diff --git a/manifest b/manifest
index f320f73030..989f928c10 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\san\sincorrect\sassert()\sstatement\sin\ssqlite3GenerateConstraintChecks().\ndbsqlfuzz\s4190cff310aeab359a55f354e560db95d3a6f47d
-D 2021-10-30T18:17:59.636
+C Add\sthe\ssqlite3_autovacuum_pages()\sinterface.
+D 2021-10-30T20:22:32.855
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -490,7 +490,7 @@ F src/auth.c f4fa91b6a90bbc8e0d0f738aa284551739c9543a367071f55574681e0f24f8cf
 F src/backup.c 3014889fa06e20e6adfa0d07b60097eec1f6e5b06671625f476a714d2356513d
 F src/bitvec.c 7c849aac407230278445cb069bebc5f89bf2ddd87c5ed9459b070a9175707b3d
 F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
-F src/btree.c 004c647dfb5332ee4b56385f3ac264ebea781cb00f7a1561a48f4a45b78fed61
+F src/btree.c 2c8a52a7fd84b1aec4a79e7861b6368aecbf011a43247cc7d9a2946c7f0ae5ea
 F src/btree.h 74d64b8f28cfa4a894d14d4ed64fa432cd697b98b61708d4351482ae15913e22
 F src/btreeInt.h ee9348c4cb9077243b049edc93a82c1f32ca48baeabf2140d41362b9f9139ff7
 F src/build.c 8bdda90f9b1189c7b0813575171b3c6b2d74b3ade57c11cb4383776781ea9335
@@ -512,8 +512,8 @@ F src/hwtime.h cb1d7e3e1ed94b7aa6fde95ae2c2daccc3df826be26fc9ed7fd90d1750ae6144
 F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
 F src/insert.c 3f2892de7820d8e0b34a90bff8a3e2f879bc528683fa2ebb9e779ae56b64b741
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
-F src/loadext.c 0aa9e7f08e168e3874cb54984408e3976dafdf5616d511952c425b5ac088ea3e
-F src/main.c bfe067d61ebbd0e6eb023f1fb6b353021e621cf1657e061d629064a740bfbf6f
+F src/loadext.c e1dcff1c916bf6834e150b492eddda5d9792453182d2ad64294d2266b6e93c4c
+F src/main.c 546dd2418c4f5d59aced76c68e55290735feb420ee305051fbd55ab8fff0d255
 F src/malloc.c ef796bcc0e81d845d59a469f1cf235056caf9024172fd524e32136e65593647b
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c c12a42539b1ba105e3707d0e628ad70e611040d8f5e38cf942cee30c867083de
@@ -551,15 +551,15 @@ F src/resolve.c ae65c88f5d0d4bc0052b203773d407efa2387c2bd6b202f87178006c7bb8632c
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
 F src/select.c 32d25b5af6c708aa63373c78c2e59681910387a7a78c08ec3086cadc77d41627
 F src/shell.c.in 185e4b905c3a399e9376597a04cf668f6f992513290978ac978cf4991954d89f
-F src/sqlite.h.in f0c1ecb5af508aa8e970cd8bc0ec851e6c380b81825038d458846c2fcdfcef50
+F src/sqlite.h.in 99786216caf1c57aa3d70f95a7f84566dff6a9eeb50174799ea3b387eafd2a22
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
-F src/sqlite3ext.h e97f4e9b509408fea4c4e9bef5a41608dfac343b4d3c7a990dedde1e19af9510
-F src/sqliteInt.h 317bbdf926ec7c391fb00bcaa1f82799836a1151568bd9d343f43c2cdf1a48b9
+F src/sqlite3ext.h d8f6f67ae9ad990a70dd03c093bcdc8883e159ff4bfd16a496f8fb80c6840b5a
+F src/sqliteInt.h 02f7ccc971d67d8641707f219b9c304113d43a9a128b73a39d1fcaa036c885b7
 F src/sqliteLimit.h d7323ffea5208c6af2734574bae933ca8ed2ab728083caa117c9738581a31657
 F src/status.c 4b8bc2a6905163a38b739854a35b826c737333fab5b1f8e03fa7eb9a4799c4c1
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
