Fix a problem with group_concat() when it is used as a window function with

a sliding window, as described by
[forum:/forumpost/f3eb24a6c0|forum thread f3eb24a6c0].

FossilOrigin-Name: f47f7f78227830c065d9ce715b8456eab81a38d680f76bf4ff08f298d84f9c7a

manifest

@@ -1,5 +1,5 @@
-C Fix\sharmless\scompiler\swarnings.
+C Fix\sa\sproblem\swith\sgroup_concat()\swhen\sit\sis\sused\sas\sa\swindow\sfunction\swith\na\ssliding\swindow,\sas\sdescribed\sby\n[forum:/forumpost/f3eb24a6c0|forum\sthread\sf3eb24a6c0].
-D 2021-10-01T21:01:07.786
+D 2021-10-01T22:48:52.993
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -504,7 +504,7 @@ F src/delete.c 3ce6af6b64c8b476de51ccc32da0cb3142d42e65754e1d8118addf65b8bcba15
 F src/expr.c 82797e5d82422d34ede9a95ba459f40c317b2daadb21109a21abfd42f84e3ed8
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c 1905af1821b88321e1bb9d6a69e704495b6844a9b6c29398d40117cc251e893c
-F src/func.c 812ac5383067bed7150d8597e83c47b714d73db0e62af55811d1a145243e58e1
+F src/func.c f4924c04e95335762ed1b24f184df26d0db5b20e87decbc5a0ed6431f7ebd9ca
 F src/global.c 612ea60c9acbcb45754c2ed659b4a56936a06814718e969636fedc7e3b889808
 F src/hash.c 8d7dda241d0ebdafb6ffdeda3149a412d7df75102cecfc1021c98d6219823b19
 F src/hash.h 9d56a9079d523b648774c1784b74b89bd93fac7b365210157482e4319a468f38
@@ -545,7 +545,7 @@ F src/pcache1.c 54881292a9a5db202b2c0ac541c5e3ef9a5e8c4f1c1383adb2601d5499a60e65
 F src/pragma.c 4a473feae3646063996ce3bfae78032009fa950765908d97424f7578b202813c
 F src/pragma.h b33c7a542ae7965c471f0d3c0565ce4d340c3f32cc162f44133539b6b0edb927
 F src/prepare.c 8f07616db04337057b8498b72d051ee90f73c54615c2e908c05404cef1e060b7
-F src/printf.c 78fabb49b9ac9a12dd1c89d744abdc9b67fd3205e62967e158f78b965a29ec4b
+F src/printf.c 1ce574bf02b503b0e031a70d3453324a9f4a0eb1ad379f3324ced73b918ed20b
 F src/random.c 097dc8b31b8fba5a9aca1697aeb9fd82078ec91be734c16bffda620ced7ab83c
 F src/resolve.c b9e60afa56d0484ee573aba54d9e73603736236df33d2ae3421b4cd0367d907d
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
@@ -554,7 +554,7 @@ F src/shell.c.in 928114971b558dc2e40a1afaf07e3e5e93558a77ecca95067c51e1f9d3c1441
 F src/sqlite.h.in 4e977a5e2ed1a9e8987ff65a2cab5f99a4298ebf040ea5ff636e1753339ff45a
