Enhance the EXPLAIN QUERY PLAN output to use symbolic names to describe

subqueries, where possible, instead of cryptic subquery index numbers.
And in other ways, make the EQP output cleaner and easier to read.  Little
code is changed, but many of the test results had to be tweaked to align
with the new output format.

FossilOrigin-Name: f8e28308fdb45fbdef30003320d653410d69bb8ec92eef35c4245a99e2d0603b

8 files changed, 40 insertions, 47 deletions

diff --git a/src/build.c b/src/build.c
index b6faf080d..b5ec40909 100644
--- a/src/build.c
+++ b/src/build.c
@@ -4263,7 +4263,7 @@ void sqlite3DropIndex(Parse *pParse, SrcList *pName, int ifExists){
   pIndex = sqlite3FindIndex(db, pName->a[0].zName, pName->a[0].zDatabase);
   if( pIndex==0 ){
     if( !ifExists ){
-      sqlite3ErrorMsg(pParse, "no such index: %S", pName, 0);
+      sqlite3ErrorMsg(pParse, "no such index: %S", pName->a);
     }else{
       sqlite3CodeVerifyNamedSchema(pParse, pName->a[0].zDatabase);
     }
diff --git a/src/insert.c b/src/insert.c
index 89b66baf0..2fbfcce4a 100644
--- a/src/insert.c
+++ b/src/insert.c
@@ -817,7 +817,7 @@ void sqlite3Insert(
           bIdListInOrder = 0;
         }else{
           sqlite3ErrorMsg(pParse, "table %S has no column named %s",
-              pTabList, 0, pColumn->a[i].zName);
+              pTabList->a, pColumn->a[i].zName);
           pParse->checkSchema = 1;
           goto insert_cleanup;
         }
@@ -945,7 +945,7 @@ void sqlite3Insert(
     if( nColumn!=(pTab->nCol-nHidden) ){
       sqlite3ErrorMsg(pParse, 
          "table %S has %d columns but %d values were supplied",
-         pTabList, 0, pTab->nCol-nHidden, nColumn);
+         pTabList->a, pTab->nCol-nHidden, nColumn);
      goto insert_cleanup;
     }
   }
diff --git a/src/printf.c b/src/printf.c
index 9aab863ed..6f3b5681a 100644
--- a/src/printf.c
+++ b/src/printf.c
@@ -29,7 +29,7 @@
 #define etSQLESCAPE2 10 /* Strings with '\'' doubled and enclosed in '',
                           NULL pointers replaced by SQL NULL.  %Q */
 #define etTOKEN      11 /* a pointer to a Token structure */
-#define etSRCLIST    12 /* a pointer to a SrcList */
+#define etSRCITEM    12 /* a pointer to a SrcItem */
 #define etPOINTER    13 /* The %p conversion */
 #define etSQLESCAPE3 14 /* %w -> Strings with '\"' doubled */
 #define etORDINAL    15 /* %r -> 1st, 2nd, 3rd, 4th, etc.  English only */
@@ -95,10 +95,16 @@ static const et_info fmtinfo[] = {
 
   /* All the rest are undocumented and are for internal use only */
   {  'T',  0, 0, etTOKEN,      0,  0 },
-  {  'S',  0, 0, etSRCLIST,    0,  0 },
+  {  'S',  0, 0, etSRCITEM,    0,  0 },
   {  'r', 10, 1, etORDINAL,    0,  0 },
 };
 
