From 97601244e2760e942b55a573414221a97022ee4b Mon Sep 17 00:00:00 2001
From: drh <>
Date: Mon, 15 Dec 2025 17:32:56 +0000
Subject: [PATCH] Enhance the vtablog extension so that it shows the value of
 sqlite3_vtab_distinct() in xBestIndex, and so that provides the new
 consume_order_by option that can cause xBestIndex to set the orderByConsumed
 flag.

FossilOrigin-Name: b158fe929929ae209f2603b11a2c4f44ad9147f6b2ce09a10ec1f92429402631
---
 ext/misc/vtablog.c | 54 ++++++++++++++++++++++++++++++++++++++++------
 manifest           | 12 +++++------
 manifest.uuid      |  2 +-
 3 files changed, 55 insertions(+), 13 deletions(-)

diff --git a/ext/misc/vtablog.c b/ext/misc/vtablog.c
index 2b3e303559..1e28495dea 100644
--- a/ext/misc/vtablog.c
+++ b/ext/misc/vtablog.c
@@ -14,6 +14,8 @@
 ** on stdout when its key interfaces are called.  This is intended for
 ** interactive analysis and debugging of virtual table interfaces.
 **
+** HOW TO COMPILE:
+**
 ** To build this extension as a separately loaded shared library or
 ** DLL, use compiler command-lines similar to the following:
 **
@@ -21,7 +23,7 @@
 **   (mac)      clang -fPIC -dynamiclib vtablog.c -o vtablog.dylib
 **   (windows)  cl vtablog.c -link -dll -out:vtablog.dll
 **
-** Usage example:
+** USAGE EXAMPLE:
 **
 **     .load ./vtablog
 **     CREATE VIRTUAL TABLE temp.log USING vtablog(
@@ -29,6 +31,23 @@
 **        rows=25
 **     );
 **     SELECT * FROM log;
+**
+** ARGUMENTS TO CREATE VIRTUAL TABLE:
+**
+** In "CREATE VIRTUAL TABLE temp.log AS vtablog(ARGS....)" statement, the
+** ARGS argument is a list of key-value pairs that can be any of the
+** following.
+**
+**     schema=TEXT            Text is a CREATE TABLE statement that defines
+**                            the schema of the new virtual table.
+**
+**     rows=N                 The table as N rows.
+**
+**     consume_order_by=N     If the left-most ORDER BY terms is ASC and
+**                            against column N (where the leftmost column
+**                            is #1) then set the orderByConsumed=1 flag in
+**                            xBestIndex.  Or if the left-most ORDER BY is
+**                            DESC and against column -N, do likewise.
 */
 #include "sqlite3ext.h"
 SQLITE_EXTENSION_INIT1
@@ -49,6 +68,8 @@ struct vtablog_vtab {
   char *zName;        /* Table name.  argv[2] of xConnect/xCreate */
   int nRow;           /* Number of rows in the table */
   int nCursor;        /* Number of cursors created */
+  int iConsumeOB;     /* Consume the ORDER BY clause if on column N-th
+                      ** and consumeOB=N or consumeOB=(-N) and DESC */
 };
 
 /* vtablog_cursor is a subclass of sqlite3_vtab_cursor which will
@@ -180,6 +201,7 @@ static int vtablogConnectCreate(
   int rc;
   char *zSchema = 0;
   char *zNRow = 0;
+  char *zConsumeOB = 0;
 
