Fix the OP_OpenEphemeral opcode in the bytecode engine so that if it is called

a second or subsequent time, it merely clears the existing table rather than
creating a new one.  Proposed fix for ticket [d0866b26f83e9c55e30de0821f5d].

FossilOrigin-Name: 4678cb1044f0b4dc813e48f3bd0f85240a66e2ecf8763280d66726cc031c93a7

manifest

@@ -1,5 +1,5 @@
-C Additional\ssmall\sperformance\sincrease\sand\ssize\sreduction\sto\sthe\nsqlite3VdbeMakeLabel()\smechanism.
-D 2018-12-29T14:23:22.316
+C Fix\sthe\sOP_OpenEphemeral\sopcode\sin\sthe\sbytecode\sengine\sso\sthat\sif\sit\sis\scalled\na\ssecond\sor\ssubsequent\stime,\sit\smerely\sclears\sthe\sexisting\stable\srather\sthan\ncreating\sa\snew\sone.\s\sProposed\sfix\sfor\sticket\s[d0866b26f83e9c55e30de0821f5d].
+D 2018-12-31T16:36:42.338
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in d8b254f8bb81bab43c340d70d17dc3babab40fcc8a348c8255881f780a45fee6
@@ -581,7 +581,7 @@ F src/upsert.c 0dd81b40206841814d46942a7337786932475f085716042d0cb2fc7791bf8ca4
 F src/utf.c 810fbfebe12359f10bc2a011520a6e10879ab2a163bcb26c74768eab82ea62a5
 F src/util.c d9eb0a6c4aae1b00a7369eadd7ca0bbe946cb4c953b6751aa20d357c2f482157
 F src/vacuum.c 3ffe64ecfc94b7528c5d7bdb1c3a19d72fec63f2aa846e3b90f8de5dbbddf5aa
-F src/vdbe.c 8869a60f4b910c0f6d4ae0f0e23b7a835cae7ed67aa0ce2053d1bbe3e9facc53
+F src/vdbe.c 0321eb484160353d48accd3e67e06191173c6caa5f9995314021159017a5678b
 F src/vdbe.h b61a6f4f23ca4f5e789f4fc9d55acd4570d50d3288457651e501d839f5167c1f
 F src/vdbeInt.h a76d5eed62c76bcd8de7afd3147fac1bc40c5a870582664bcd7d071ef437c37f
 F src/vdbeapi.c 57a2d794a8833f269b878dbc24e955369bdb379af6c4e93ebc5ce1a20fa3daf4
@@ -1666,7 +1666,7 @@ F test/win32heap.test 10fd891266bd00af68671e702317726375e5407561d859be1aa04696f2
 F test/win32lock.test fbf107c91d8f5512be5a5b87c4c42ab9fdd54972
 F test/win32longpath.test 169c75a3b2e43481f4a62122510210c67b08f26d
 F test/win32nolock.test ac4f08811a562e45a5755e661f45ca85892bdbbc
-F test/window1.test a96a80bd6c5cc0e4bacbd3948223604e4b2745e37909a70d09c05f5ef6f84266
+F test/window1.test 148552f6331a1b9fbdc034ee1b46233cf52b58b98936ca2e74c9d5eba653b2ba
 F test/window2.tcl 9bfa842d8a62b0d36dc8c1b5972206393c43847433c6d75940b87fec93ce3143
 F test/window2.test 8e6d2a1b9f54dfebee1cde961c8590cd87b4db45c50f44947a211e1b63c2a05e
 F test/window3.tcl 577a3b1ff913208e5248c04dab9df17fd760ce159a752789e26d0cb4a5f91823
@@ -1795,7 +1795,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 4a0929ac76d8aa5dd65eac3b83d6bbf41e505e01d175ca0fb2b19ba02d439415
-R 03e098302f2e99c4f7d3aaa87549bd2b
+P 1bdee199a71e0a6c247b85e72de9e3a3099b7179c33288735721facef3b96459
+R 2a9dff6dec1fd031ba98ddeee634566f
 U drh
-Z c77cecf32a6a6d57b97fc21a20b9218b
+Z f80234c4b191a7b9e8e4e0c806044597

manifest.uuid

@@ -1 +1 @@
-1bdee199a71e0a6c247b85e72de9e3a3099b7179c33288735721facef3b96459
+4678cb1044f0b4dc813e48f3bd0f85240a66e2ecf8763280d66726cc031c93a7