+/* Notes:
+**
+**    %S    Takes a pointer to SrcItem.  Shows name or database.name
+**    %!S   Like %S but prefer the zName over the zAlias
+*/
+
 /* Floating point constants used for rounding */
 static const double arRound[] = {
   5.0e-01, 5.0e-02, 5.0e-03, 5.0e-04, 5.0e-05,
@@ -853,21 +859,24 @@ void sqlite3_str_vappendf(
         length = width = 0;
         break;
       }
-      case etSRCLIST: {
-        SrcList *pSrc;
-        int k;
+      case etSRCITEM: {
         SrcItem *pItem;
         if( (pAccum->printfFlags & SQLITE_PRINTF_INTERNAL)==0 ) return;
-        pSrc = va_arg(ap, SrcList*);
-        k = va_arg(ap, int);
-        pItem = &pSrc->a[k];
+        pItem = va_arg(ap, SrcItem*);
         assert( bArgList==0 );
-        assert( k>=0 && k<pSrc->nSrc );
-        if( pItem->zDatabase ){
-          sqlite3_str_appendall(pAccum, pItem->zDatabase);
-          sqlite3_str_append(pAccum, ".", 1);
+        if( pItem->zAlias && !flag_altform2 ){
+          sqlite3_str_appendall(pAccum, pItem->zAlias);
+        }else if( pItem->zName ){
+          if( pItem->zDatabase ){
+            sqlite3_str_appendall(pAccum, pItem->zDatabase);
+            sqlite3_str_append(pAccum, ".", 1);
+          }
+          sqlite3_str_appendall(pAccum, pItem->zName);
+        }else if( pItem->zAlias ){
+          sqlite3_str_appendall(pAccum, pItem->zAlias);
+        }else if( pItem->pSelect ){
+          sqlite3_str_appendf(pAccum, "SUBQUERY %u", pItem->pSelect->selId);
         }
-        sqlite3_str_appendall(pAccum, pItem->zName);
         length = width = 0;
         break;
       }
diff --git a/src/select.c b/src/select.c
index e2fa051e5..cab90eb01 100644
--- a/src/select.c
+++ b/src/select.c
@@ -5782,7 +5782,7 @@ static void explainSimpleCount(
 ){
   if( pParse->explain==2 ){
     int bCover = (pIdx!=0 && (HasRowid(pTab) || !IsPrimaryKeyIndex(pIdx)));
-    sqlite3VdbeExplain(pParse, 0, "SCAN TABLE %s%s%s",
+    sqlite3VdbeExplain(pParse, 0, "SCAN %s%s%s",
         pTab->zName,
         bCover ? " USING COVERING INDEX " : "",
         bCover ? pIdx->zName : ""
@@ -6355,10 +6355,10 @@ int sqlite3Select(
      
       pItem->regReturn = ++pParse->nMem;
       sqlite3VdbeAddOp3(v, OP_InitCoroutine, pItem->regReturn, 0, addrTop);
-      VdbeComment((v, "%s", pItem->pTab->zName));
+      VdbeComment((v, "%!S", pItem));
       pItem->addrFillSub = addrTop;
       sqlite3SelectDestInit(&dest, SRT_Coroutine, pItem->regReturn);
-      ExplainQueryPlan((pParse, 1, "CO-ROUTINE %u", pSub->selId));
+      ExplainQueryPlan((pParse, 1, "CO-ROUTINE %!S", pItem));
       sqlite3Select(pParse, pSub, &dest);
       pItem->pTab->nRowLogEst = pSub->nSelectRow;
       pItem->fg.viaCoroutine = 1;
@@ -6402,17 +6402,17 @@ int sqlite3Select(
         ** a trigger, then we only need to compute the value of the subquery
         ** once. */
         onceAddr = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
-        VdbeComment((v, "materialize \"%s\"", pItem->pTab->zName));
+        VdbeComment((v, "materialize %!S", pItem));
       }else{
-        VdbeNoopComment((v, "materialize \"%s\"", pItem->pTab->zName));
+        VdbeNoopComment((v, "materialize %!S", pItem));
       }
       sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);
-      ExplainQueryPlan((pParse, 1, "MATERIALIZE %u", pSub->selId));
+      ExplainQueryPlan((pParse, 1, "MATERIALIZE %!S", pItem));
       sqlite3Select(pParse, pSub, &dest);
       pItem->pTab->nRowLogEst = pSub->nSelectRow;
       if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr);
       retAddr = sqlite3VdbeAddOp1(v, OP_Return, pItem->regReturn);
-      VdbeComment((v, "end %s", pItem->pTab->zName));
+      VdbeComment((v, "end %!S", pItem));
       sqlite3VdbeChangeP1(v, topAddr, retAddr);
       sqlite3ClearTempRegCache(pParse);
       if( pItem->fg.isCte && pItem->fg.isCorrelated==0 ){
diff --git a/src/shell.c.in b/src/shell.c.in
index 2ec454ffb..3e52e256f 100644
--- a/src/shell.c.in
+++ b/src/shell.c.in
@@ -5779,7 +5779,7 @@ static int lintFkeyIndexes(
     "  || fkey_collate_clause("
     "       f.[table], COALESCE(f.[to], p.[name]), s.name, f.[from]),' AND ')"
     ", "
-    "     'SEARCH TABLE ' || s.name || ' USING COVERING INDEX*('"
+    "     'SEARCH ' || s.name || ' USING COVERING INDEX*('"
     "  || group_concat('*=?', ' AND ') || ')'"
     ", "
     "     s.name  || '(' || group_concat(f.[from],  ', ') || ')'"
@@ -5799,7 +5799,7 @@ static int lintFkeyIndexes(
     "GROUP BY s.name, f.id "
     "ORDER BY (CASE WHEN ? THEN f.[table] ELSE s.name END)"
   ;
-  const char *zGlobIPK = "SEARCH TABLE * USING INTEGER PRIMARY KEY (rowid=?)";
+  const char *zGlobIPK = "SEARCH * USING INTEGER PRIMARY KEY (rowid=?)";
 