 F src/tclsqlite.c 428e813dabf82804bc13196af35a0c3c6ef4347fe557fa6717c5c66bba6e8520
-F src/test1.c 63761c2be2607f1b425fde991beda48aed384f8d67f2b4ee549174c88b433009
+F src/test1.c bd1c3c2637db35c0a69513e008c0e6a177b360ccae7689e0bf69f15b55e24bae
 F src/test2.c 3efb99ab7f1fc8d154933e02ae1378bac9637da5
 F src/test3.c 61798bb0d38b915067a8c8e03f5a534b431181f802659a6616f9b4ff7d872644
 F src/test4.c 7c4420e01c577b5c4add2cb03119743b1a357543d347773b9e717195ea967159
@@ -705,7 +705,8 @@ F test/autoindex2.test 12ef578928102baaa0dc23ad397601a2f4ecb0df
 F test/autoindex3.test 2d13958a5617e987624a428d7aed91bf51f322b49b476e3573fadec697ce6da5
 F test/autoindex4.test 49d3cd791a9baa16fb461d7ea3de80d019a819cf
 F test/autoindex5.test 2ee94f033b87ca0160e08d81034c507aff8e230df2627f0304fa309b2fee19a3
-F test/autovacuum.test 0831cd34e14695d297187f7f6519265e3121c5b0a1720e548e86829e796129e9
+F test/autovacuum.test 00671369bbf96c6a49989a9425f5b78b94075d6a4b031e5e00000c2c32f365df
+F test/autovacuum2.test 76f7eb4fe6a6bf6d33a196a7141dba98886d2fb53a268d7feca285d5da4759d7
 F test/autovacuum_ioerr2.test 8a367b224183ad801e0e24dcb7d1501f45f244b4
 F test/avfs.test 0c3a38e03cccb0fc3127838462dc05dc3f4c1480d770c084b388304c25de3652
 F test/avtrans.test b7dc25459ecbd86c6fa9c606ee3068f59d81e225118617dcf2bbb6ded2ade89e
@@ -1929,7 +1930,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 8ba73b3cadb72ffcf176d19f9f946c1b90b224e5ab9a0e9eb9a83affa7476d23
-R b527768918a8e4077efc0dd96c45874f
+P 623c0d086bda135c49bfc238c31498facdcbe8ecc7659cc1af61594df0c6e899 60cd9da9258e0b701d4bb3f9c91c5d0a12e925b9b937df619b09f33a287b4a33
+R c2365c0f257a6e1be84889548b719edd
+T +closed 60cd9da9258e0b701d4bb3f9c91c5d0a12e925b9b937df619b09f33a287b4a33
 U drh
-Z ea8a849e6713aaef4d0e7842051d5f8f
+Z 46db034af6d2112bb92acfe1ff1351cf
diff --git a/manifest.uuid b/manifest.uuid
index e54f60e5fa..0e9b7b2571 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-623c0d086bda135c49bfc238c31498facdcbe8ecc7659cc1af61594df0c6e899
\ No newline at end of file
+ca2703c339f76101f25051a2ed380398b018782883bfee68b5f2d69a1de9091a
\ No newline at end of file
diff --git a/src/btree.c b/src/btree.c
index 0d220a3b93..67611c3bf5 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -3939,16 +3939,18 @@ int sqlite3BtreeIncrVacuum(Btree *p){
 /*
 ** This routine is called prior to sqlite3PagerCommit when a transaction
 ** is committed for an auto-vacuum database.
-**
-** If SQLITE_OK is returned, then *pnTrunc is set to the number of pages
-** the database file should be truncated to during the commit process. 
-** i.e. the database has been reorganized so that only the first *pnTrunc
-** pages are in use.
 */
-static int autoVacuumCommit(BtShared *pBt){
+static int autoVacuumCommit(Btree *p){
   int rc = SQLITE_OK;
-  Pager *pPager = pBt->pPager;
-  VVA_ONLY( int nRef = sqlite3PagerRefcount(pPager); )
+  Pager *pPager;
+  BtShared *pBt;
+  sqlite3 *db;
+  VVA_ONLY( int nRef );
+
+  assert( p!=0 );
+  pBt = p->pBt;  
+  pPager = pBt->pPager;
+  VVA_ONLY( nRef = sqlite3PagerRefcount(pPager); )
 
