Add the SQLITE_FCNTL_SIZE_HINT operator to sqlite3_file_control() and use it

to give the VFS hints about the ultimate size of a database file when the
file is growing.

FossilOrigin-Name: 2b7e3b4a30d6a7c4a8a4b8e7dd2ed728b565c96d

manifest

@@ -1,8 +1,8 @@
 -----BEGIN PGP SIGNED MESSAGE-----
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-C Fix\sa\sbug\sin\sthe\snew\scheckpoint\scomputation.\s\sAlso\supdate\sthe\scheckpoint\nalgorithm\sin\sthe\stest\sscripts\sto\salign\swith\sthe\snew\simplementation.
+C Add\sthe\sSQLITE_FCNTL_SIZE_HINT\soperator\sto\ssqlite3_file_control()\sand\suse\sit\nto\sgive\sthe\sVFS\shints\sabout\sthe\sultimate\ssize\sof\sa\sdatabase\sfile\swhen\sthe\nfile\sis\sgrowing.
-D 2010-05-19T19:09:38
+D 2010-05-19T19:26:06
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in a5cad1f8f3e021356bfcc6c77dc16f6f1952bbc3
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -155,9 +155,9 @@ F src/os.c b994b2f4c9a2c406a20d43b59c22ed39a1e704d1
 F src/os.h 207c26793c9b518aa670480a3a262250dd3c98b1
 F src/os_common.h a8f95b81eca8a1ab8593d23e94f8a35f35d4078f
 F src/os_os2.c 665876d5eec7585226b0a1cf5e18098de2b2da19
-F src/os_unix.c 6db3289dcfe8f2ec0277ad025e072254252a00c9
+F src/os_unix.c 6db01eb2c87856f9c9ea40d497941c54ae1b27ff
 F src/os_win.c 70c4a3327716213b59adf3a8adf2d5318b044a19
-F src/pager.c 1e163a82ae8405433dca559831caa06aafbba3b0
+F src/pager.c d3284a6bbedeaa4ef3f5668af309d4381df97618
 F src/pager.h 76466c3a5af56943537f68b1f16567101a0cd1d0
 F src/parse.y ace5c7a125d9f2a410e431ee3209034105045f7e
 F src/pcache.c ace8f6a5ecd4711cc66a1b23053be7109bd437cf
@@ -171,7 +171,7 @@ F src/resolve.c ac5f1a713cd1ae77f08b83cc69581e11bf5ae6f9
 F src/rowset.c 69afa95a97c524ba6faf3805e717b5b7ae85a697
 F src/select.c c03d8a0565febcde8c6a12c5d77d065fddae889b
 F src/shell.c fd4ccdb37c3b68de0623eb938a649e0990710714
-F src/sqlite.h.in aa9086ea3a365843d62ce120cba458ecad6edd63
+F src/sqlite.h.in ef766c813d377a0f3f5e6131d0a2667ecd6301c1
 F src/sqlite3ext.h 69dfb8116af51b84a029cddb3b35062354270c89
 F src/sqliteInt.h c1ca9bed7c963343f90edaf0ec31b8ff4b43fb01
 F src/sqliteLimit.h 196e2f83c3b444c4548fc1874f52f84fdbda40f3
@@ -816,14 +816,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
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+R 18ea315c422c82833ce8122e2306d4ce
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manifest.uuid

@@ -1 +1 @@
-8b6056f2ee596f31b157a792fac05d11f7cb63bb
+2b7e3b4a30d6a7c4a8a4b8e7dd2ed728b565c96d

src/os_unix.c

@@ -3045,6 +3045,12 @@ static int unixFileControl(sqlite3_file *id, int op, void *pArg){
       *(int*)pArg = ((unixFile*)id)->lastErrno;
       return SQLITE_OK;
     }
+    case SQLITE_FCNTL_SIZE_HINT: {
+      sqlite3_int64 szFile = *(sqlite3_int64*)pArg;
+      unixFile *pFile = (unixFile*)id;
+      ftruncate(pFile->h, szFile);
+      return SQLITE_OK;
+    }
 #ifndef NDEBUG
     /* The pager calls this method to signal that it has done
     ** a rollback and that the database is therefore unchanged and

src/pager.c

@@ -3332,6 +3332,14 @@ static int pager_write_pagelist(PgHdr *pList){
     rc = pagerOpentemp(pPager, pPager->fd, pPager->vfsFlags);
   }
 
+  /* Before the first write, give the VFS a hint of what the final
+  ** file size will be.
+  */
+  if( pPager->dbSize > (pPager->dbOrigSize+1) && isOpen(pPager->fd) ){
+    sqlite3_int64 szFile = pPager->pageSize * (sqlite3_int64)pPager->dbSize;
+    sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_SIZE_HINT, &szFile);
+  }
+
   while( rc==SQLITE_OK && pList ){
     Pgno pgno = pList->pgno;
 

src/sqlite.h.in

@@ -678,11 +678,19 @@ struct sqlite3_io_methods {
 ** into an integer that the pArg argument points to. This capability
 ** is used during testing and only needs to be supported when SQLITE_TEST
 ** is defined.
+**
+** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
+** layer a hint of how large the database file will grow to be during the
+** current transaction.  This hint is not guaranteed to be accurate but it
+** is often close.  The underlying VFS might choose to preallocate database
+** file space based on this hint in order to help writes to the database
+** file run faster.
 */
 #define SQLITE_FCNTL_LOCKSTATE        1
 #define SQLITE_GET_LOCKPROXYFILE      2
 #define SQLITE_SET_LOCKPROXYFILE      3
 #define SQLITE_LAST_ERRNO             4
+#define SQLITE_FCNTL_SIZE_HINT        5
 
 /*
 ** CAPI3REF: Mutex Handle