Avoid an OP_Next in cases where an IN(...) query against a UNIQUE index may return at most 1 row.

FossilOrigin-Name: 560f64157d2fe40e107582eebb6526185c9c43305e364f4132e182dbec5b210a

manifest

@@ -1,5 +1,5 @@
-C Avoid\s32-bit\soverflow\swhen\scalculating\sncycle\sfor\s".scanstats\svm".
-D 2024-04-30T19:34:15.474
+C Avoid\san\sOP_Next\sin\scases\swhere\san\sIN(...)\squery\sagainst\sa\sUNIQUE\sindex\smay\sreturn\sat\smost\s1\srow.
+D 2024-05-01T19:48:24.190
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -838,7 +838,7 @@ F src/wal.h ba252daaa94f889f4b2c17c027e823d9be47ce39da1d3799886bbd51f0490452
 F src/walker.c 7c7ea0115345851c3da4e04e2e239a29983b61fb5b038b94eede6aba462640e2
 F src/where.c 0ef9638651b900d64d7e1e877af37cd7900159ff875547ec29b918a1497e5c9c
 F src/whereInt.h 82a13766f13d1a53b05387c2e60726289ef26404bc7b9b1f7770204d97357fb8
-F src/wherecode.c 1f6940349e92a6e056aecd70163b00f331554c815c362b4cc80906c48151d73d
+F src/wherecode.c b73b5bcd0840491e8faa126fbf933e3bda0d9bf85222ddc7ff608154f0f86d1e
 F src/whereexpr.c 67d15caf88a1a9528283d68ff578e024cf9fe810b517bb0343e5aaf695ad97dd
 F src/window.c 5d95122dd330bfaebd732358c8ef067c5a9394a53ac249470d611d0ce2c52be2
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
@@ -1278,6 +1278,7 @@ F test/in3.test 3cbf58c87f4052cee3a58b37b6389777505aa0c0
 F test/in4.test bb767ec1cfd1730256f0a83219f0acda36bc251b63f8b8bb7d8c7cff17875a4f
 F test/in5.test 4fd79c70dfa0681313e8cdca07f5ff0400bdc0e20f808a5c59eaef1e4b48082a
 F test/in6.test f5f40d6816a8bb7c784424b58a10ac38efb76ab29127a2c17399e0cbeeda0e4b
+F test/in7.test e0b3bd735c13547f038f386440152ad2642a066e9f96366552763bb5455117d0
 F test/incrblob.test c9b96afc292aeff43d6687bcb09b0280aa599822
 F test/incrblob2.test a494c9e848560039a23974b9119cfc2cf3ad3bd15cc2694ee6367ae537ef8f1f
 F test/incrblob3.test 67621a04b3084113bf38ce03797d70eca012d9d8f948193b8f655df577b0da6f
@@ -2186,8 +2187,11 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 5f6c079d847e3664ec5acaf1b3e989efe0d548c211ae4a18936162b36df89065
-R 903fbc18fbeeda59fd5e86360c55f235
+P 2858efa06d4fc7b412b892f35f5e9a766b467b4a5b74d602a030d25443f9efb4
+R 5dedafa0dd1df259fa093801bd417269
+T *branch * unique-in-opt
+T *sym-unique-in-opt *
+T -sym-trunk *
 U dan
-Z 0ade4d9c1bbdd68ad336341e8aad91d0
+Z 057540a67356c4bc1a4b77adc8c49f86
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-2858efa06d4fc7b412b892f35f5e9a766b467b4a5b74d602a030d25443f9efb4
+560f64157d2fe40e107582eebb6526185c9c43305e364f4132e182dbec5b210a

