLLATE\sclauses\sas\slong\sas\sthe\sspecified\ncollation\smatches\sthe\svirtual\stable.\s\sThis\sis\sespecially\simportant\sfor\nUNION\sALL\ssince\sa\s"COLLATE\sbinary"\sis\sadded\sto\sORDER\sBY\sclauses\sif\sno\nCOLLATE\sclause\sexists\sin\sthe\soriginal\sSQL.
+D 2021-12-14T20:13:28.303
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -638,7 +638,7 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c ed0398a7adf02c31e34aada42cc86c58f413a7afe5f741a5d373ad087abde028
 F src/wal.h c3aa7825bfa2fe0d85bef2db94655f99870a285778baa36307c0a16da32b226a
 F src/walker.c f890a3298418d7cba3b69b8803594fdc484ea241206a8dfa99db6dd36f8cbb3b
-F src/where.c c3299a18bb95a0189629aaad1207e2214251181e4c71763c2c0a2575a5e4a4c2
+F src/where.c c69fed81e5dfd38e261e9af8c3faba133434b233757b0b2814db71eba86a0a62
 F src/whereInt.h e83f7ba73db5b1b2685118fad67d178fbe04751a25419f0f6ff73e58b4807325
 F src/wherecode.c 6a594ed25bfbeb60d455868b7be62637575e4f1949152de4336e4825e0c54ba6
 F src/whereexpr.c 791544603b254cf11f8e84e3b50b0863c57322e9f213b828680f658e232ebc57
@@ -1453,7 +1453,7 @@ F test/sync.test 89539f4973c010eda5638407e71ca7fddbcd8e0594f4c9980229f804d433309
 F test/sync2.test 8f9f7d4f6d5be8ca8941a8dadcc4299e558cb6a1ff653a9469146c7a76ef2039
 F test/syscall.test a39d9a36f852ae6e4800f861bc2f2e83f68bbc2112d9399931ecfadeabd2d69d
 F test/sysfault.test c9f2b0d8d677558f74de750c75e12a5454719d04
-F test/tabfunc01.test 2708073a405ee3989cfc87a9ee47b2f231b8996529b48ba111ed15fa9106d22c
+F test/tabfunc01.test 241425ce3998687ab24adba09cb95e8012e17499b84a0ed47e128ab45e588bef
 F test/table.test eb3463b7add9f16a5bb836badf118cf391b809d09fdccd1f79684600d07ec132
 F test/tableapi.test ecbcc29c4ab62c1912c3717c48ea5c5e59f7d64e4a91034e6148bd2b82f177f4
 F test/tableopts.test dba698ba97251017b7c80d738c198d39ab747930
@@ -1934,7 +1934,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 788e79f881d443fc1b3a213a7ba4f19bfd245e96c15bb21fcb6bffd92c4320b8
-R 842bfdb0c978a51950e5dd7fb39c0333
+P a2e50712fca9dff1b8d19631f792270c82da3c8696a5d9890cf0d1e13e950d60
+R 1e0532988fdf8f21a62bc70005049044
 U drh
-Z d877d022570b657f3f70fd02d0845d09
+Z 0d6fc2fca37175245191cba6d8527f4e
diff --git a/manifest.uuid b/manifest.uuid
index fd6e39c5d8..17670695af 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-a2e50712fca9dff1b8d19631f792270c82da3c8696a5d9890cf0d1e13e950d60
\ No newline at end of file
+5c3d398d20b86a1558720e995eddf11403aec2d160590571fa9525fe8f6efff9
\ No newline at end of file
diff --git a/src/where.c b/src/where.c
index 982685738a..33e0e43a4c 100644
--- a/src/where.c
+++ b/src/where.c
@@ -1114,6 +1114,10 @@ static sqlite3_index_info *allocateIndexInfo(
   sqlite3_index_info *pIdxInfo;
   u16 mNoOmit = 0;
 
+  assert( pSrc!=0 );
+  assert( pSrc->pTab!=0 );
+  assert( IsVirtual(pSrc->pTab) );
+
   /* Count the number of possible WHERE clause constraints referring