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h e97f4e9b509408fea4c4e9bef5a41608dfac343b4d3c7a990dedde1e19af9510
-F src/sqliteInt.h c481cd4864217bdff96fc2a7054cdaca0edabe0eb9f6cce8b012d1e014ccdc5f
+F src/sqliteInt.h 2cfc99065003dd1f5d91a85114449f920fde0adbea4bdbd524fca8907a6e38f3
 F src/sqliteLimit.h d7323ffea5208c6af2734574bae933ca8ed2ab728083caa117c9738581a31657
 F src/status.c 4b8bc2a6905163a38b739854a35b826c737333fab5b1f8e03fa7eb9a4799c4c1
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
@@ -1799,10 +1799,11 @@ F test/window8.tcl 5e02e41d9d9a80f597063aed1a381eb19d1d0ef677a4f0df352c5365cf23f
 F test/window8.test 4ab16817414af0c904abe2ebdf88eb6c2b00058b84f9748c6174ff11fc45f1ed
 F test/window9.test 349c71eab4288a1ffc19e2f65872ec2c37e6cf8a1dda2ad300364b7450ae4836
 F test/windowA.test 6d63dc1260daa17141a55007600581778523a8b420629f1282d2acfc36af23be
-F test/windowB.test 6e601f8178ba8ba28b2f19e74fe613815084bb4a8d2ad942defc7d42e191e521
+F test/windowB.test b67bda5645f3226790e1a360c4225241840b84adb5aa2e69bfb0b27eef3b84d9
+F test/windowC.test ecf1831b995408b03f708386b37ece7a05108faf2288c0c55cff873c100e145f
 F test/windowerr.tcl f5acd6fbc210d7b5546c0e879d157888455cd4a17a1d3f28f07c1c8a387019e0
 F test/windowerr.test a8b752402109c15aa1c5efe1b93ccb0ce1ef84fa964ae1cd6684dd0b3cc1819b
-F test/windowfault.test 21919e601f20b976ea2a73aa401220c89ed0e8d203c4f69476ea55bce3726496
+F test/windowfault.test 15094c1529424e62f798bc679e3fe9dfab6e8ba2f7dfe8c923b6248c31660a7c
 F test/windowpushd.test d8895d08870b7226f7693665bd292eb177e62ca06799184957b3ca7dc03067df
 F test/with1.test 7bc5abfe4c80c0cef8a90f5a66d60b9982e8ccd7350c8eb70611323a3b8e07ba
 F test/with2.test a1df41b987198383b9b70bf5e5fda390582e46398653858dbc6ceb24253b28df
@@ -1928,7 +1929,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 2f7c946c5f25a858167f5193ca06e53310394c8cff15426ab8a1327a1ec835fd
+P 94b59691ee50a4666b25e36d1529fc52f714bbe94c3e8ccb35bf0a4ea11050db 8bd721c29e7a28cd75885dd80235e4e37aa0847229f769f49e01127f794fa63a
-R efed3f9c2718d18bc8a69a58b9e2f371
+R 755a222a3849cf0b99ca8b66d427fd7c
+T +closed 8bd721c29e7a28cd75885dd80235e4e37aa0847229f769f49e01127f794fa63a
 U drh
-Z 00ef577a561ca93dc97c1f48c37c36a1
+Z d91f8598d681fe6b47f22c72a76f272f