src/wherecode.c

@@ -1337,6 +1337,27 @@ static SQLITE_NOINLINE void filterPullDown(
   }
 }
 
+/*
+** Loop pLoop is a WHERE_INDEXED level that uses at least one IN(...) 
+** operator. Return true if level pLoop is guaranteed to visit only one 
+** row for each key generated for the index.
+*/
+static int whereLoopIsOneRow(WhereLoop *pLoop){
+  if( pLoop->u.btree.pIndex->onError 
+   && pLoop->nSkip==0 
+   && pLoop->u.btree.nEq==pLoop->u.btree.pIndex->nKeyCol 
+  ){
+    int ii;
+    for(ii=0; ii<pLoop->u.btree.nEq; ii++){
+      if( pLoop->aLTerm[ii]->eOperator & (WO_IS|WO_ISNULL) ){
+        return 0;
+      }
+    }
+    return 1;
+  }
+  return 0;
+}
+
 /*
 ** Generate code for the start of the iLevel-th loop in the WHERE clause
 ** implementation described by pWInfo.
@@ -2084,7 +2105,9 @@ Bitmask sqlite3WhereCodeOneLoopStart(
     }
  
     /* Record the instruction used to terminate the loop. */
-    if( pLoop->wsFlags & WHERE_ONEROW ){
+    if( (pLoop->wsFlags & WHERE_ONEROW)
+     || (pLevel->u.in.nIn && whereLoopIsOneRow(pLoop))
+    ){
       pLevel->op = OP_Noop;
     }else if( bRev ){
       pLevel->op = OP_Prev;

test/in7.test

@@ -0,0 +1,107 @@
+# 2024-05-01
+#
+# 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.
+#
+#***********************************************************************
+#
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+set testprefix in7
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(a, b, c PRIMARY KEY);
+  CREATE TABLE t2(x, y, z);
+}
+
+foreach {tn nNext idx sql} {
+  1 1 {
+    CREATE INDEX i1 ON t1(a, b);
+  } {
+    SELECT * FROM t1 WHERE (a, b) IN (SELECT x, y FROM t2)
+  } 
+
+  2 0 {
+    CREATE UNIQUE INDEX i1 ON t1(a, b);
+  } {
+    SELECT * FROM t1 WHERE (a, b) IN (SELECT x, y FROM t2)
+  } 
+
+  3 0 {
+    CREATE UNIQUE INDEX i1 ON t1(a, b);
+  } {
+    SELECT * FROM t1 WHERE a = ? AND b = ?
+  } 
+
+  3 1 {
+    CREATE UNIQUE INDEX i1 ON t1(a, b);
+  } {
+    SELECT * FROM t1 WHERE a = ? AND b IS ?
+  } 
+
+  4 0 {
+    CREATE UNIQUE INDEX i1 ON t1(a, b);
+  } {
+    SELECT * FROM t1 WHERE a = ? AND b IN (?, ?, ?);
+  } 
+
+  5 1 {
+    CREATE UNIQUE INDEX i1 ON t1(a, b, c);
+  } {
+    SELECT * FROM t1 WHERE a = ? AND b = ?
+  } 
+
+  6 0 {
+  } {
+    SELECT * FROM t1 WHERE c IN (SELECT z FROM t2)
+  } 
+
+  7 0 {
+  } {
+    SELECT * FROM t1 WHERE (a, c) IN (SELECT z, x FROM t2)
+  } 
+
+  8 1 {
+  } {
+    SELECT * FROM t1 WHERE a IN (SELECT z FROM t2)
+  } 
+} {
+  do_test 1.1.$tn {
+    execsql BEGIN
+    execsql $idx
+
+    catch { array unset root_to_tbl }
+    catch { array unset csr_to_root }
+
+    db eval {SELECT rootpage, tbl_name FROM sqlite_schema} {
+      set root_to_tbl($rootpage) $tbl_name
+    }
+
+    set nSeen 0
+    db eval "explain $sql" {
+      if {$opcode=="OpenRead"} {
+        set csr_to_root($p1) $p2
+      }
+      if {$opcode=="Next"} {
+        catch {
+          set root $csr_to_root($p1)
+          set tbl $root_to_tbl($root)
+          if {$tbl=="t1"} {incr nSeen}
+        }
+      }
+    }
+
+    execsql ROLLBACK
+
+    set nSeen
+  } $nNext
+}
+
+
+finish_test