   ** to this virtual table */
   for(i=nTerm=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
@@ -1140,8 +1144,36 @@ static sqlite3_index_info *allocateIndexInfo(
     int n = pOrderBy->nExpr;
     for(i=0; i<n; i++){
       Expr *pExpr = pOrderBy->a[i].pExpr;
-      if( pExpr->op!=TK_COLUMN || pExpr->iTable!=pSrc->iCursor ) break;
+      Expr *pE2;
+
+      /* Virtual tables are unable to deal with NULLS FIRST */
       if( pOrderBy->a[i].sortFlags & KEYINFO_ORDER_BIGNULL ) break;
+
+      /* First case - a direct column references without a COLLATE operator */
+      if( pExpr->op==TK_COLUMN && pExpr->iTable==pSrc->iCursor ){
+        assert( pExpr->iColumn>=XN_ROWID && pExpr->iColumn<pSrc->pTab->nCol );
+        continue;
+      }
+
+      /* 2nd case - a column reference with a COLLATE operator.  Only match
+      ** of the COLLATE operator matches the collation of the column. */
+      if( pExpr->op==TK_COLLATE
+       && (pE2 = pExpr->pLeft)->op==TK_COLUMN
+       && pE2->iTable==pSrc->iCursor
+      ){
+        const char *zColl;  /* The collating sequence name */
+        assert( !ExprHasProperty(pExpr, EP_IntValue) );
+        assert( pExpr->u.zToken!=0 );
+        assert( pE2->iColumn>=XN_ROWID && pE2->iColumn<pSrc->pTab->nCol );
+        pExpr->iColumn = pE2->iColumn;
+        if( pE2->iColumn<0 ) continue;  /* Collseq does not matter for rowid */
+        zColl = sqlite3ColumnColl(&pSrc->pTab->aCol[pE2->iColumn]);
+        if( zColl==0 ) zColl = sqlite3StrBINARY;
+        if( sqlite3_stricmp(pExpr->u.zToken, zColl)==0 ) continue;
+      }
+
+      /* No matches cause a break out of the loop */
+      break;
     }
     if( i==n){
       nOrderBy = n;
@@ -1228,6 +1260,9 @@ static sqlite3_index_info *allocateIndexInfo(
   pIdxInfo->nConstraint = j;
   for(i=0; i<nOrderBy; i++){
     Expr *pExpr = pOrderBy->a[i].pExpr;
+    assert( pExpr->op==TK_COLUMN
+         || (pExpr->op==TK_COLLATE && pExpr->pLeft->op==TK_COLUMN
+              && pExpr->iColumn==pExpr->pLeft->iColumn) );
     pIdxOrderBy[i].iColumn = pExpr->iColumn;
     pIdxOrderBy[i].desc = pOrderBy->a[i].sortFlags & KEYINFO_ORDER_DESC;
   }
diff --git a/test/tabfunc01.test b/test/tabfunc01.test
index 1d990efc4a..0a7e3bc245 100644
--- a/test/tabfunc01.test
+++ b/test/tabfunc01.test
@@ -145,6 +145,23 @@ do_eqp_test tabfunc01-3.13 {
 }
 
 
+do_eqp_test tabfunc01-3.20 {
+  WITH t1(a) AS (
+    SELECT value FROM generate_series(0,10,2)
+    UNION ALL
+    SELECT value FROM generate_series(9,18,3)
+  )
+  SELECT * FROM t1 ORDER BY a;
+} {
+  QUERY PLAN
+  `--MERGE (UNION ALL)
+     |--LEFT
+     |  `--SCAN generate_series VIRTUAL TABLE INDEX 23:
+     `--RIGHT
+        `--SCAN generate_series VIRTUAL TABLE INDEX 23:
+}
+  
+
 # Eponymous virtual table exists in all schemas.
 #
 do_execsql_test tabfunc01-4.1 {