manifest.uuid

@@ -1 +1 @@
-94b59691ee50a4666b25e36d1529fc52f714bbe94c3e8ccb35bf0a4ea11050db
+f47f7f78227830c065d9ce715b8456eab81a38d680f76bf4ff08f298d84f9c7a

src/func.c

@@ -1715,97 +1715,172 @@ static void minMaxFinalize(sqlite3_context *context){
 
 /*
 ** group_concat(EXPR, ?SEPARATOR?)
+**
+** The SEPARATOR goes before the EXPR string.  This is tragic.  The
+** groupConcatInverse() implementation would have been easier if the
+** SEPARATOR were appended after EXPR.  And the order is undocumented,
+** so we could change it, in theory.  But the old behavior has been
+** around for so long that we dare not, for fear of breaking something.
 */
+typedef struct {
+  StrAccum str;          /* The accumulated concatenation */
+#ifndef SQLITE_OMIT_WINDOWFUNC
+  int nAccum;            /* Number of strings presently concatenated */
+  int nFirstSepLength;   /* Used to detect separator length change */
+  /* If pnSepLengths!=0, refs an array of inter-string separator lengths,
+  ** stored as actually incorporated into presently accumulated result.
+  ** (Hence, its slots in use number nAccum-1 between method calls.)
+  ** If pnSepLengths==0, nFirstSepLength is the length used throughout.
+  */
+  int *pnSepLengths;
+#endif
+} GroupConcatCtx;
+
 static void groupConcatStep(
   sqlite3_context *context,
   int argc,
   sqlite3_value **argv
 ){
   const char *zVal;
-  StrAccum *pAccum;
+  GroupConcatCtx *pGCC;
   const char *zSep;
   int nVal, nSep;
   assert( argc==1 || argc==2 );
   if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
-  pAccum = (StrAccum*)sqlite3_aggregate_context(context, sizeof(*pAccum));
+  pGCC = (GroupConcatCtx*)sqlite3_aggregate_context(context, sizeof(*pGCC));
-
+  if( pGCC ){
-  if( pAccum ){
     sqlite3 *db = sqlite3_context_db_handle(context);
-    int firstTerm = pAccum->mxAlloc==0;
+    int firstTerm = pGCC->str.mxAlloc==0;
-    pAccum->mxAlloc = db->aLimit[SQLITE_LIMIT_LENGTH];
+    pGCC->str.mxAlloc = db->aLimit[SQLITE_LIMIT_LENGTH];
+    if( argc==1 ){
       if( !firstTerm ){
-      if( argc==2 ){
+        sqlite3_str_appendchar(&pGCC->str, 1, ',');
+      }
+#ifndef SQLITE_OMIT_WINDOWFUNC
+      else{
+        pGCC->nFirstSepLength = 1;
+      }
+#endif
+    }else if( !firstTerm ){
       zSep = (char*)sqlite3_value_text(argv[1]);
       nSep = sqlite3_value_bytes(argv[1]);
+      if( zSep ){
+        sqlite3_str_append(&pGCC->str, zSep, nSep);
+      }
+#ifndef SQLITE_OMIT_WINDOWFUNC
+      else{
+        nSep = 0;
+      }
+      if( nSep != pGCC->nFirstSepLength || pGCC->pnSepLengths != 0 ){
+        int *pnsl = pGCC->pnSepLengths;
+        if( pnsl == 0 ){
+          /* First separator length variation seen, start tracking them. */
+          pnsl = (int*)sqlite3_malloc64((pGCC->nAccum+1) * sizeof(int));
+          if( pnsl!=0 ){
+            int i = 0, nA = pGCC->nAccum-1;
+            while( i<nA ) pnsl[i++] = pGCC->nFirstSepLength;
+          }
         }else{
-        zSep = ",";
+          pnsl = (int*)sqlite3_realloc64(pnsl, pGCC->nAccum * sizeof(int));
-        nSep = 1;
         }
-      if( zSep ) sqlite3_str_append(pAccum, zSep, nSep);
+        if( pnsl!=0 ){
+          if( ALWAYS(pGCC->nAccum>0) ){
+            pnsl[pGCC->nAccum-1] = nSep;
           }
+          pGCC->pnSepLengths = pnsl;
+        }else{
+          sqlite3StrAccumSetError(&pGCC->str, SQLITE_NOMEM);
+        }
+      }
+#endif
+    }
+#ifndef SQLITE_OMIT_WINDOWFUNC
+    else{
+      pGCC->nFirstSepLength = sqlite3_value_bytes(argv[1]);
+    }
+    pGCC->nAccum += 1;
+#endif
     zVal = (char*)sqlite3_value_text(argv[0]);