   assert( sqlite3_mutex_held(pBt->mutex) );
   invalidateAllOverflowCache(pBt);
@@ -3956,6 +3958,7 @@ static int autoVacuumCommit(BtShared *pBt){
   if( !pBt->incrVacuum ){
     Pgno nFin;         /* Number of pages in database after autovacuuming */
     Pgno nFree;        /* Number of pages on the freelist initially */
+    Pgno nVac;         /* Number of pages to vacuum */
     Pgno iFree;        /* The next page to be freed */
     Pgno nOrig;        /* Database size before freeing */
 
@@ -3969,18 +3972,42 @@ static int autoVacuumCommit(BtShared *pBt){
     }
 
     nFree = get4byte(&pBt->pPage1->aData[36]);
-    nFin = finalDbSize(pBt, nOrig, nFree);
+    db = p->db;
+    if( db->xAutovacPages ){
+      int iDb;
+      for(iDb=0; ALWAYS(iDb<db->nDb); iDb++){
+        if( db->aDb[iDb].pBt==p ) break;
+      }
+      nVac = db->xAutovacPages(
+        db->pAutovacPagesArg,
+        db->aDb[iDb].zDbSName,
+        nOrig,
+        nFree,
+        pBt->pageSize
+      );
+      if( nVac>nFree ){
+        nVac = nFree;
+      }
+      if( nVac==0 ){
+        return SQLITE_OK;
+      }
+    }else{
+      nVac = nFree;
+    }
+    nFin = finalDbSize(pBt, nOrig, nVac);
     if( nFin>nOrig ) return SQLITE_CORRUPT_BKPT;
     if( nFin<nOrig ){
       rc = saveAllCursors(pBt, 0, 0);
     }
     for(iFree=nOrig; iFree>nFin && rc==SQLITE_OK; iFree--){
-      rc = incrVacuumStep(pBt, nFin, iFree, 1);
+      rc = incrVacuumStep(pBt, nFin, iFree, nVac==nFree);
     }
     if( (rc==SQLITE_DONE || rc==SQLITE_OK) && nFree>0 ){
       rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
-      put4byte(&pBt->pPage1->aData[32], 0);
-      put4byte(&pBt->pPage1->aData[36], 0);
+      if( nVac==nFree ){
+        put4byte(&pBt->pPage1->aData[32], 0);
+        put4byte(&pBt->pPage1->aData[36], 0);
+      }
       put4byte(&pBt->pPage1->aData[28], nFin);
       pBt->bDoTruncate = 1;
       pBt->nPage = nFin;
@@ -4031,7 +4058,7 @@ int sqlite3BtreeCommitPhaseOne(Btree *p, const char *zSuperJrnl){
     sqlite3BtreeEnter(p);
 #ifndef SQLITE_OMIT_AUTOVACUUM
     if( pBt->autoVacuum ){
-      rc = autoVacuumCommit(pBt);
+      rc = autoVacuumCommit(p);
       if( rc!=SQLITE_OK ){
         sqlite3BtreeLeave(p);
         return rc;
diff --git a/src/loadext.c b/src/loadext.c
index 29371336c4..4edefec0c9 100644
--- a/src/loadext.c
+++ b/src/loadext.c
@@ -483,6 +483,8 @@ static const sqlite3_api_routines sqlite3Apis = {
   /* Version 3.36.1 and later */
   sqlite3_changes64,
   sqlite3_total_changes64,
+  /* Version 3.37.0 and later */
+  sqlite3_autovacuum_pages,
 };
 
 /* True if x is the directory separator character
diff --git a/src/main.c b/src/main.c
index bf33b640b8..aa34977bf9 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1403,6 +1403,9 @@ void sqlite3LeaveMutexAndCloseZombie(sqlite3 *db){
   ** structure?
   */
   sqlite3DbFree(db, db->aDb[1].pSchema);
+  if( db->xAutovacDestr ){
+    db->xAutovacDestr(db->pAutovacPagesArg);
+  }
   sqlite3_mutex_leave(db->mutex);
   db->eOpenState = SQLITE_STATE_CLOSED;
   sqlite3_mutex_free(db->mutex);
@@ -2304,6 +2307,34 @@ void *sqlite3_preupdate_hook(
 }
 #endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
 
+/*
+** Register a function to be invoked prior to each autovacuum that
+** determines the number of pages to vacuum.
+*/
+int sqlite3_autovacuum_pages(
+  sqlite3 *db,                 /* Attach the hook to this database */
+  unsigned int (*xCallback)(void*,const char*,u32,u32,u32), 
+  void *pArg,                  /* Argument to the function */
+  void (*xDestructor)(void*)   /* Destructor for pArg */
+){
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    if( xDestructor ) xDestructor(pArg);
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  if( db->xAutovacDestr ){
+    db->xAutovacDestr(db->pAutovacPagesArg);
+  }
+  db->xAutovacPages = xCallback;
+  db->pAutovacPagesArg = pArg;
+  db->xAutovacDestr = xDestructor;
+  sqlite3_mutex_leave(db->mutex);
+  return SQLITE_OK;
+}
+
+
 #ifndef SQLITE_OMIT_WAL
 /*
 ** The sqlite3_wal_hook() callback registered by sqlite3_wal_autocheckpoint().
diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index 4435925de4..f20d457e3a 100644
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -6406,6 +6406,72 @@ sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);
 void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
 void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
 
