Fix a problem with "EXPLAIN QUERY PLAN SELECT count(*) FROM tbl".

FossilOrigin-Name: 9f9f32882501ac9b6e60f81195a64bdbf6e4497b

manifest

@@ -1,5 +1,5 @@
-C Have\sos_unix.c\scall\ssqlite3_log()\sfollowing\serrors\sin\scertain\ssystem\scalls.
-D 2011-02-21T11:46:24
+C Fix\sa\sproblem\swith\s"EXPLAIN\sQUERY\sPLAN\sSELECT\scount(*)\sFROM\stbl".
+D 2011-02-21T17:49:49
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 27701a1653595a1f2187dc61c8117e00a6c1d50f
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -98,7 +98,7 @@ F ext/rtree/rtree_util.tcl 06aab2ed5b826545bf215fff90ecb9255a8647ea
 F ext/rtree/sqlite3rtree.h 1af0899c63a688e272d69d8e746f24e76f10a3f0
 F ext/rtree/tkt3363.test 142ab96eded44a3615ec79fba98c7bde7d0f96de
 F ext/rtree/viewrtree.tcl eea6224b3553599ae665b239bd827e182b466024
-F install-sh 9d4de14ab9fb0facae2f48780b874848cbf2f895 x
+F install-sh 9d4de14ab9fb0facae2f48780b874848cbf2f895
 F ltmain.sh 3ff0879076df340d2e23ae905484d8c15d5fdea8
 F main.mk 54190fab7cdba523e311c274c95ea480f32abfb5
 F mkdll.sh 7d09b23c05d56532e9d44a50868eb4b12ff4f74a
@@ -175,7 +175,7 @@ F src/printf.c df2ff3bb5409e8958136933342c46464fbd017e7
 F src/random.c cd4a67b3953b88019f8cd4ccd81394a8ddfaba50
 F src/resolve.c 1c0f32b64f8e3f555fe1f732f9d6f501a7f05706
 F src/rowset.c 69afa95a97c524ba6faf3805e717b5b7ae85a697
-F src/select.c ae2f38effc99cfb9d8ebce36249d938487b3230d
+F src/select.c d24406c45dd2442eb2eeaac413439066b149c944
 F src/shell.c 649c51979812f77f97507024a4cea480c6862b8b
 F src/sqlite.h.in 388fca88d54577f671dc98bd805ff16085eabac1
 F src/sqlite3ext.h c90bd5507099f62043832d73f6425d8d5c5da754
@@ -373,7 +373,7 @@ F test/enc.test e54531cd6bf941ee6760be041dff19a104c7acea
 F test/enc2.test 6d91a5286f59add0cfcbb2d0da913b76f2242398
 F test/enc3.test 5c550d59ff31dccdba5d1a02ae11c7047d77c041
 F test/enc4.test 4b575ef09e0eff896e73bd24076f96c2aa6a42de
-F test/eqp.test 8f535d902b2df780d22edb95113880480664f976
+F test/eqp.test f14fadd76da53405e9885e2431cacf7191d83cdb
 F test/eval.test bc269c365ba877554948441e91ad5373f9f91be3
 F test/exclusive.test 53e1841b422e554cecf0160f937c473d6d0e3062
 F test/exclusive2.test 343d55130c12c67b8bf10407acec043a6c26c86b
@@ -597,7 +597,7 @@ F test/permutations.test 5b2a4cb756ffb2407cb4743163668d1d769febb6
 F test/pragma.test fdfc09067ea104a0c247a1a79d8093b56656f850
 F test/pragma2.test 5364893491b9231dd170e3459bfc2e2342658b47
 F test/printf.test 05970cde31b1a9f54bd75af60597be75a5c54fea
-F test/progress.test 5b075c3c790c7b2a61419bc199db87aaf48b8301
+F test/progress.test 5b075c3c790c7b2a61419bc199db87aaf48b8301 x
 F test/ptrchng.test ef1aa72d6cf35a2bbd0869a649b744e9d84977fc
 F test/quick.test 1681febc928d686362d50057c642f77a02c62e57
 F test/quota.test ddafe133653093eb9a99ccd6264884ae43f9c9b8
@@ -883,7 +883,7 @@ F tool/genfkey.test 4196a8928b78f51d54ef58e99e99401ab2f0a7e5
 F tool/lemon.c dfd81a51b6e27e469ba21d01a75ddf092d429027
 F tool/lempar.c 01ca97f87610d1dac6d8cd96ab109ab1130e76dc
 F tool/mkkeywordhash.c d2e6b4a5965e23afb80fbe74bb54648cd371f309
-F tool/mkopts.tcl 66ac10d240cc6e86abd37dc908d50382f84ff46e
+F tool/mkopts.tcl 66ac10d240cc6e86abd37dc908d50382f84ff46e x
 F tool/mkspeedsql.tcl a1a334d288f7adfe6e996f2e712becf076745c97
 F tool/mksqlite3c.tcl cf44512a48112b1ba09590548660a5a6877afdb3
 F tool/mksqlite3h.tcl d76c226a5e8e1f3b5f6593bcabe5e98b3b1ec9ff
@@ -908,7 +908,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P e87d499a4f8a456111c1f96ca6da31d0810fb7c8
-R fd86ed6c132ac26057f4026c493ad018
+P 01076528a43b61ae20ef6969b7d326de9b5313e4
+R ea0b61d4a154cb9b4ce10e2d0f175950
 U dan
-Z 2bb27580b8cb6c1cd91c27a584f12f47
+Z bee26eb130eb27a9686da9ca1f7baaf2