     nVal = sqlite3_value_bytes(argv[0]);
-    if( zVal ) sqlite3_str_append(pAccum, zVal, nVal);
+    if( zVal ) sqlite3_str_append(&pGCC->str, zVal, nVal);
   }
 }
+
 #ifndef SQLITE_OMIT_WINDOWFUNC
 static void groupConcatInverse(
   sqlite3_context *context,
   int argc,
   sqlite3_value **argv
 ){
-  int n;
+  GroupConcatCtx *pGCC;
-  StrAccum *pAccum;
   assert( argc==1 || argc==2 );
+  (void)argc;  /* Suppress unused parameter warning */
   if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
-  pAccum = (StrAccum*)sqlite3_aggregate_context(context, sizeof(*pAccum));
+  pGCC = (GroupConcatCtx*)sqlite3_aggregate_context(context, sizeof(*pGCC));
-  /* pAccum is always non-NULL since groupConcatStep() will have always
+  /* pGCC is always non-NULL since groupConcatStep() will have always
   ** run frist to initialize it */
-  if( ALWAYS(pAccum) ){
+  if( ALWAYS(pGCC) ){
-    n = sqlite3_value_bytes(argv[0]);
+    int nVS = sqlite3_value_bytes(argv[0]);
-    if( argc==2 ){
+    pGCC->nAccum -= 1;
-      n += sqlite3_value_bytes(argv[1]);
+    if( pGCC->pnSepLengths!=0 ){
-    }else{
+      assert(pGCC->nAccum >= 0);
-      n++;
+      if( pGCC->nAccum>0 ){
+        nVS += *pGCC->pnSepLengths;
+        memmove(pGCC->pnSepLengths, pGCC->pnSepLengths+1,
+               (pGCC->nAccum-1)*sizeof(int));
       }
-    if( n>=(int)pAccum->nChar ){
-      pAccum->nChar = 0;
     }else{
-      pAccum->nChar -= n;
+      /* If removing single accumulated string, harmlessly over-do. */
-      memmove(pAccum->zText, &pAccum->zText[n], pAccum->nChar);
+      nVS += pGCC->nFirstSepLength;
+    }
+    if( nVS>=(int)pGCC->str.nChar ){
+      pGCC->str.nChar = 0;
+    }else{
+      pGCC->str.nChar -= nVS;
+      memmove(pGCC->str.zText, &pGCC->str.zText[nVS], pGCC->str.nChar);
+    }
+    if( pGCC->str.nChar==0 ){
+      pGCC->str.mxAlloc = 0;
+      sqlite3_free(pGCC->pnSepLengths);
+      pGCC->pnSepLengths = 0;
     }
-    if( pAccum->nChar==0 ) pAccum->mxAlloc = 0;
   }
 }
 #else
 # define groupConcatInverse 0
 #endif /* SQLITE_OMIT_WINDOWFUNC */
 static void groupConcatFinalize(sqlite3_context *context){
-  StrAccum *pAccum;
+  GroupConcatCtx *pGCC
-  pAccum = sqlite3_aggregate_context(context, 0);
+    = (GroupConcatCtx*)sqlite3_aggregate_context(context, 0);
-  if( pAccum ){
+  if( pGCC ){
+    StrAccum *pAccum = &pGCC->str;
     if( pAccum->accError==SQLITE_TOOBIG ){
       sqlite3_result_error_toobig(context);
     }else if( pAccum->accError==SQLITE_NOMEM ){
       sqlite3_result_error_nomem(context);
     }else{
-      sqlite3_result_text(context, sqlite3StrAccumFinish(pAccum), -1, 
+      int n = pAccum->nChar;
+      sqlite3_result_text(context, sqlite3StrAccumFinish(pAccum), n, 
                           sqlite3_free);
     }
+#ifndef SQLITE_OMIT_WINDOWFUNC
+    sqlite3_free(pGCC->pnSepLengths);
+#endif
   }
 }
 #ifndef SQLITE_OMIT_WINDOWFUNC
 static void groupConcatValue(sqlite3_context *context){
-  sqlite3_str *pAccum;
+  GroupConcatCtx *pGCC
-  pAccum = (sqlite3_str*)sqlite3_aggregate_context(context, 0);
+    = (GroupConcatCtx*)sqlite3_aggregate_context(context, 0);
-  if( pAccum ){
+  if( pGCC ){
+    StrAccum *pAccum = &pGCC->str;
     if( pAccum->accError==SQLITE_TOOBIG ){
       sqlite3_result_error_toobig(context);
     }else if( pAccum->accError==SQLITE_NOMEM ){
       sqlite3_result_error_nomem(context);
     }else{    
       const char *zText = sqlite3_str_value(pAccum);
-      sqlite3_result_text(context, zText, -1, SQLITE_TRANSIENT);
+      sqlite3_result_text(context, zText, pAccum->nChar, SQLITE_TRANSIENT);
     }
   }
 }