+/*
+** CAPI3REF: Autovacuum Compaction Amount Callback
+** METHOD: sqlite3
+**
+** ^The sqlite3_autovacuum_pages(D,C,P,X) interface registers a callback 
+** function C that is invoked prior to each autovacuum of the database
+** file.  ^The callback is passed a copy of the generic data pointer (P),
+** the schema-name of the attached database that is being autovacuumed,
+** the the size of the database file in pages, the number of free pages,
+** and the number of bytes per page, respectively.  The callback should
+** return the number of free pages that should be removed by the
+** autovacuum.  ^If the callback returns zero, then no autovacuum happens.
+** ^If the value returned is greater than or equal to the number of
+** free pages, then a complete autovacuum happens.
+**
+** <p>^If there are multiple ATTACH-ed database files that are being
+** modified as part of a transaction commit, then the autovacuum pages
+** callback is invoked separately for each file.
+**
+** <p><b>The callback is not reentrant.</b> The callback function should
+** not attempt to invoke any other SQLite interface.  If it does, bad
+** things may happen, including segmentation faults and corrupt database
+** files.  The callback function should be a simple function that
+** does some arithmetic on its input parameters and returns a result.
+**
+** ^The X parameter to sqlite3_autovacuum_pages(D,C,P,X) is an optional
+** destructor for the P parameter.  ^If X is not NULL, then X(P) is
+** invoked whenever the database connection closes or when the callback
+** is overwritten by another invocation of sqlite3_autovacuum_pages().
+**
+** <p>^There is only one autovacuum pages callback per database connection.
+** ^Each call to the sqlite3_autovacuum_pages() interface overrides all
+** previous invocations for that database connection.  ^If the callback
+** argument (C) to sqlite3_autovacuum_pages(D,C,P,X) is a NULL pointer,
+** then the autovacuum steps callback is cancelled.  The return value
+** from sqlite3_autovacuum_pages() is normally SQLITE_OK, but might
+** be some other error code if something goes wrong.  The current
+** implementation will only return SQLITE_OK or SQLITE_MISUSE, but other
+** return codes might be added in future releases.
+**
+** <p>If no autovacuum pages callback is specified (the usual case) or
+** a NULL pointer is provided for the callback,
+** then the default behavior is to vacuum all free pages.  So, in other
+** words, the default behavior is the same as if the callback function
+** were something like this:
+**
+** <blockquote><pre>
+** &nbsp;   unsigned int demonstration_autovac_pages_callback(
+** &nbsp;     void *pClientData,
+** &nbsp;     const char *zSchema,
+** &nbsp;     unsigned int nDbPage,
+** &nbsp;     unsigned int nFreePage,
+** &nbsp;     unsigned int nBytePerPage
+** &nbsp;   ){
+** &nbsp;     return nFreePage;
+** &nbsp;   }
+** </pre></blockquote>
+*/
+int sqlite3_autovacuum_pages(
+  sqlite3 *db,
+  unsigned int(*)(void*,const char*,unsigned int,unsigned int,unsigned int),
+  void*,
+  void(*)(void*)
+);
+
+
 /*
 ** CAPI3REF: Data Change Notification Callbacks
 ** METHOD: sqlite3
diff --git a/src/sqlite3ext.h b/src/sqlite3ext.h
index 98d9305240..4ec11324b2 100644
--- a/src/sqlite3ext.h
+++ b/src/sqlite3ext.h
@@ -340,6 +340,10 @@ struct sqlite3_api_routines {
   /* Version 3.36.1 and later */
   sqlite3_int64 (*changes64)(sqlite3*);
   sqlite3_int64 (*total_changes64)(sqlite3*);
+  /* Version 3.37.0 and later */
+  int (*autovacuum_pages)(sqlite3*,
+     unsigned int(*)(void*,const char*,unsigned int,unsigned int,unsigned int),
+     void*, void(*)(void*));
 };
 
