A few simple test cases for the omit-unused-subquery-column optimization.

FossilOrigin-Name: cf8f57c53425d89619ece10edc197d7d28946d3b23fcb4f526330196c76d9cc1

manifest

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-C Provide\san\soptimization-disable\smask\sfor\sthis\soptimization.\s\sDo\snot\sdo\sthe\noptimization\sif\sthe\ssubquery\sis\san\saggregate\sor\sis\sdistinct,\sbut\sallow\sit\sto\nbe\san\sephemeral\ssubquery.\s\sDo\snot\somit\scolumns\sthat\sare\sused\sin\sthe\sORDER\sBY\nof\sthe\ssubquery.
-D 2023-02-16T18:04:49.549
+C A\sfew\ssimple\stest\scases\sfor\sthe\somit-unused-subquery-column\soptimization.
+D 2023-02-16T19:41:39.707
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 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -1462,6 +1462,7 @@ F test/selectD.test 6d1909b49970bf92f45ce657505befcef5fc7cbc13544e18103a316d3218
 F test/selectE.test a8730ca330fcf40ace158f134f4fe0eb00c7edbf
 F test/selectF.test 21c94e6438f76537b72532fa9fd4710cdd455fc3
 F test/selectG.test 089f7d3d7e6db91566f00b036cb353107a2cca6220eb1cb264085a836dae8840
+F test/selectH.test a1fed72a83a68ed858db6fcf6d8ddccc4a368645c0ef48dc3ac331d41efe34de
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@@ -2045,8 +2046,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
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-Z aa83be3d588d7cfee260c5a1a1ab587b
+Z 7d95cef9a9f7a288c86a6fe2f6e032bb
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manifest.uuid

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+cf8f57c53425d89619ece10edc197d7d28946d3b23fcb4f526330196c76d9cc1

test/selectH.test

@@ -0,0 +1,110 @@
+# 2023-02-16
+#
+# 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 the omit-unused-subquery-column optimization.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+set testprefix selectH
+
+do_execsql_test 1.1 {
+  CREATE TABLE t1(
+     c0,  c1,  c2,  c3,  c4,  c5,  c6,  c7,  c8,  c9,
+     c10, c11, c12, c13, c14, c15, c16, c17, c18, c19,
+     c20, c21, c22, c23, c24, c25, c26, c27, c28, c29,
+     c30, c31, c32, c33, c34, c35, c36, c37, c38, c39,
+     c40, c41, c42, c43, c44, c45, c46, c47, c48, c49,
+     c50, c51, c52, c53, c54, c55, c56, c57, c58, c59,
+     c60, c61, c62, c63, c64, c65
+  );
+  INSERT INTO t1 VALUES(
+     0,  1,  2,  3,  4,  5,  6,  7,  8,  9,
+     10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
+     20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
+     30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
+     40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
+     50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
+     60, 61, 62, 63, 64, 65
+  );
+  CREATE INDEX t1c60 ON t1(c60);
+}
+
+# The SQL counter(N) function adjusts the value of the global
+# TCL variable ::selectH_cnt by the value N and returns the new
+# value.  By putting calls to counter(N) as unused columns in a
+# view or subquery, we can check to see if the counter gets incremented,
+# and if not that means that the unused column was omitted.
+#
+unset -nocomplain selectH_cnt
+set selectH_cnt 0
+proc selectH_counter {amt} {
+  global selectH_cnt
+  incr selectH_cnt $amt
+  return $selectH_cnt
+}
+db func counter selectH_counter
+
+do_execsql_test 1.2 {
+  SELECT DISTINCT c44 FROM (
+    SELECT c0 AS a, *, counter(1) FROM t1
+    UNION ALL
+    SELECT c1 AS a, *, counter(1) FROM t1
+  ) WHERE c60=60;
+} {44}
+do_test 1.3 {
+  set ::selectH_cnt
+} {0}
+
+do_execsql_test 2.1 {
+  SELECT a FROM (
+    SELECT counter(1) AS cnt, c15 AS a, *, c62 AS b FROM t1
+    UNION ALL
+    SELECT counter(1) AS cnt, c16 AS a, *, c61 AS b FROM t1
+    ORDER BY b
+  );
+} {16 15}
+do_test 2.2 {
+  set ::selectH_cnt
+} {0}
+
+do_execsql_test 3.1 {
+  CREATE VIEW v1 AS
+    SELECT c16 AS a, *, counter(1) AS x FROM t1
+    UNION ALL
+    SELECT c17 AS a, *, counter(1) AS x FROM t1
+    UNION ALL
+    SELECT c18 AS a, *, counter(1) AS x FROM t1
+    UNION ALL
+    SELECT c19 AS a, *, counter(1) AS x FROM t1;
+  SELECT count(*) FROM v1 WHERE c60=60;
+} {4}
+do_test 3.2 {
+  set ::selectH_cnt
+} {0}
+do_execsql_test 3.3 {
+  SELECT count(a) FROM v1 WHERE c60=60;
+} {4}
+do_execsql_test 3.4 {
+  SELECT a FROM v1 WHERE c60=60;
+} {16 17 18 19}
+do_test 3.5 {
+  set ::selectH_cnt
+} {0}
+do_execsql_test 3.6 {
+  SELECT x FROM v1 WHERE c60=60;
+} {1 2 3 4}
+do_test 3.7 {
+  set ::selectH_cnt
+} {4}
+
+
+finish_test