src/printf.c

@@ -145,7 +145,7 @@ static char et_getdigit(LONGDOUBLE_TYPE *val, int *cnt){
 /*
 ** Set the StrAccum object to an error mode.
 */
-static void setStrAccumError(StrAccum *p, u8 eError){
+void sqlite3StrAccumSetError(StrAccum *p, u8 eError){
   assert( eError==SQLITE_NOMEM || eError==SQLITE_TOOBIG );
   p->accError = eError;
   if( p->mxAlloc ) sqlite3_str_reset(p);
@@ -181,12 +181,12 @@ static char *printfTempBuf(sqlite3_str *pAccum, sqlite3_int64 n){
   char *z;
   if( pAccum->accError ) return 0;
   if( n>pAccum->nAlloc && n>pAccum->mxAlloc ){
-    setStrAccumError(pAccum, SQLITE_TOOBIG);
+    sqlite3StrAccumSetError(pAccum, SQLITE_TOOBIG);
     return 0;
   }
   z = sqlite3DbMallocRaw(pAccum->db, n);
   if( z==0 ){
-    setStrAccumError(pAccum, SQLITE_NOMEM);
+    sqlite3StrAccumSetError(pAccum, SQLITE_NOMEM);
   }
   return z;
 }
@@ -925,7 +925,7 @@ static int sqlite3StrAccumEnlarge(StrAccum *p, int N){
     return 0;
   }
   if( p->mxAlloc==0 ){
-    setStrAccumError(p, SQLITE_TOOBIG);
+    sqlite3StrAccumSetError(p, SQLITE_TOOBIG);
     return p->nAlloc - p->nChar - 1;
   }else{
     char *zOld = isMalloced(p) ? p->zText : 0;
@@ -938,7 +938,7 @@ static int sqlite3StrAccumEnlarge(StrAccum *p, int N){
     }
     if( szNew > p->mxAlloc ){
       sqlite3_str_reset(p);
-      setStrAccumError(p, SQLITE_TOOBIG);
+      sqlite3StrAccumSetError(p, SQLITE_TOOBIG);
       return 0;
     }else{
       p->nAlloc = (int)szNew;
@@ -956,7 +956,7 @@ static int sqlite3StrAccumEnlarge(StrAccum *p, int N){
       p->printfFlags |= SQLITE_PRINTF_MALLOCED;
     }else{
       sqlite3_str_reset(p);
-      setStrAccumError(p, SQLITE_NOMEM);
+      sqlite3StrAccumSetError(p, SQLITE_NOMEM);
       return 0;
     }
   }
@@ -1029,7 +1029,7 @@ static SQLITE_NOINLINE char *strAccumFinishRealloc(StrAccum *p){
     memcpy(zText, p->zText, p->nChar+1);
     p->printfFlags |= SQLITE_PRINTF_MALLOCED;
   }else{
-    setStrAccumError(p, SQLITE_NOMEM);
+    sqlite3StrAccumSetError(p, SQLITE_NOMEM);
   }
   p->zText = zText;
   return zText;

src/sqliteInt.h

@@ -4940,6 +4940,7 @@ int sqlite3OpenTempDatabase(Parse *);
 
 void sqlite3StrAccumInit(StrAccum*, sqlite3*, char*, int, int);
 char *sqlite3StrAccumFinish(StrAccum*);
+void sqlite3StrAccumSetError(StrAccum*, u8);
 void sqlite3SelectDestInit(SelectDest*,int,int);
 Expr *sqlite3CreateColumnExpr(sqlite3 *, SrcList *, int, int);
 

test/windowB.test

@@ -9,6 +9,7 @@
 #
 #***********************************************************************
 # Test cases for RANGE BETWEEN and especially with NULLS LAST
+# and for varying separator handling by group_concat().
 #
 
 set testdir [file dirname $argv0]
@@ -356,5 +357,12 @@ do_execsql_test 8.1 {
   FROM t1;
 } {111 660 938 979}
 