manifest.uuid

@@ -1 +1 @@
-01076528a43b61ae20ef6969b7d326de9b5313e4
+9f9f32882501ac9b6e60f81195a64bdbf6e4497b

src/select.c

@@ -3618,6 +3618,32 @@ static void updateAccumulator(Parse *pParse, AggInfo *pAggInfo){
   sqlite3ExprCacheClear(pParse);
 }
 
+/*
+** Add a single OP_Explain instruction to the VDBE to explain a simple
+** count(*) query ("SELECT count(*) FROM pTab").
+*/
+#ifndef SQLITE_OMIT_EXPLAIN
+static void explainSimpleCount(
+  Parse *pParse,                  /* Parse context */
+  Table *pTab,                    /* Table being queried */
+  Index *pIdx                     /* Index used to optimize scan, or NULL */
+){
+  if( pParse->explain==2 ){
+    char *zEqp = sqlite3MPrintf(pParse->db, "SCAN TABLE %s %s%s(~%d rows)",
+        pTab->zName, 
+        pIdx ? "USING COVERING INDEX " : "",
+        pIdx ? pIdx->zName : "",
+        pTab->nRowEst
+    );
+    sqlite3VdbeAddOp4(
+        pParse->pVdbe, OP_Explain, pParse->iSelectId, 0, 0, zEqp, P4_DYNAMIC
+    );
+  }
+}
+#else
+# define explainSimpleCount(a,b,c)
+#endif
+
 /*
 ** Generate code for the SELECT statement given in the p argument.  
 **
@@ -4229,6 +4255,7 @@ int sqlite3Select(
         }
         sqlite3VdbeAddOp2(v, OP_Count, iCsr, sAggInfo.aFunc[0].iMem);
         sqlite3VdbeAddOp1(v, OP_Close, iCsr);
+        explainSimpleCount(pParse, pTab, pBest);
       }else
 #endif /* SQLITE_OMIT_BTREECOUNT */
       {

test/eqp.test

@@ -21,6 +21,8 @@ set testprefix eqp
 # eqp-2.*:        Tests for single select statements.
 # eqp-3.*:        Select statements that execute sub-selects.
 # eqp-4.*:        Compound select statements.
+# ...
+# eqp-7.*:        "SELECT count(*) FROM tbl" statements (VDBE code OP_Count).
 #
 
 proc det {args} { uplevel do_eqp_test $args }
@@ -507,6 +509,7 @@ set boilerplate {
   exit
 }
 
+# Do a "Print Explain Query Plan" test.
 proc do_peqp_test {tn sql res} {
   set fd [open script.tcl w]
   puts $fd [string map [list %SQL% $sql] $::boilerplate]
@@ -529,7 +532,47 @@ do_peqp_test 6.1 {
 0 0 0 COMPOUND SUBQUERIES 1 AND 2 (EXCEPT)
 }]
 
+#-------------------------------------------------------------------------
+# The following tests - eqp-7.* - test that queries that use the OP_Count
+# optimization return something sensible with EQP.
+#
+drop_all_tables
 
+do_execsql_test 7.0 {
+  CREATE TABLE t1(a, b);
+  CREATE TABLE t2(a, b);
+  CREATE INDEX i1 ON t2(a);
+}
+
+det 7.1 "SELECT count(*) FROM t1" {
+  0 0 0 {SCAN TABLE t1 (~1000000 rows)}
+}
+
+det 7.2 "SELECT count(*) FROM t2" {
+  0 0 0 {SCAN TABLE t2 USING COVERING INDEX i1(~1000000 rows)}
+}
+
+do_execsql_test 7.3 {
+  INSERT INTO t1 VALUES(1, 2);
+  INSERT INTO t1 VALUES(3, 4);
+
+  INSERT INTO t2 VALUES(1, 2);
+  INSERT INTO t2 VALUES(3, 4);
+  INSERT INTO t2 VALUES(5, 6);
+ 
+  ANALYZE;
+}
+
+db close
+sqlite3 db test.db
+
+det 7.4 "SELECT count(*) FROM t1" {
+  0 0 0 {SCAN TABLE t1 (~2 rows)}
+}
+
+det 7.5 "SELECT count(*) FROM t2" {
+  0 0 0 {SCAN TABLE t2 USING COVERING INDEX i1(~3 rows)}
+}
 
 
 finish_test