 /*
@@ -646,6 +650,11 @@ typedef int (*sqlite3_loadext_entry)(
 #define sqlite3_database_file_object   sqlite3_api->database_file_object
 /* Version 3.34.0 and later */
 #define sqlite3_txn_state              sqlite3_api->txn_state
+/* Version 3.36.1 and later */
+#define sqlite3_changes64              sqlite3_api->changes64
+#define sqlite3_total_changes64        sqlite3_api->total_changes64
+* Version 3.37.0 and later */
+#define sqlite3_autovacuum_pages       sqlite3_api->autovacuum_pages
 #endif /* !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION) */
 
 #if !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION)
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index cb20a37f24..53e9033183 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -1566,6 +1566,9 @@ struct sqlite3 {
   void (*xRollbackCallback)(void*); /* Invoked at every commit. */
   void *pUpdateArg;
   void (*xUpdateCallback)(void*,int, const char*,const char*,sqlite_int64);
+  void *pAutovacPagesArg;           /* Client argument to autovac_pages */
+  void (*xAutovacDestr)(void*);     /* Destructor for pAutovacPAgesArg */
+  unsigned int (*xAutovacPages)(void*,const char*,u32,u32,u32);
   Parse *pParse;                /* Current parse */
 #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
   void *pPreUpdateArg;          /* First argument to xPreUpdateCallback */
diff --git a/src/test1.c b/src/test1.c
index ceafbe5038..db14a607da 100644
--- a/src/test1.c
+++ b/src/test1.c
@@ -8233,6 +8233,96 @@ static int SQLITE_TCLAPI test_decode_hexdb(
   return TCL_OK;
 }
 
+/*
+** Client data for the autovacuum_pages callback.
+*/
+struct AutovacPageData {
+  Tcl_Interp *interp;
+  char *zScript;
+};
+typedef struct AutovacPageData AutovacPageData;
+
+/*
+** Callback functions for sqlite3_autovacuum_pages
+*/
+static unsigned int test_autovacuum_pages_callback(
+  void *pClientData,
+  const char *zSchema,
+  unsigned int nFilePages,
+  unsigned int nFreePages,
+  unsigned int nBytePerPage
+){
+  AutovacPageData *pData = (AutovacPageData*)pClientData;
+  Tcl_DString str;
+  unsigned int x;
+  char zBuf[100];
+  Tcl_DStringInit(&str);
+  Tcl_DStringAppend(&str, pData->zScript, -1);
+  Tcl_DStringAppendElement(&str, zSchema);
+  sqlite3_snprintf(sizeof(zBuf), zBuf, "%u", nFilePages);
+  Tcl_DStringAppendElement(&str, zBuf);
+  sqlite3_snprintf(sizeof(zBuf), zBuf, "%u", nFreePages);
+  Tcl_DStringAppendElement(&str, zBuf);
+  sqlite3_snprintf(sizeof(zBuf), zBuf, "%u", nBytePerPage);
+  Tcl_DStringAppendElement(&str, zBuf);
+  Tcl_ResetResult(pData->interp);
+  Tcl_Eval(pData->interp, Tcl_DStringValue(&str));
+  Tcl_DStringFree(&str);
+  x = nFreePages;
+  (void)Tcl_GetIntFromObj(0, Tcl_GetObjResult(pData->interp), (int*)&x);
+  return x;
+}
+
+/*
+** Usage:  sqlite3_autovacuum_pages DB SCRIPT
+**
+** Add an autovacuum-pages callback to database connection DB.  The callback
+** will invoke SCRIPT, after appending parameters.
+**
+** If SCRIPT is an empty string or is omitted, then the callback is
+** cancelled.
+*/
+static int SQLITE_TCLAPI test_autovacuum_pages(
+  void * clientData,
+  Tcl_Interp *interp,
+  int objc,
+  Tcl_Obj *CONST objv[]
+){
+  AutovacPageData *pData;
+  sqlite3 *db;
+  int rc;
+  const char *zScript;
+  if( objc!=2 && objc!=3 ){
+    Tcl_WrongNumArgs(interp, 1, objv, "DB ?SCRIPT?");
+    return TCL_ERROR;
+  }
+  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
+  zScript = objc==3 ? Tcl_GetString(objv[2]) : 0;
+  if( zScript ){
+    size_t nScript = strlen(zScript);
+    pData = sqlite3_malloc64( sizeof(*pData) + nScript + 1 );
+    if( pData==0 ){
+      Tcl_AppendResult(interp, "out of memory", (void*)0);
+      return TCL_ERROR;
+    }
+    pData->interp = interp;
+    pData->zScript = (char*)&pData[1];
+    memcpy(pData->zScript, zScript, nScript+1);
+    rc = sqlite3_autovacuum_pages(db,test_autovacuum_pages_callback,
+                                  pData, sqlite3_free);
+  }else{
+    rc = sqlite3_autovacuum_pages(db, 0, 0, 0);
+  }
+  if( rc ){
+    char zBuf[1000];
+    sqlite3_snprintf(sizeof(zBuf), zBuf,
+       "sqlite3_autovacuum_pages() returns %d", rc);
+    Tcl_AppendResult(interp, zBuf, (void*)0);
+    return TCL_ERROR;
+  }
+  return TCL_OK;
+}
+
 
