Enhance the sqlite3_stmt_scanstatus() API and add sqlite3_stmt_scanstatus_v2(). For creation of easier to read query performance reports.

FossilOrigin-Name: 55800833645739efeddcacef464c623931cb6aeb43f4219b4e4faf473c25c8bb

test/scanstatus.test

@@ -36,7 +36,9 @@ proc do_scanstatus_test {tn res} {
   while {1} {
     set r [sqlite3_stmt_scanstatus $stmt $idx]
     if {[llength $r]==0} break
-    lappend ret {*}$r
+    foreach v {nLoop nVisit nEst zName zExplain} {
+      lappend ret $v [dict get $r $v]
+    }
     incr idx
   }
 
@@ -312,8 +314,8 @@ do_execsql_test 5.1.1 {
   SELECT count(*) FROM t1 WHERE a IN (SELECT b FROM t1 AS ii)
 } {2}
 do_scanstatus_test 5.1.2 { 
-  nLoop 1 nVisit 10 nEst 10.0 zName t1bc 
-  zExplain {SCAN ii USING COVERING INDEX t1bc}
+  nLoop 1 nVisit 10 nEst 10.0 zName t1
+  zExplain {SCAN ii}
   nLoop 1 nVisit 2 nEst 8.0 zName sqlite_autoindex_t1_1
   zExplain {SEARCH t1 USING COVERING INDEX sqlite_autoindex_t1_1 (a=?)}
 }
@@ -341,15 +343,15 @@ do_eqp_test 5.4.1 {
   SELECT count(*) FROM t1, t2 WHERE y = c;
 } {
   QUERY PLAN
-  |--SCAN t1 USING COVERING INDEX t1bc
+  |--SCAN t1
   `--SEARCH t2 USING COVERING INDEX t2xy (ANY(x) AND y=?)
 }
 do_execsql_test 5.4.2 {
   SELECT count(*) FROM t1, t2 WHERE y = c;
 } {200}
 do_scanstatus_test 5.4.3 { 
-  nLoop 1 nVisit 10 nEst 10.0 zName t1bc 
-  zExplain {SCAN t1 USING COVERING INDEX t1bc}
+  nLoop 1 nVisit 10 nEst 10.0 zName t1
+  zExplain {SCAN t1}
   nLoop 10 nVisit 200 nEst 56.0 zName t2xy 
   zExplain {SEARCH t2 USING COVERING INDEX t2xy (ANY(x) AND y=?)}
 }

test/scanstatus2.test

@@ -0,0 +1,137 @@
+# 2014 November 1
+#
+# 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 scanstatus2
+
+ifcapable !scanstatus {
+  finish_test
+  return
+}
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(a, b);
+  CREATE TABLE t2(x, y);
+  INSERT INTO t1 VALUES(1, 2);
+  INSERT INTO t1 VALUES(3, 4);
+  INSERT INTO t2 VALUES('a', 'b');
+  INSERT INTO t2 VALUES('c', 'd');
+  INSERT INTO t2 VALUES('e', 'f');
+}
+
+proc do_zexplain_test {v2 tn sql res} {
+  db eval $sql
+  set stmt [db version -last-stmt-ptr]
+  set idx 0
+  set ret [list]
+
+  set cmd sqlite3_stmt_scanstatus
+  set f [list]
+  if {$v2} { lappend f complex }
+
+  while {1} {
+    set r [sqlite3_stmt_scanstatus -flags $f $stmt $idx]
+    if {[llength $r]==0} break
+    lappend ret [dict get $r zExplain]
+    incr idx
+  }
+  uplevel [list do_test $tn [list set {} $ret] [list {*}$res]]
+}
+
+proc get_cycles {stmt} {
+  set r [sqlite3_stmt_scanstatus $stmt -1]
+  dict get $r nCycle
+}
+
+proc foreach_scan {varname stmt body} {
+  upvar $varname var
+
+  for {set ii 0} {1} {incr ii} {
+    set r [sqlite3_stmt_scanstatus -flags complex $stmt $ii]
+    if {[llength $r]==0} break
+    array set var $r
+    uplevel $body
+  }
+}
+
+proc get_eqp_graph {stmt iPar nIndent} {
+  set res ""
+  foreach_scan A $stmt {
+    if {$A(iParentId)==$iPar} {
+      set txt $A(zExplain)
+      if {$A(nCycle)>=0} {
+        append txt " (nCycle=$A(nCycle))"
+      }
+      append res "[string repeat - $nIndent]$txt\n"
+      append res [get_eqp_graph $stmt $A(iSelectId) [expr $nIndent+2]]
+    }
+  }
+  set res
+}
+
+proc get_graph {stmt} {
+  set nCycle [get_cycles $stmt]
+  set res "QUERY (nCycle=$nCycle)\n"
+  append res [get_eqp_graph $stmt 0 2]
+}
+
+proc do_graph_test {tn sql res} {
+  db eval $sql
+  set stmt [db version -last-stmt-ptr]
+
+  set graph [string trim [get_graph $stmt]]
+  set graph [regsub -all {nCycle=[0-9]+} $graph nCycle=nnn]
+  uplevel [list do_test $tn [list set {} $graph] [string trim $res]]
+}
+
+
+do_zexplain_test 0 1.1 {
+  SELECT (SELECT a FROM t1 WHERE b=x) FROM t2 WHERE y=2
+} {
+  {SCAN t2}
+  {SCAN t1}
+}
+do_zexplain_test 1 1.2 {
+  SELECT (SELECT a FROM t1 WHERE b=x) FROM t2 WHERE y=2
+} {
+  {SCAN t2}
+  {CORRELATED SCALAR SUBQUERY 1}
+  {SCAN t1}
+}
+
+do_graph_test 1.3 {
+  SELECT (SELECT a FROM t1 WHERE b=x) FROM t2 WHERE y=2
+} {
+QUERY (nCycle=nnn)
+--SCAN t2
+--CORRELATED SCALAR SUBQUERY 1 (nCycle=nnn)
+----SCAN t1
+}
+
+do_graph_test 1.4 {
+  WITH v2(x,y) AS MATERIALIZED (
+    SELECT x,y FROM t2
+  )
+  SELECT * FROM t1, v2 ORDER BY y;
+} {
+QUERY (nCycle=nnn)
+--MATERIALIZE v2 (nCycle=nnn)
+----SCAN t2
+--SCAN v2
+--SCAN t1
+--USE TEMP B-TREE FOR ORDER BY
+}
+
+finish_test
+
+