src/vdbe.c

@@ -3628,6 +3628,9 @@ case OP_OpenDup: {
 ** the main database is read-only.  The ephemeral
 ** table is deleted automatically when the cursor is closed.
 **
+** If the cursor P1 is already opened on an ephermal table, the table
+** is cleared (all content is erased).
+**
 ** P2 is the number of columns in the ephemeral table.
 ** The cursor points to a BTree table if P4==0 and to a BTree index
 ** if P4 is not 0.  If P4 is not NULL, it points to a KeyInfo structure
@@ -3659,6 +3662,14 @@ case OP_OpenEphemeral: {
       SQLITE_OPEN_TRANSIENT_DB;
   assert( pOp->p1>=0 );
   assert( pOp->p2>=0 );
+  pCx = p->apCsr[pOp->p1];
+  if( pCx ){
+    /* If the ephermeral table is already open, erase all existing content
+    ** so that the table is empty again, rather than creating a new table. */
+    rc = sqlite3BtreeClearTable(pCx->pBtx, pCx->pgnoRoot, 0);
+    if( rc ) goto abort_due_to_error;
+    break;
+  }
   pCx = allocateCursor(p, pOp->p1, pOp->p2, -1, CURTYPE_BTREE);
   if( pCx==0 ) goto no_mem;
   pCx->nullRow = 1;
@@ -3675,18 +3686,19 @@ case OP_OpenEphemeral: {
     ** automatically created table with root-page 1 (an BLOB_INTKEY table).
     */
     if( (pCx->pKeyInfo = pKeyInfo = pOp->p4.pKeyInfo)!=0 ){
-      int pgno;
       assert( pOp->p4type==P4_KEYINFO );
-      rc = sqlite3BtreeCreateTable(pCx->pBtx, &pgno, BTREE_BLOBKEY | pOp->p5); 
+      rc = sqlite3BtreeCreateTable(pCx->pBtx, (int*)&pCx->pgnoRoot,
+                                   BTREE_BLOBKEY | pOp->p5); 
       if( rc==SQLITE_OK ){
-        assert( pgno==MASTER_ROOT+1 );
+        assert( pCx->pgnoRoot==MASTER_ROOT+1 );
         assert( pKeyInfo->db==db );
         assert( pKeyInfo->enc==ENC(db) );
-        rc = sqlite3BtreeCursor(pCx->pBtx, pgno, BTREE_WRCSR,
+        rc = sqlite3BtreeCursor(pCx->pBtx, pCx->pgnoRoot, BTREE_WRCSR,
                                 pKeyInfo, pCx->uc.pCursor);
       }
       pCx->isTable = 0;
     }else{
+      pCx->pgnoRoot = MASTER_ROOT;
       rc = sqlite3BtreeCursor(pCx->pBtx, MASTER_ROOT, BTREE_WRCSR,
                               0, pCx->uc.pCursor);
       pCx->isTable = 1;

test/window1.test

@@ -620,4 +620,49 @@ do_execsql_test 14.1 {
   );
 } {1 2 3}
 
+# 2018-12-31
+# https://www.sqlite.org/src/info/d0866b26f83e9c55
+# Window function in correlated subquery causes assertion fault 
+#
+do_catchsql_test 15.0 {
+  WITH t(id, parent) AS (
+  SELECT CAST(1 AS INT), CAST(NULL AS INT)
+  UNION ALL
+  SELECT 2, NULL
+  UNION ALL
+  SELECT 3, 1
+  UNION ALL
+  SELECT 4, 1
+  UNION ALL
+  SELECT 5, 2
+  UNION ALL
+  SELECT 6, 2
+  ), q AS (
+  SELECT t.*, ROW_NUMBER() OVER (ORDER BY t.id) AS rn
+    FROM t
+   WHERE parent IS NULL
+   UNION ALL
+  SELECT t.*, ROW_NUMBER() OVER (ORDER BY t.id) AS rn
+    FROM q
+    JOIN t
+      ON t.parent = q.id
+  )
+  SELECT *
+    FROM q;
+} {1 {cannot use window functions in recursive queries}}
+do_execsql_test 15.1 {
+  DROP TABLE IF EXISTS t1;
+  DROP TABLE IF EXISTS t2;
+  CREATE TABLE t1(x);
+  INSERT INTO t1 VALUES('a'), ('b'), ('c');
+  CREATE TABLE t2(a, b);
+  INSERT INTO t2 VALUES('X', 1), ('X', 2), ('Y', 2), ('Y', 3);
+  SELECT x, (
+    SELECT sum(b)
+      OVER (PARTITION BY a ROWS BETWEEN UNBOUNDED PRECEDING
+                                    AND UNBOUNDED FOLLOWING)
+    FROM t2 WHERE b<x
+  ) FROM t1;
+} {a 3 b 3 c 3}
+
 finish_test