 /*
 ** Register commands with the TCL interpreter.
@@ -8524,6 +8614,7 @@ int Sqlitetest1_Init(Tcl_Interp *interp){
      { "atomic_batch_write",      test_atomic_batch_write, 0 },
      { "sqlite3_mmap_warm",       test_mmap_warm,          0 },
      { "sqlite3_config_sorterref", test_config_sorterref,   0 },
+     { "sqlite3_autovacuum_pages", test_autovacuum_pages,   0 },
      { "decode_hexdb",             test_decode_hexdb,       0 },
      { "test_write_db",            test_write_db,           0 },
      { "sqlite3_register_cksumvfs", test_register_cksumvfs,  0 },
diff --git a/test/autovacuum.test b/test/autovacuum.test
index 431c4b8a2a..245ea8b51d 100644
--- a/test/autovacuum.test
+++ b/test/autovacuum.test
@@ -9,9 +9,8 @@
 #
 #***********************************************************************
 # This file implements regression tests for SQLite library.  The
-# focus of this file is testing the SELECT statement.
+# focus of this file is testing the autovacuum feature.
 #
-# $Id: autovacuum.test,v 1.29 2009/04/06 17:50:03 danielk1977 Exp $
 
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
diff --git a/test/autovacuum2.test b/test/autovacuum2.test
new file mode 100644
index 0000000000..a3c409839e
--- /dev/null
+++ b/test/autovacuum2.test
@@ -0,0 +1,87 @@
+# 2021-10-15
+#
+# 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.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this file is testing the sqlite3_autovacuum_pages() interface
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+# If this build of the library does not support auto-vacuum, omit this
+# whole file.
+ifcapable {!autovacuum || !pragma} {
+  finish_test
+  return
+}
+
+# Demonstrate basic sqlite3_autovacuum_pages functionality
+#
+do_execsql_test autovacuum2-1.0 {
+  PRAGMA page_size=1024;
+  PRAGMA auto_vacuum=FULL;
+  CREATE TABLE t1(x);
+  VACUUM;
+  INSERT INTO t1(x) VALUES(zeroblob(10000));
+  PRAGMA page_count;
+} {12}
+proc autovac_page_callback {schema filesize freesize pagesize} {
+  global autovac_callback_data
+  lappend autovac_callback_data $schema $filesize $freesize $pagesize
+  return [expr {$freesize/2}]
+}
+sqlite3_autovacuum_pages db autovac_page_callback
+set autovac_callback_data {}
+do_execsql_test autovacuum2-1.1 {
+  BEGIN;
+  DELETE FROM t1;
+  PRAGMA freelist_count;
+  PRAGMA page_count;
+} {9 12}
+do_execsql_test autovacuum2-1.2 {
+  COMMIT;
+} {}
+do_test autovacuum2-1.3 {
+  set autovac_callback_data
+} {main 12 9 1024}
+do_execsql_test autovacuum2-1.4 {
+  PRAGMA freelist_count;
+  PRAGMA page_count;
+} {5 8}
+do_execsql_test autovacuum2-1.5 {
+  PRAGMA integrity_check;
+} {ok}
+
+# Disable the autovacuum-pages callback.  Then do any transaction.
+# The database should shrink to minimal size
+#
+sqlite3_autovacuum_pages db
+do_execsql_test autovacuum2-1.10 {
+  CREATE TABLE t2(x);
+  PRAGMA freelist_count;
+} {0}
+
+# Rig the autovacuum-pages callback to always return zero.  No
+# autovacuum will happen.
+#
+proc autovac_page_callback_off {schema filesize freesize pagesize} {
+  return 0
+}
+sqlite3_autovacuum_pages db autovac_page_callback_off
+do_execsql_test autovacuum2-1.20 {
+  BEGIN;
+  INSERT INTO t1(x) VALUES(zeroblob(10000));
+  DELETE FROM t1;
+  PRAGMA freelist_count;
+  COMMIT;
+  PRAGMA freelist_count;
+} {9 9}
+
+finish_test