   printf("%s.%s.%s():\n", argv[1], argv[2], 
          isCreate ? "xCreate" : "xConnect");
@@ -203,6 +225,10 @@ static int vtablogConnectCreate(
       rc = SQLITE_ERROR;
       goto vtablog_end_connect;
     }
+    if( vtablog_string_parameter(pzErr, "consume_order_by", z, &zConsumeOB) ){
+      rc = SQLITE_ERROR;
+      goto vtablog_end_connect;
+    }
   }
   if( zSchema==0 ){
     zSchema = sqlite3_mprintf("%s","CREATE TABLE x(a,b);");
@@ -221,6 +247,10 @@ static int vtablogConnectCreate(
     pNew->nRow = 10;
     if( zNRow ) pNew->nRow = atoi(zNRow);
     printf("  nrow = %d\n", pNew->nRow);
+    if( zConsumeOB ) pNew->iConsumeOB = atoi(zConsumeOB);
+    if( pNew->iConsumeOB ){
+      printf("  consume_order_by = %d\n", pNew->iConsumeOB);
+    }
     pNew->zDb = sqlite3_mprintf("%s", argv[1]);
     pNew->zName = sqlite3_mprintf("%s", argv[2]);
   }
@@ -228,6 +258,7 @@ static int vtablogConnectCreate(
 vtablog_end_connect:
   sqlite3_free(zSchema);
   sqlite3_free(zNRow);
+  sqlite3_free(zConsumeOB);
   return rc;
 }
 static int vtablogCreate(
@@ -514,16 +545,27 @@ static int vtablogBestIndex(
     }
   }
   printf("  nOrderBy: %d\n", p->nOrderBy);
-  for(i=0; i<p->nOrderBy; i++){
-    printf("  orderby[%d]: col=%d desc=%d\n",
-       i,
-       p->aOrderBy[i].iColumn,
-       p->aOrderBy[i].desc);
+  if( p->nOrderBy ){
+    for(i=0; i<p->nOrderBy; i++){
+      printf("  orderby[%d]: col=%d desc=%d\n",
+         i,
+         p->aOrderBy[i].iColumn,
+         p->aOrderBy[i].desc);
+    }
+    if( pTab->iConsumeOB ){
+      int N = p->aOrderBy[0].iColumn+1;
+      if( (p->aOrderBy[0].desc && N==-pTab->iConsumeOB)
+       || (!p->aOrderBy[0].desc && N==pTab->iConsumeOB)
+      ){
+        p->orderByConsumed = 1;
+      }
+    }
   }
   p->estimatedCost = (double)500;
   p->estimatedRows = 500;
   printf("  idxNum=%d\n", p->idxNum);
   printf("  idxStr=NULL\n");
+  printf("  sqlite3_vtab_distinct()=%d\n", sqlite3_vtab_distinct(p));
   printf("  orderByConsumed=%d\n", p->orderByConsumed);
   printf("  estimatedCost=%g\n", p->estimatedCost);
   printf("  estimatedRows=%lld\n", p->estimatedRows);
diff --git a/manifest b/manifest
index 8ab80233db..d2c6733baf 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Clarify\sthe\saffect\sof\snCharLimit,\snLineLimit,\sand\snTitleLimit\son\sthe\nxRender\soutput\sfrom\sQRF.
-D 2025-12-15T13:58:41.145
+C Enhance\sthe\svtablog\sextension\sso\sthat\sit\sshows\sthe\svalue\sof\nsqlite3_vtab_distinct()\sin\sxBestIndex,\sand\sso\sthat\sprovides\sthe\snew\nconsume_order_by\soption\sthat\scan\scause\sxBestIndex\sto\sset\sthe\norderByConsumed\sflag.
+D 2025-12-15T17:32:56.417
 F .fossil-settings/binary-glob 61195414528fb3ea9693577e1980230d78a1f8b0a54c78cf1b9b24d0a409ed6a x
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
@@ -410,7 +410,7 @@ F ext/misc/uuid.c 5bb2264c1b64d163efa46509544fd7500cb8769cb7c16dd52052da8d961505
 F ext/misc/vfslog.c 3932ab932eeb2601dbc4447cb14d445aaa9fbe43b863ef5f014401c3420afd20
 F ext/misc/vfsstat.c 0b23c0a69a2b63dc0ef0af44f9c1fc977300c480a1f7a9814500369d8211f56e
 F ext/misc/vfstrace.c 0e4b8b17ac0675ea90f6d168d8214687e06ca3efbc0060aad4814994d82b41fb
-F ext/misc/vtablog.c 2d04386c2f5a3bb93bc9ae978f0b7dcd5a264e126abd640dd6d82aa9067cbd48
+F ext/misc/vtablog.c 402496fb38add7dd2c50f2a0ad20f83a9916ceab48dcd31e62ad621e663c83ac
 F ext/misc/vtshim.c e5bce24ab8c532f4fdc600148718fe1802cb6ed57417f1c1032d8961f72b0e8f
 F ext/misc/wholenumber.c 0fa0c082676b7868bf2fa918e911133f2b349bcdceabd1198bba5f65b4fc0668
 F ext/misc/windirent.h 02211ce51f3034c675f2dbf4d228194d51b3ee05734678bad5106fff6292e60c
@@ -2184,8 +2184,8 @@ F tool/version-info.c 33d0390ef484b3b1cb685d59362be891ea162123cea181cb8e6d2cf6dd
 F tool/warnings-clang.sh bbf6a1e685e534c92ec2bfba5b1745f34fb6f0bc2a362850723a9ee87c1b31a7
 F tool/warnings.sh d924598cf2f55a4ecbc2aeb055c10bd5f48114793e7ba25f9585435da29e7e98
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 5cf9e99ff8279530cb73a24794107591f8dab755fe78acd6c11429e532f3d1bf
-R 61f1b2124f9d7a4acd1b4a3d4268eab3
+P 881534858de8bccffca53e7256a725378a98a354e792374d972b120880c2ae78
+R 516b4041a52e0f6a1c6a30026e823eb8
 U drh
-Z d5b44ebdba76bbdfb15b0fa610193449
+Z 2dd134e29e053422231bfb06d9c85c41
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 67f294f401..b1dafb2f7a 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-881534858de8bccffca53e7256a725378a98a354e792374d972b120880c2ae78
+b158fe929929ae209f2603b11a2c4f44ad9147f6b2ce09a10ec1f92429402631
-- 
2.47.3