+do_execsql_test 9.0 {
+  CREATE TABLE seps(x);
+  INSERT INTO seps(x) VALUES ('1'), ('22'), ('333'), ('4444');
+  SELECT group_concat('-', x)
+    OVER ( ORDER BY x ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING )
+  FROM seps;
+} {-22- -22-333- -333-4444- -4444-}
 
 finish_test

test/windowC.test

@@ -0,0 +1,66 @@
+# 2021-09-29
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# Test cases for varying separator handling by group_concat().
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+set testprefix windowB
+
+ifcapable !windowfunc {
+  finish_test
+  return
+}
+
+do_execsql_test 1.0 {
+  CREATE TABLE x1(i INTEGER PRIMARY KEY, x);
+}
+
+foreach {tn bBlob seps} {
+  1 0 {a b c def g}
+  2 0 {abcdefg {} {} abcdefg}
+  3 0 {a bc def ghij klmno pqrstu}
+  4 1 {a bc def ghij klmno pqrstu}
+  5 1 {, , , , , , , , , , , , ....... , ,}
+} {
+  foreach type {text blob} {
+    do_test 1.$type.$tn.1 {
+      execsql { DELETE FROM x1 }
+      foreach s $seps {
+        if {$type=="text"} {
+          execsql {INSERT INTO x1 VALUES(NULL, $s)}
+        } else {
+          execsql {INSERT INTO x1 VALUES(NULL, CAST ($s AS blob))}
+        }
+      }
+    } {}
+
+    foreach {tn2 win} {
+      1     "ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING"
+      2     "ROWS BETWEEN 2 PRECEDING AND CURRENT ROW"
+      3     "ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING"
+    } {
+      do_test 1.$type.$tn.2.$tn2 {
+        db eval "
+          SELECT group_concat('val', x) OVER ( ORDER BY i $win ) AS val FROM x1
+          " {
+            if {[string range $val 0 2]!="val"
+              || [string range $val end-2 end]!="val"
+            } {
+              error "unexpected return value: $val"
+            }
+          }
+      } {} 
+    }
+  }
+}
+
+finish_test

test/windowfault.test

@@ -292,4 +292,43 @@ do_faultsim_test 12 -faults oom* -prep {
   faultsim_test_result {0 {}}
 }
 
+#-------------------------------------------------------------------------
+reset_db
+do_execsql_test 13.0 {
+  CREATE TABLE t1(id INTEGER PRIMARY KEY, a, b);
+  INSERT INTO t1 VALUES(1, '1', 'a');
+  INSERT INTO t1 VALUES(2, '22', 'b');
+  INSERT INTO t1 VALUES(3, '333', 'c');
+  INSERT INTO t1 VALUES(4, '4444', 'dddd');
+  INSERT INTO t1 VALUES(5, '55555', 'e');
+  INSERT INTO t1 VALUES(6, '666666', 'f');
+  INSERT INTO t1 VALUES(7, '7777777', 'gggggggggg');
+} {}
+
+set queryres [list {*}{
+  1b22
+  1b22c333
+  22c333dddd4444 
+  333dddd4444e55555 
+  4444e55555f666666
+  55555f666666gggggggggg7777777 
+  666666gggggggggg7777777
+}]
+do_execsql_test 13.1 {
+  SELECT group_concat(a, b) OVER (
+    ORDER BY id RANGE BETWEEN 1 PRECEDING AND 1 FOLLOWING
+  ) FROM t1
+} $queryres
+
+do_faultsim_test 13 -faults oom* -prep {
+} -body {
+  execsql {
+    SELECT group_concat(a, b) OVER (
+        ORDER BY id RANGE BETWEEN 1 PRECEDING AND 1 FOLLOWING
+    ) FROM t1
+  }
+} -test {
+  faultsim_test_result [list 0 $::queryres]
+}
+
 finish_test