   for(i=2; i<nArg; i++){
     int n = strlen30(azArg[i]);
diff --git a/src/treeview.c b/src/treeview.c
index b696d764e..976558698 100644
--- a/src/treeview.c
+++ b/src/treeview.c
@@ -134,19 +134,11 @@ void sqlite3TreeViewSrcList(TreeView *pView, const SrcList *pSrc){
     StrAccum x;
     char zLine[100];
     sqlite3StrAccumInit(&x, 0, zLine, sizeof(zLine), 0);
-    sqlite3_str_appendf(&x, "{%d:*}", pItem->iCursor);
-    if( pItem->zDatabase ){
-      sqlite3_str_appendf(&x, " %s.%s", pItem->zDatabase, pItem->zName);
-    }else if( pItem->zName ){
-      sqlite3_str_appendf(&x, " %s", pItem->zName);
-    }
+    sqlite3_str_appendf(&x, "{%d:*} %!S", pItem->iCursor, pItem);
     if( pItem->pTab ){
       sqlite3_str_appendf(&x, " tab=%Q nCol=%d ptr=%p used=%llx",
            pItem->pTab->zName, pItem->pTab->nCol, pItem->pTab, pItem->colUsed);
     }
-    if( pItem->zAlias ){
-      sqlite3_str_appendf(&x, " (AS %s)", pItem->zAlias);
-    }
     if( pItem->fg.jointype & JT_LEFT ){
       sqlite3_str_appendf(&x, " LEFT-JOIN");
     }
diff --git a/src/trigger.c b/src/trigger.c
index 689c7c741..562084561 100644
--- a/src/trigger.c
+++ b/src/trigger.c
@@ -209,12 +209,12 @@ void sqlite3BeginTrigger(
   */
   if( pTab->pSelect && tr_tm!=TK_INSTEAD ){
     sqlite3ErrorMsg(pParse, "cannot create %s trigger on view: %S", 
-        (tr_tm == TK_BEFORE)?"BEFORE":"AFTER", pTableName, 0);
+        (tr_tm == TK_BEFORE)?"BEFORE":"AFTER", pTableName->a);
     goto trigger_orphan_error;
   }
   if( !pTab->pSelect && tr_tm==TK_INSTEAD ){
     sqlite3ErrorMsg(pParse, "cannot create INSTEAD OF"
-        " trigger on table: %S", pTableName, 0);
+        " trigger on table: %S", pTableName->a);
     goto trigger_orphan_error;
   }
 
@@ -611,7 +611,7 @@ void sqlite3DropTrigger(Parse *pParse, SrcList *pName, int noErr){
   }
   if( !pTrigger ){
     if( !noErr ){
-      sqlite3ErrorMsg(pParse, "no such trigger: %S", pName, 0);
+      sqlite3ErrorMsg(pParse, "no such trigger: %S", pName->a);
     }else{
       sqlite3CodeVerifyNamedSchema(pParse, zDb);
     }
diff --git a/src/wherecode.c b/src/wherecode.c
index a7a76fb70..771a50fc7 100644
--- a/src/wherecode.c
+++ b/src/wherecode.c
@@ -148,16 +148,8 @@ int sqlite3WhereExplainOneScan(
             || (wctrlFlags&(WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX));
 
     sqlite3StrAccumInit(&str, db, zBuf, sizeof(zBuf), SQLITE_MAX_LENGTH);
-    sqlite3_str_appendall(&str, isSearch ? "SEARCH" : "SCAN");
-    if( pItem->pSelect ){
-      sqlite3_str_appendf(&str, " SUBQUERY %u", pItem->pSelect->selId);
-    }else{
-      sqlite3_str_appendf(&str, " TABLE %s", pItem->zName);
-    }
-
-    if( pItem->zAlias ){
-      sqlite3_str_appendf(&str, " AS %s", pItem->zAlias);
-    }
+    str.printfFlags = SQLITE_PRINTF_INTERNAL;
+    sqlite3_str_appendf(&str, "%s %S", isSearch ? "SEARCH" : "SCAN", pItem);
     if( (flags & (WHERE_IPK|WHERE_VIRTUALTABLE))==0 ){
       const char *zFmt = 0;
       Index *pIdx;